which ip address assignment method leads to fewer efforts for information technology professionals

Understanding IP Address Assignment: A Complete Guide

Introduction

In today's interconnected world, where almost every aspect of our lives relies on the internet, understanding IP address assignment is crucial for ensuring online security and efficient network management. An IP address serves as a unique identifier for devices connected to a network, allowing them to communicate with each other and access the vast resources available on the internet. Whether you're a technical professional, a network administrator, or simply an internet user, having a solid grasp of how IP addresses are assigned within the same network can greatly enhance your ability to troubleshoot connectivity issues and protect your data.

The Basics of IP Addresses

Before delving into the intricacies of IP address assignment in the same network, it's important to have a basic understanding of what an IP address is. In simple terms, an IP address is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. It consists of four sets of numbers separated by periods (e.g., 192.168.0.1) and can be either IPv4 or IPv6 format.

IP Address Allocation Methods

There are several methods used for allocating IP addresses within a network. One commonly used method is Dynamic Host Configuration Protocol (DHCP). DHCP allows devices to obtain an IP address automatically from a central server, simplifying the process of managing large networks. Another method is static IP address assignment, where an administrator manually assigns specific addresses to devices within the network. This method provides more control but requires careful planning and documentation.

Considerations for Efficient IP Address Allocation

Efficient allocation of IP addresses is essential for optimizing network performance and avoiding conflicts. When assigning IP addresses, administrators need to consider factors such as subnetting, addressing schemes, and future scalability requirements. By carefully planning the allocation process and implementing best practices such as using private IP ranges and avoiding overlapping subnets, administrators can ensure smooth operation of their networks without running out of available addresses.

IP Address Assignment in the Same Network

When two routers are connected within the same network, they need to obtain unique IP addresses to communicate effectively. This can be achieved through various methods, such as using different subnets or configuring one router as a DHCP server and the other as a client. Understanding how IP address assignment works in this scenario is crucial for maintaining proper network functionality and avoiding conflicts.

Basics of IP Addresses

IP addresses are a fundamental aspect of computer networking that allows devices to communicate with each other over the internet. An IP address, short for Internet Protocol address, is a unique numerical label assigned to each device connected to a network. It serves as an identifier for both the source and destination of data packets transmitted across the network.

The structure of an IP address consists of four sets of numbers separated by periods (e.g., 192.168.0.1). Each set can range from 0 to 255, resulting in a total of approximately 4.3 billion possible unique combinations for IPv4 addresses. However, with the increasing number of devices connected to the internet, IPv6 addresses were introduced to provide a significantly larger pool of available addresses.

IPv4 addresses are still predominantly used today and are divided into different classes based on their range and purpose. Class A addresses have the first octet reserved for network identification, allowing for a large number of hosts within each network. Class B addresses reserve the first two octets for network identification and provide a balance between network size and number of hosts per network. Class C addresses allocate the first three octets for network identification and are commonly used in small networks.

With the depletion of available IPv4 addresses, IPv6 was developed to overcome this limitation by utilizing 128-bit addressing scheme, providing an enormous pool of potential IP addresses - approximately 3.4 x 10^38 unique combinations.

IPv6 addresses are represented in hexadecimal format separated by colons (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334). The longer length allows for more efficient routing and eliminates the need for Network Address Translation (NAT) due to its vast address space.

Understanding these basics is essential when it comes to assigning IP addresses in a network. Network administrators must consider various factors such as the number of devices, network topology, and security requirements when deciding on the IP address allocation method.

In the next section, we will explore different methods of IP address assignment, including Dynamic Host Configuration Protocol (DHCP) and static IP address assignment. These methods play a crucial role in efficiently managing IP addresses within a network and ensuring seamless communication between devices.

Methods of IP Address Assignment

IP address assignment is a crucial aspect of network management and plays a vital role in ensuring seamless connectivity and efficient data transfer. There are primarily two methods of assigning IP addresses in a network: dynamic IP address assignment using the Dynamic Host Configuration Protocol (DHCP) and static IP address assignment.

Dynamic IP Address Assignment using DHCP

Dynamic IP address assignment is the most commonly used method in modern networks. It involves the use of DHCP servers, which dynamically allocate IP addresses to devices on the network. When a device connects to the network, it sends a DHCP request to the DHCP server, which responds by assigning an available IP address from its pool.

One of the key benefits of dynamic IP address assignment is its simplicity and scalability. With dynamic allocation, network administrators don't have to manually configure each device's IP address. Instead, they can rely on the DHCP server to handle this task automatically. This significantly reduces administrative overhead and makes it easier to manage large networks with numerous devices.

Another advantage of dynamic allocation is that it allows for efficient utilization of available IP addresses. Since addresses are assigned on-demand, there is no wastage of unused addresses. This is particularly beneficial in scenarios where devices frequently connect and disconnect from the network, such as in public Wi-Fi hotspots or corporate environments with a high turnover rate.

However, dynamic allocation does have some drawbacks as well. One potential issue is that devices may receive different IP addresses each time they connect to the network. While this might not be an issue for most users, it can cause problems for certain applications or services that rely on consistent addressing.

Additionally, dynamic allocation introduces a dependency on the DHCP server. If the server goes down or becomes unreachable, devices will not be able to obtain an IP address and will be unable to connect to the network. To mitigate this risk, redundant DHCP servers can be deployed for high availability.

Static IP Address Assignment

Static IP address assignment involves manually configuring each device's IP address within the network. Unlike dynamic allocation, where addresses are assigned on-demand, static assignment requires administrators to assign a specific IP address to each device.

One of the main advantages of static IP address assignment is stability. Since devices have fixed addresses, there is no risk of them receiving different addresses each time they connect to the network. This can be beneficial for applications or services that require consistent addressing, such as servers hosting websites or databases.

Static assignment also provides greater control over network resources. Administrators can allocate specific IP addresses to devices based on their requirements or security considerations. For example, critical servers or network infrastructure devices can be assigned static addresses to ensure their availability and ease of management.

However, static IP address assignment has its limitations as well. It can be time-consuming and error-prone, especially in large networks with numerous devices. Any changes to the network topology or addition/removal of devices may require manual reconfiguration of IP addresses, which can be a tedious task.

Furthermore, static allocation can lead to inefficient utilization of available IP addresses. Each device is assigned a fixed address regardless of whether it is actively using the network or not. This can result in wastage of unused addresses and may pose challenges in scenarios where addressing space is limited.

In order to efficiently allocate IP addresses within a network, there are several important considerations that need to be taken into account. By carefully planning and managing the allocation process, network administrators can optimize their IP address usage and ensure smooth operation of their network.

One of the key factors to consider when assigning IP addresses is the size of the network. The number of devices that will be connected to the network determines the range of IP addresses that will be required. It is essential to accurately estimate the number of devices that will need an IP address in order to avoid running out of available addresses or wasting them unnecessarily.

Another consideration is the type of devices that will be connected to the network. Different devices have different requirements in terms of IP address assignment. For example, servers and other critical infrastructure typically require static IP addresses for stability and ease of access. On the other hand, client devices such as laptops and smartphones can often use dynamic IP addresses assigned by a DHCP server.

The physical layout of the network is also an important factor to consider. In larger networks with multiple subnets or VLANs, it may be necessary to segment IP address ranges accordingly. This allows for better organization and management of IP addresses, making it easier to troubleshoot issues and implement security measures.

Security is another crucial consideration when allocating IP addresses. Network administrators should implement measures such as firewalls and intrusion detection systems to protect against unauthorized access or malicious activities. Additionally, assigning unique IP addresses to each device enables better tracking and monitoring, facilitating quick identification and response in case of any security incidents.

Efficient utilization of IP address ranges can also be achieved through proper documentation and record-keeping. Maintaining an up-to-date inventory of all assigned IP addresses helps prevent conflicts or duplicate assignments. It also aids in identifying unused or underutilized portions of the address space, allowing for more efficient allocation in the future.

Furthermore, considering future growth and scalability is essential when allocating IP addresses. Network administrators should plan for potential expansion and allocate IP address ranges accordingly. This foresight ensures that there will be sufficient addresses available to accommodate new devices or additional network segments without disrupting the existing infrastructure.

In any network, the assignment of IP addresses is a crucial aspect that allows devices to communicate with each other effectively. When it comes to IP address assignment in the same network, there are specific considerations and methods to ensure efficient allocation. In this section, we will delve into how two routers in the same network obtain IP addresses and discuss subnetting and IP address range distribution.

To understand how two routers in the same network obtain IP addresses, it's essential to grasp the concept of subnetting. Subnetting involves dividing a larger network into smaller subnetworks or subnets. Each subnet has its own unique range of IP addresses that can be assigned to devices within that particular subnet. This division helps manage and organize large networks efficiently.

When it comes to assigning IP addresses within a subnet, there are various methods available. One common method is manual or static IP address assignment. In this approach, network administrators manually assign a specific IP address to each device within the network. Static IP addresses are typically used for devices that require consistent connectivity and need to be easily identifiable on the network.

Another widely used method for IP address assignment is Dynamic Host Configuration Protocol (DHCP). DHCP is a networking protocol that enables automatic allocation of IP addresses within a network. With DHCP, a server is responsible for assigning IP addresses dynamically as devices connect to the network. This dynamic allocation ensures efficient utilization of available IP addresses by temporarily assigning them to connected devices when needed.

When considering efficient allocation of IP addresses in the same network, several factors come into play. One important consideration is proper planning and design of subnets based on anticipated device count and future growth projections. By carefully analyzing these factors, administrators can allocate appropriate ranges of IP addresses for each subnet, minimizing wastage and ensuring scalability.

Additionally, implementing proper security measures is crucial when assigning IP addresses in the same network. Network administrators should consider implementing firewalls, access control lists (ACLs), and other security mechanisms to protect against unauthorized access and potential IP address conflicts.

Furthermore, monitoring and managing IP address usage is essential for efficient allocation. Regular audits can help identify any unused or underutilized IP addresses that can be reclaimed and allocated to devices as needed. This proactive approach ensures that IP addresses are utilized optimally within the network.

The proper assignment of IP addresses is crucial for maintaining network security and efficiency. Throughout this guide, we have covered the basics of IP addresses, explored different methods of IP address assignment, and discussed considerations for efficient allocation.

In conclusion, understanding IP address assignment in the same network is essential for network administrators and technical professionals. By following proper allocation methods such as DHCP or static IP assignment, organizations can ensure that each device on their network has a unique identifier. This not only enables effective communication and data transfer but also enhances network security by preventing unauthorized access.

Moreover, considering factors like subnetting, scalability, and future growth can help optimize IP address allocation within a network. Network administrators should carefully plan and allocate IP addresses to avoid conflicts or wastage of resources.

Overall, a well-managed IP address assignment process is vital for the smooth functioning of any network. It allows devices to connect seamlessly while ensuring security measures are in place. By adhering to best practices and staying updated with advancements in networking technology, organizations can effectively manage their IP address assignments.

In conclusion, this guide has provided a comprehensive overview of IP address assignment in the same network. We hope it has equipped you with the knowledge needed to make informed decisions regarding your network's IP address allocation. Remember that proper IP address assignment is not only important for connectivity but also plays a significant role in maintaining online security and optimizing network performance.

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How are ip addresses managed and distributed.

IP addresses are managed by the Internet Assigned Numbers Authority (IANA), which has overall responsibility for the Internet Protocol (IP) address pool, and by the Regional Internet Registries (RIRs) to which IANA distributes large blocks of addresses.

The RIRs manage, distribute, and publicly register IP addresses and related Internet number resources, such as Autonomous System Numbers (ASN) and reverse Domain Name System (DNS ) delegations within their respective regions. They do this according to policies which are developed within their respective regional communities, through open and bottom-up processes.

There are currently five RIRs:

AfriNIC – African region
APNIC – Asia Pacific region
ARIN – North America and several Caribbean and North Atlantic islands
LACNIC – Latin America and the Caribbean
RIPE NCC – Europe, the Middle East, and parts of Central Asia

The five RIRs together also form the Number Resource Organization (NRO), which carries out joint activities of the RIRs, including joint technical projects, liaison activities, and policy co-ordination. For more background on IP address management visit:

IANA’s Overview of IP Address Services
Development of the Regional Internet Registry System , an article published in Cisco’s Internet Protocol Journal

How are IPv6 addresses allocated?

Both IPv4 and IPv6 addresses are allocated to those who show that they need addresses for their networks.

Shouldn’t addresses be allocated on a geographical basis to ensure that distribution is equitable?

For technical reasons the allocation of IP addresses has to follow the topology of the network and not geography or national borders.

Therefore, the addresses are allocated for use in specific networks, as they are required. RIRs allocate IP addresses using community-developed policies that are designed to ensure that distribution is fair and equitable.

In the early days of the Internet, the method for distributing IP addresses was less formal, resulting in some organisations receiving disproportionately large address ranges.

The RIRs were formed to provide a better way of distributing addresses. They have been successful at developing fair and equitable distribution policies. They have also helped to provide stability of the address pool and routing tables throughout a long period of rapid growth.

What happens when IPv4 addresses run out?

The Internet, in its current form, already has. According to the Number Resource Organization, the world officially ran out of IPv4 addresses in February 2011 .

The only option now is to divide the allocated properties into smaller portions or to start trading what’s already been assigned – both moves could complicate and compromise your privacy.

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What would happen if you told someone that you lived at 34 Elm Street, and when that person turned onto your road found four different houses with the number “34” on them? They'd probably find your place eventually but wouldn't be too pleased. Neither would you or your mail carrier. J And all of you folks are much smarter than computers. Where I am going with this is that like street addresses, IP addresses must be unique for them to be useful.

Since IP datagrams are sent only within the confines of the IP internetwork, they must be unique within each internetwork. If you are a company with your own private internetwork, this isn't really a big problem. Whoever is in charge of maintaining the internetwork keeps a list of what numbers have been used where and makes sure that no two devices are given the same address. However, what happens in a public network with many different organizations? Here, it is essential that the IP address space be managed across the organizations to ensure that they use different addresses. It's not feasible to have each organization coordinate its activities with each other one. Therefore, some sort of centralized management authority is required.

At the same time that we need someone to ensure that there are no conflicts in address assignment, we don't want every user of the network to have to go to this central authority every time they need to make a change to their network. It makes more sense to have the authority assign numbers in blocks or chunks to organizations based on the number of devices they want to connect to the network. The organizations can manage those blocks as they see fit, and the authority's job is made easier because it deals in blocks instead of billions of individual addresses and machines.

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How are IP addresses actually assigned?

I'm having a hard time understanding how a governing body assigns IP addresses, companies use BGP to advertise those IPs, and how the internet works. Then, where the hell does DNS come in?

Can anyone suggest a good read of how this stuff actually works? I suppose I have several questions. The first is, does ARIN (or any other governing body) actually matter? If they weren't around, would there be chaos? When they assign a block, they don't LITERALLY assign it? You have to use BGP to advertise, correct? I have always been used to a closed hosting environment (dedicated/shared) where you have routed IPs.

Then, how does DNS come in to play? With my registrar I am able to register a DNS server (eNom) - what does that actually mean? I've installed Bind and made all of that work, and I run my own DNS servers, but who are they registering that DNS server with? I just don't get it.

I feel like this is something I should know and I don't, and I'm getting really frustrated. It's like.. simple.. how does the internet work? From assigning IPs, to companies routing them, and DNS.

I guess I have an example - I have this IP space let's say 158.124.0.0/16 (example). The company has 158.124.0.0/17 internet facing. (First of all, why do companies get blocks of IPs assigned and then not use them? Why don't they use use reserved internal space 10.x and 192.x?). So, that's where I'm at. What would I do to actually get these IPs on the Internet and available? Let's say I have a data center in Chicago and one in New York. I'm not able to upload a picture, but I can link one here: http://begolli.com/wp-content/gallery/tech/internetworkings.png

I'm just trying to understand how from when the IP block is assigned, to a company using BGP (attaining a public AS #?), and then how DNS comes in to play?

What would something look like from my picture? I've tried to put together a scenario, not sure if I did a good job.

domain-name-system

6 As a professional system administrator, or someone working in a related field, we are expected to know these things. For any bits that may be a little unclear vast numbers of books and Internet articles have already been published. This is also not the kind of question, or set of questions, that can be properly addressed by a Q&A site like SF. – John Gardeniers Commented May 31, 2011 at 22:48
2 I don't really have a problem with this question - I look at it the same way as the "Subnetting 101" question & answer: It's something every sysadmin should know, but some may have slipped through without the requisite knowledge. We can't cover it as exhaustively as subnetting, but I think having it as a quick-and-dirty primer is a Good Thing. – voretaq7 Commented Jun 1, 2011 at 15:50
1 @John - I think there are many different levels. Like I stated, I grew up learning in a static environment as far as networks went. I never really dealt with ISPs, border routers, and configuring blocks of IPs. I have had the pleasure of having many dedicated servers, configuring linux distributions, securing them, running web applications, and being able to manage those boxes. There are different sides to the spectrum, and I don't think we are expected to know these things. We are expected to know specialized tasks. Some people know networking engineering real well.. others do not. – Vegim Commented Jun 2, 2011 at 16:08

4 Answers 4

Leased ip blocks.

IPs are assigned in blocks by IANA to the Regional Internet Registries (RIR). See this ( list and map ) of the RIRs. The RIRs then lease out smaller blocks IPs to individual companies (usually ISPs). There are requirements (including fees and proof of use) for getting a distribution and failing to maintain these means a loss of lease.

Once a company has leased one or more blocks from the RIR, they need some way of telling the rest of the world where to find a particular IP (or set thereof: subnets). This is where BGP comes into play. BGP uses a large network concept called an Autonomous System (AS). The AS knows how to route within itself. When routing to another network it only knows about AS Gateways and where the "next hop" toward those external addresses. AS numbers are managed by IANA as well.

Within an AS, even one as large as an ISP, they might use several routing protocols (RIP, OSPF, BGP, EIGRP, and ISIS come to mind) to route traffic internally. It's also possible to use Static Routing Tables, but entirely impractical in most applications. Internal routing protocols are a huge topic, so I'll simplify by saying there are other questions on Server Fault that can do those topics more justice than I can here.

Humans don't remember numbers well, so we invented host names. Skipping the history, we use the Domain Naming System (DNS) to keep track of what hostname points to what IP address. There is a central registry for these, also managed by IANA, and they determine what Top Level Domains (TLD) (eg ".com" or ".net") go in the Root Zone, which is served by the Root Servers. IANA delegates administration of the "root zone", this administrator only accepts updates from qualified Registrars.

You can use a Registrar to "purchase" a domain name, which is a subdomain of a TLD. This registration essentially creates that subdomain and assigns you control over it's Name Server (NS) and Glue (A) records. You point these to a DNS server that hosts your domain . When a client wants to resolve your IP from a domain name, the client contacts their DNS server which does a recursive lookup, starting with the root server, finding your DNS server and eventually getting the relevant information.

Everyone Agrees

As for the "governing bodies": everyone just agrees to use them. There are no (or very few) laws requiring anyone to cooperate at all. The Internet works because people choose to cooperate . The governing bodies provide a means of easy cooperation. All the various RFCs, "Standards", and such - nobody is being forced to use them. But we understand that society is built on cooperation, and it's in our own self interests to do so.

The efficiency bred by cooperation is the same reason BGP is popular, everyone basically agrees to use it. In the days of ArpaNet they started with hand configured route tables; then gradually progressed to a more comprehensive system as the Internet grew in complexity, but everyone just "agreed" to use whatever new standard. Similarly name resolution stated with host files that networks would distribute, and eventually grew into the DNS system we know today. ("Agreed" in quotes because many times a minority set a requirement for a new standard and nobody else had a better alternative, so it was accepted).

This level of cooperation requires trusting IANA, a lot. As you've seen they manage most of the various systems' cores. IANA is currently a US Government sponsored Non-Profit corporation (similar to the US Post Office), it is not part of the government, though only barely removed. In past years there was concern that the US Goernment might exercise some control over IANA as a "weapon" against other world governments or civilians (particularly through laws like SOPA and PIPA, which were not passed, but may be the basis for future laws).

Currently IANA has taken it upon themselves to raise funding (despite being a non-profit company) through the creation of new TLDs. The "xxx" TLD was viewed by some as an extortionist-style fundraising campaign, as a large percentage of registrants were "defending" their name. IANA has also taken applications for privately owned TLDs (at $180,000 each; they have suspended the application process after being inundated with applications, nearly half being from Amazon alone. Many of these applications resulted in new gTLDs .

No problem! Good answer - this will be good to have to point to for people needing the overview. – Shane Madden Commented Jun 1, 2011 at 1:05
Do you think you could elaborate on the delegations for reverse DNS? This is a great answer that touches on the related subjects already, so adding that info would close the loop on the whole thing. – Andrew B Commented Feb 28, 2015 at 20:59

All advertisements to the public internet, the DFZ (Default-Free Zone), is done via BGP (Border Gateway Protocol), how ISP's do internal routing varies a lot. Most would use BGP internally as well both between their own routers (BGP is often used in conjunction with an IGP such as OSPF) and also with clients, if you don't have your own AS number you can use a private AS to peer with your ISP and when they announce your address space to the DFZ they simply remove the private AS from the as-path. For smaller non-redundant links you can use static routing as well on the PE. The actual "assignment" is just in the database of your registrar, the whois database, RIPE/ARIN etc run their own databases for this purpose.

Try running the command whois 158.124.0.0/16 on a Linux box.

Same goes with DNS, the reverse DNS server is specified in whois records.

This is a very old question, but I had many of the same questions in figuring out how the Internet works . Like the other answers, the networking books give an overview of BGP and DNS but still left me confused. For example, a.root-servers.net through m.root-servers.net are given as the root servers, but how does a DNS service know where to find those servers if they can't use DNS themselves.

The basics of IP, subnetting, DNS, etc. are assumed to be known by this answer. I am addressing "gaps" I, and probably the questioner, have on how the Internet works. By no means am I an expert, but this is my understanding of the gaps.

IP Addresses

The first thing to note is that when the Internet started out as ARPANET, everybody knew everybody and routing tables for IP addresses were handcoded. I assume the assignment process for IP's was done over the phone. As the Internet became too big, BGP was used by multiple networks (AS's) to advertise they had public IP's or could get to a public IP through their AS to another AS. The trust was there that an AS wouldn't advertise an IP they didn't have.

Today, there's not as much trust. Instead, ISP's can download and authenticate the IP allocations to each AS from IANA and the regional authorities. These downloads are now authenticated through public key cryptography. So when IANA "assigns an IP address," they are changing their record (or really the regional authority changes their record). All other AS's can download and authenticate their records.

These records are important because ISP's can't take the word of other ISP's that they have the IP addresses. The ISP's can compare the BGP advertisement with the authenticated IP records. If any BGP advertisement shows the last AS as an AS other than what's in IANA's and RIR's authenticated record, the BGP advertisement does not change their own routing.

More commonly, a rogue ISP or AS can advertise they have a route through their AS they don't have. AS1 has an IP registered and AS5 currently uses AS5 -> AS4 -> AS3 -> AS1 -> IP. AS2 advertises to AS5 a route of AS5 -> AS2 -> AS1 -> IP. Except AS2 doesn't actually have a connection with AS1. It can just lose the packets, maybe to frustrate AS1's hosting customers. Or AS2 could be a small company network with a multihomed arrangement with AS5 and AS1. Their router is misconfigured and advertises a path through a small company network. Nearly all ISP's throw away such advertisements of their BGP customers and only pass on terminating BGP advertisements.

More likely, you have the case of Pakistan trying to shut off Youtube in Pakistan through such IP hijacking, and shutting off Youtube outside of Pakistan too since AS's outside of Pakistan assumed their BGP advertisements were correct.

In the end, there isn't a perfect defense against such IP hijacking. In most countries like the US, such abuse of BGP can be punished as breach of contract and other ISP's will shut off peering connections with that AS if they have to. An ISP could also disregard the whole IANA and RIR apparatus and redirect the IP addresses to their own servers. That won't work for any https sites though, assuming the ISP doesn't have the private keys for any CA's. There is very little to gain from it economically. It only happens with authoritarian governments, such as Egypt recently shutting off all BGP advertisements to their ISP's from outside the country.

DNS Servers

DNS is somewhat simpler once the IP tables are correct. The root servers are all hardcorded IP addresses in the DNS server code. a.root-servers.net is 198.41.0.4 and the IP address is anycast within one AS. In the case of a.root-servers.net, the AS is Verisign and there are five different sites. In the US, the two sites are New York and LA. Anycasting is like if you had an address of 123 Main Street and you said "It doesn't matter what town you are in, go to 123 Main Street and you'll find one of my businesses." Both 123 Main Street in NY and LA will give the same answer for all top-level domains. The AS, in this case Verisign, figures out internally which server has the fewest hops through OSPF, internal BGP, and other routing protocols. So a router in Denver may go to LA while a router in Chicago goes to New York. The same routing process can be used for Anycast hosts because the hosts don't offer to route traffic.

One of the root servers gives which IP address for the com top-level domain. Then that domain gives the domain for yoursite.com. The registrars really have a contract with whoever runs the top-level domain. So if the top-level domain currently doesn't have a record for yoursite.com, it has access to add a record with their who-is server. Then, with the access the registrar gave you to yoursite.com's DNS records, you change the records in their DNS server to go to your IP address.

Because DNS all depends on multiple IP addresses going to the right place, you have the same issue as before with AS's authenticating the IP registry and then the BGP assignments. That is the key piece for an http website. Https has the added protection of certificates. So, an ISP can't reroute requests for their own root servers and top-level domain servers to give their own IP for, say, citibank.com. If they did, the IP address given to the user will be a different IP address, but their server won't have Citibank's private key.

and no, I'm not kidding(I got started with this book 15 years ago, but it's still very relevant): http://www.amazon.com/Internet-Dummies-John-R-Levine/dp/0764506749

Then, come back here with the BGP questions =)

2 It looks like the first part of your answer go chopped off somehow. – John Gardeniers Commented Jun 1, 2011 at 1:34

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Address Assignment Practices in IPv4 and IPv6

which ip address assignment method leads to fewer efforts for information technology professionals

Stephen Strowes

Stephen is a principal engineer in the Office of the CTO at Fastly, where he spends his time trying to figure out what the Internet is. He obtained his PhD in Internet routing scalability from the University of Glasgow in 2012. More

11 min read

In prior work, we've studied IPv4 allocation patterns in domestic ISPs. Time has passed, and IPv6 adoption has continued, so in this article we review our current observations on IPv4 and IPv6 assignment practices.

ISPs assign parts of their address space to users and subscribers. These assignments are typically not static. Often in a domestic network, a subscriber's CPE will negotiate a lease on an individual IPv4 address or an IPv6 subnet via a DHCP or RADIUS exchange.

How long do these assignments last for? In IPv4 it's common for users to receive an individual address, but in IPv6 entire subnets are delegated. How large are those subnets? There are BCP recommendations that steer networks towards particular subnet sizes, but networks are free to select subnet sizes according to their own addressing plans. Can we observe the size of the subnets that are assigned from measurement data?

The duration and size of assignments has various implications:

Reputation : If you're a content or service provider who occasionally has to block abusive behaviour from the network, what is the potential collateral damage?
Geolocation : If you generate geo datapacks, how reliable do your customers consider them? If you rely on geo datapacks, how stale might they be?
Measurement : If you're a network researcher attempting to scan active portions of the IPv6 address space, how much of an ISP's space is in use and how is it subdivided?

Ongoing Measurements

RIPE Atlas runs, among other built-in measurements , echo measurements. These are HTTP requests from probes to servers operated by the RIPE NCC, the response to which contains the IP address observed by the server. These measurements therefore report the publicly visible address from any probe, whether it's a globally visible IPv6 address or the shared address on an IPv4 CGNAT. The measurements run every 15 minutes, giving us a dataset of IPv4 and IPv6 address changes over many years. Given we know which probe performs each echo request, we have data on when each probe's IPv4 and IPv6 addresses change, and whether or not those changes are synchronous.

The RIPE Atlas platform has extensive coverage in some networks, but not all networks. In addition to the RIPE Atlas dataset, we make use of data from a large CDN. This dataset contains address associations purposefully constructed from browser sessions where a resource has been requested over both IPv4 and an IPv6. The IPv4 addresses are masked to /24s and the IPv6 addresses are masked to /64s. This dataset gives us a bound on when two addresses appear to have been assigned to the same user. Utilising five months of data, we have over 30 billion address associations in this dataset, allowing us to cover more networks than with the RIPE Atlas dataset alone.

We make use of this larger dataset in the full paper (linked at the bottom of this article). In this article, we'll look more closely at the RIPE Atlas dataset and related data in the RIPE database.

Address Lifetimes

The long-term scarcity of IPv4 addresses and intermittent connectivity (e.g., dial-up connections) led networks towards leasing IPv4 addresses from shared pools. Leases expire, and networks differ on how sticky addresses are or how long a lease should last. IPv6 deployments have taken place in a different era, where many more connections are likely to be always-on, and the scarcity argument is removed.

In Figure 1, we show the difference between address assignment lifetimes in IPv4 and IPv6.

Figure 1: Frequency of assignment durations in IPv4 and IPv6 environments. Strong vertical lines indicate Y% of time is spent with the durations on the X axis.

To understand the above plots, consider Deutsche Telekom (DTAG). On the left, we show IPv4-only probes, and on the right IPv6 (largely dual-stacked) probes. The vertical lines indicate common address durations; IPv4-only hosts appear to spend just under 60% of their time with 1 day assignments (or shorter), while the IPv6 durations are typically longer than 1 day (over 60% of their assignments persist longer than 1 day). In the paper, we additionally show that IPv4 lifetimes for dual-stacked hosts tend to have longer lifetimes than for single-stacked IPv4 networks, if not quite as long as IPv6 prefix delegations.

We see a clear divergence between how long IPv4 and IPv6 assignments persist in these networks. Indeed, we observe that IPv6 assignments tend to persist longer in most networks. This distinction between IPv4 and IPv6 may be important to consider when determining how long to block abusive behaviour or how stale to consider geo data, for example.

Delegated Prefixes

ISPs delegate an IPv6 prefix to each subscriber, but the size of that delegated prefix is decided by the ISP. A natural lower limit on the size of the delegated prefix is /64, though best practice suggests that larger subnets should be defined . ISPs are not consistent in how they delegate prefixes, nor do they have any need to be! Some ISPs describe their address architecture for subscribers publicly, and some do not. What can we glean instead from measurement data?

We take a simple approach to identifying the size of the prefixes assigned to a network: count the zero bits prior to the /64 boundary. The notion of prefix delegation entitles CPE or network operators to subdivide their network as they see fit, but the intuition is that many networks choose to keep things simple and their CPE uses the zeroth /64 in the delegated prefix. Taking this simple approach, we are able to identify patterns per-network in Figure 2, based on those runs of zeroes in the addresses.

Figure 2: Inferred delegated prefix lengths from RIPE Atlas data. Y% of probes in a given network appear to have a delegated prefix of length X. The value in parenthesis on the right is the number of probes in the dataset for that ISP.

Across these networks, where we have many probes and many address changes to inspect, we observe some distinct signals:

Many, but not all, networks appear to be assigning /56s to customers
Comcast, which typically appears to assign a /64
Kabel, which typically assigns a /62
Free, which typically assigns a /60
Deutsche Telekom has two spikes, at /56 and /64, and this appears to be driven by a distinction whereby a /56 is issued and some CPE models cycle through multiple /64s in that space .
Netcologne, which typically assigns a /48.

So using this data alone, we can already observe that there's a wide variation in how much address space each ISP is willing to give their customers.

Assignment Size Data in the RIPE Database

It is useful for anybody outside of a network to know the size of the prefixes assigned to customers. Some operators publish their addressing practices on the web, but one additional means to share information -- which we don't touch on in the paper -- is via the RIPE database (a.k.a., whois).

An LIR -- in our case, domestic ISPs -- with IPv6 space can subdivide that space and ultimately assign parts of it to end users. LIRs are obligated to describe their IPv6 assignments in the database . An overview of how to document IPv6 assignments in the RIPE database is available here . In short, inet6num objects may describe a specific assignment to a customer, or may describe a pool of space from which assignments are made to customers.

The latter category of objects have the status AGGREGATED-BY-LIR , and inet6num objects with this status must include an assignment-size parameter. This parameter states the block size that end users should be uniformly assigned from within the address space described by the object.

There are 44 thousand inet6num objects with an assignment-size attribute. The values registered typically align with what you may expect: the most common listed assignment-size is /56 (in over 81% of the inet6num objects), then /64 (11%), then /48 (6%). The remaining values are fewer than 2% of the registered assignment-sizes, including 244 /128s; it'd be interesting to know how people are using network prefixes longer than /64!

The data in the database may be reliable as a means to verify our measurements above. In order to align these two datasets, in Figure 3 we've taken the same set of probes and the /64s that were observed from those probes as we used for Figure 2. But instead of inferring the delegated prefix from the bits we saw active, we search the RIPE database for the covering inet6num object, and look for an assignment-size value in that object.

The results look as follows:

Figure 3: Registered assignment-size values in the RIPE Database for the prefixes assigned to probes. Percentage of probes refers to percentage when assignment-size information exists.

Note that some networks aren't registering this field (or they exist out of the RIPE region), so for those networks we have nothing to compare. We have data for Deutsche Telekom, Liberty Global, Kabel DE, Free, Netcologne, BT, and Sky.

We have a few observations to make in the above:

There's a clear intent across these networks to select /56s for delegation to subscribers, which is good. That both fits with BCOP-690 and with the patterns measured in Figure 2.
Deutsche Telekom clearly issues a /56, according to the database. This is a clear distinction to the split in Figure 2 between the identified /56s and /64s, typically a distinction in CPE behaviour. Our heuristic was deliberately simple, and with a little more work we should be able to detect cycling within a common subnet.
Netcologne (AS8422) provides a /48 to all probes that we have address change data for in Figure 2, and indeed the database agrees in Figure 3. A full 16-bits of address space for their customers!
Liberty Global (LGI) has operations across many countries and for LGI prefixes with matching assignment-size data, we see a split between /36s and /64s. The /36 value comes from Cablecom in Switzerland , though in Figure 2 we observed nothing close to a /36 and so that feels like bad or stale data in the database. The /64 value comes from T-Mobile Austria , and so likely represents assignments to mobile subscribers. Figure 2 reveals probes that appear to have been assigned a /56, so we presumably are simply identifying parts of LGI that aren't lodging this data in the database.

We'd love to be able to get more of the networks we've studied specifying this information publicly, and the RIPE database seems a trustworthy means to enable this. The partial data we have above seems like it'd be useful for the applications outlined at the start of this article.

Implications

Understanding domestic stability of the IP address space -- be it temporal or spatial -- is useful for various applications. The key here is that assumptions from the IPv4 world may not carry to the IPv6 world.

But this might not be such a bad thing. For example, if a service is typically willing to drop traffic from a single IPv4 address for 24 hours to dampen some malicious behaviour, that same heuristic applied to IPv6 is likely to be too short rather than too long. That's a reasonable position as an operator: the collateral damage is lessened.

Similarly, a block on a single /64 is likely to be too narrow: a knowledgable attacker could select a subnet elsewhere within their /56, and then you may have a game of whack-a-mole on your hands. But since a /64 is an atomic unit of IPv6 networks, it's also likely not to block more than one household in the first attempt.

More per-network knowledge is useful for everybody, and it's likely to be in the community's best interests if networks publicise more about their addressing plans.

There's much more detail in the full paper which we presented at CoNEXT 2020 , so go check it out! We have additional graphs available on this web page . And if you prefer video form, the short (12.5 minute) video for our paper is here:

More from this author

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Methods of Assigning IP Addresses

This section discusses methods of assigning IP addresses to end systems and explains their influence on administrative overhead. Address assignment includes assigning an IP address, a default gateway, one or more domain name servers that resolve names to IP addresses, time servers, and so forth. Before selecting the desired IP address assignment method, the following questions should be answered:

■ How many devices need an IP address?

■ Which devices require static IP address assignment?

■ Is IP address renumbering expected in the future?

■ Is the administrator required to track devices and their IP addresses?

■ Do additional parameters (default gateway, name server, and so forth) have to be configured?

■ Are there any availability issues?

■ Are there any security issues?

Static Versus Dynamic IP Address Assignment Methods

Following are the two basic IP address assignment strategies:

■ Static: An IP address is statically assigned to a system. The network administrator configures the IP address, default gateway, and name servers manually by entering them into a special file or files on the end system with either a graphical or text interface. Static address assignment is an extra burden for the administrator—especially on large-scale networks— who must configure the address on every end system in the network.

■ Dynamic: IP addresses are dynamically assigned to the end systems. Dynamic address assignment relieves the administrator of manually assigning an address to every network device. Instead, the administrator must set up a server to assign the addresses. On that server, the administrator defines the address pools and additional parameters that should be sent to the host (default gateway, name servers, time servers, and so forth). On the host, the administrator enables the host to acquire the address dynamically; this is often the default. When IP address reconfiguration is needed, the administrator reconfigures the server, which then performs the host-renumbering task. Examples of available address assignment protocols include Reverse Address Resolution Protocol, Boot Protocol, and DHCP. DHCP is the newest and provides the most features.

When to Use Static or Dynamic Address Assignment

To select either a static or dynamic end system IP address assignment method or a combination of

the two, consider the following:

■ Node type: Network devices such as routers and switches typically have static addresses. End-user devices such as PCs typically have dynamic addresses.

■ The number of end systems: If there are more than 30 end systems, dynamic address assignment is preferred. Static assignment can be used for smaller networks.

■ Renumbering: If renumbering is likely to happen and there are many end systems, dynamic address assignment is the best choice. With DHCP, only DHCP server reconfiguration is needed; with static assignment, all hosts must be reconfigured.

■ Address tracking: If the network policy requires address tracking, the static address assignment method might be easier to implement than the dynamic address assignment method. However, address tracking is also possible with dynamic address assignment with additional DHCP server configuration.

■ Additional parameters: DHCP is the easiest solution when additional parameters must be configured. The parameters have to be entered only on the DHCP server, which then sends the address and those parameters to the clients.

■ High availability: Statically assigned IP addresses are always available. Dynamically assigned IP addresses must be acquired from the server; if the server fails, the addresses cannot be acquired. To ensure reliability, a redundant DHCP server is required.

■ Security: With dynamic IP address assignment, anyone who connects to the network can acquire a valid IP address, in most cases. This might be a security risk. Static IP address assignment poses only a minor security risk.

The use of one address assignment method does not exclude the use of another in a different part of the network.

Guidelines for Assigning IP Addresses in the Enterprise Network

The typical enterprise network uses both static and dynamic address assignment methods. As shown in Figure 6-14, the static IP address assignment method is typically used for campus network infrastructure devices, in the Server Farm and Enterprise Data Center modules, and in the modules of the Enterprise Edge (the E-Commerce, Internet Connectivity, Remote Access and VPN, and WAN and MAN and Site-to-Site VPN modules). Static addresses are required for systems such as servers or network devices, in which the IP address must be known at all times for connectivity, general access, or management.

Figure 6-14 IP Address Assignment in an Enterprise Network

Enterprise Campus

Server Farm

Enterprise Edge

Building Access & £	I
Building Distribution 3
Campus Core
X

E-Commerce f* 1

Database,

Application,

Web Servers

Internet Connectivity ' .....* 1

Static Servers

Enterprise Branch
S3

Continue reading here: Name Resolution

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Readers' Questions

How do know that your network is configured to assign an ip address to the thermostat?

To determine if your network is configured to assign an IP address to the thermostat, you can follow these steps: Check if your thermostat is connected to Wi-Fi: Ensure that your thermostat is successfully connected to your home Wi-Fi network. Most thermostats have an indicator light or display that shows the Wi-Fi connectivity status. Access your router's settings: Open a web browser on a device connected to the same network as your thermostat and enter your router's IP address (e.g., 192.168.1.1) in the address bar. Consult your router's user manual or contact your internet service provider for assistance if you don't know the router's IP address. Log in to your router's admin interface: Enter your router's admin username and password to log in to the router's settings page. If you haven't changed the login credentials, you may find the default ones on the router or in its manual. Locate the DHCP settings: DHCP (Dynamic Host Configuration Protocol) is responsible for assigning IP addresses to devices on your network. Find the DHCP settings page in your router's admin interface. It might be under a section like "LAN settings," "Network settings," "DHCP settings," or similar. Verify DHCP is enabled: Ensure that DHCP is enabled or turned on in your router's settings. This setting allows your router to assign IP addresses dynamically. Typically, DHCP is enabled by default. Check the assigned IP address table: Look for a section or tab in your router's settings that displays the list of devices connected to your network along with their assigned IP addresses. The table may be labeled as "Connected Devices," "Device list," "DHCP Client List," or alike. Ensure your thermostat appears in the list and has been assigned an IP address. If your thermostat appears in the assigned IP address table, it means your network is configured to assign an IP address to it. If it doesn't, you may need to troubleshoot the thermostat's Wi-Fi connection or contact the manufacturer's support for further assistance.

What protocol automatically configures ip configuration for a client?

The protocol that automatically configures IP configuration for a client is called DHCP (Dynamic Host Configuration Protocol). It allows clients to obtain IP addresses, subnet masks, default gateways, and other network configuration parameters automatically from a DHCP server. This eliminates the need for manual configuration of IP addresses on each client device.

Which protocol can configure a computer's ip address and subnet mask automatically?

The Dynamic Host Configuration Protocol (DHCP) is designed to automatically configure a computer's IP address and subnet mask. By using DHCP, a computer can obtain network configuration information including IP address, subnet mask, default gateway, and DNS server(s) without manual intervention.

When using fixed allocation dhcp, what is used to determine a computer's ip?

When using fixed allocation DHCP (Dynamic Host Configuration Protocol), the computer's Media Access Control (MAC) address is used to determine its IP (Internet Protocol) address. The DHCP server maintains a mapping between MAC addresses and IP addresses, known as a DHCP reservation. When a computer with a specific MAC address requests an IP address from the DHCP server, it checks if a reservation exists for that MAC address. If a reservation is found, the DHCP server assigns the corresponding IP address to the computer.

Which type of server dynamically assigns an ip address to a host?

A dynamic host configuration protocol (DHCP) server is responsible for assigning dynamic IP addresses to hosts on a network.

Which allocation method can be used with a dynamic host configuration?

The Dynamic Host Configuration Protocol (DHCP) typically uses the "Dynamic Allocation" method for allocating IP addresses to client devices. In this method, a pool of IP addresses is created, and the DHCP server selects an available address from that pool and assigns it to the requesting device. The address is leased to the device for a specific period, known as the lease duration. Once the lease expires, the address can be released back to the pool and assigned to another device. This allows for efficient and flexible allocation of IP addresses in dynamic network environments.

Which address should be configured as the default gateway address of a client device?

The default gateway address for a client device should be the IP address of the router or gateway that connects the client device to the network. This router or gateway is responsible for forwarding network traffic between the client device and other networks or the internet.

How to statically assign an ip address?

To statically assign an IP address, follow these steps: On your device, go to the network settings. This can usually be found in the control panel or system preferences. Look for the network adapter or connection that you want to configure and select it. Go to the properties or settings of the network adapter. Look for an option such as "Internet Protocol Version 4 (TCP/IPv4)" and select it. Click on the "Properties" button or double-click on the selected option. In the properties window, select the option to "Use the following IP address". Enter the desired IP address, subnet mask, default gateway, and DNS server addresses. Contact your network administrator or Internet Service Provider (ISP) for the appropriate values if you're unsure. Click on "OK" or "Apply" to save the changes. Please note that the steps to assign a static IP address may vary slightly depending on the operating system and device you are using.

Why is dhcp for ipv4 preferred for use on large networks?

There are several reasons why DHCP (Dynamic Host Configuration Protocol) for IPv4 is preferred for use on large networks: Efficient IP address management: Large networks typically have a large number of devices that need unique IP addresses. DHCP allows for automated IP address allocation, ensuring that each device connected to the network receives a unique IP address without manual configuration. This eliminates the need for manual IP address management, making it easier to handle IP address assignments on a large scale. Centralized control: DHCP allows for centralized management and control over IP address allocation. Network administrators can configure DHCP servers to provide specific IP address ranges, subnet masks, default gateways, and other network settings. This centralized control simplifies the network administration process and ensures consistency across the network. Scalability: DHCP is highly scalable, allowing for the dynamic allocation and re-allocation of IP addresses as devices join or leave the network. As new devices connect to the network, DHCP servers can quickly assign them IP addresses from the available pool. Similarly, when devices disconnect or are powered off, their IP addresses can be released back to the pool for subsequent allocation. Reduced configuration errors: Manual configuration of IP addresses on a large network can be error-prone, leading to network connectivity issues or IP address conflicts. With DHCP, the chances of configuration errors are minimized as the IP addresses are assigned automatically. This improves network reliability and reduces troubleshooting efforts. Network flexibility: Large networks often require network reconfiguration or changes, such as adding new subnets or modifying IP address ranges. DHCP simplifies these network changes by allowing administrators to modify the DHCP server configuration, rather than manually updating settings on each individual device. Overall, DHCP for IPv4 offers a more efficient, scalable, and reliable method of IP address allocation and management on large networks, thereby reducing administrative overhead and providing greater control over network resources.

How to assign ip address to a clents?

To assign an IP address to a client, you will need to follow these steps: Access your router's settings: In order to assign an IP address to a client, you need to be connected to the network router or have administrative access to its settings. Determine the client's MAC address: The Media Access Control (MAC) address is a unique identifier assigned to a network interface card (NIC) of a client. You can usually find the MAC address on the client's network settings or by using command prompts such as "ipconfig /all" (Windows) or "ifconfig" (Linux/Mac). Reserve an IP address in the router's settings: Access your router's settings interface (generally through a web browser by entering the router's IP address). Look for a section such as "DHCP Reservation" or "Address Reservation" and select it. Locate the option to add a new reservation and enter the client's MAC address along with the IP address you want to assign to it. Save and apply the changes: Once you have entered the necessary information, save the changes and apply them. This will ensure that the router reserves the assigned IP address for the client in the future. Restart the client device: To ensure the client receives the new assigned IP address, it is recommended to restart the client device. This will trigger it to request an IP address from the router, and if the reservation was successful, it will be assigned the specific IP address you specified. Note: The specific process may vary slightly depending on the router model and firmware version. Consult your router's manual or manufacturer's website for detailed instructions if needed.

What methods are used to assign tcp/ip parameters to network hosts (select two.)?

Dynamic Host Configuration Protocol (DHCP): DHCP is a network management protocol that automatically assigns IP addresses and other TCP/IP parameters to network hosts. It allows hosts to obtain necessary network configuration settings from a DHCP server dynamically. Manual Configuration: In this method, the TCP/IP parameters are manually assigned to network hosts by network administrators. This involves manually configuring the IP address, subnet mask, default gateway, and other parameters in the network host's settings. It requires manual input and configuration on each host individually.

Which network address and subnet mask does apipa use (select two.)?

-Network Address: 169.254.0.0 -Subnet Mask: 255.255.0.0

Which part of the network assigns an ip address?

The Dynamic Host Configuration Protocol (DHCP) assigns IP addresses to devices on a network.

Which organization is responsible for allocating public ip addresses?

The Internet Assigned Numbers Authority (IANA) is responsible for allocating public IP addresses. It is an organization that works under the supervision of the Internet Corporation for Assigned Names and Numbers (ICANN). IANA administers the global Internet Protocol address space and other Internet Protocol-related symbols and numbers.

Is responsible for the internet's domain name system and the allocation of ip addresses?

The Internet Corporation for Assigned Names and Numbers (ICANN) is responsible for the internet's domain name system and the allocation of IP addresses.

What is the name of the organization responsible for assigning public ip addresses?

The organization responsible for assigning public IP addresses is the Internet Assigned Numbers Authority (IANA).

How to change static ip address?

1. Open the Control Panel. 2. Go to Network and Internet > Network and Sharing Center. 3. Click the Change Adapter Settings link on the left-hand side. 4. Right-click on the active network adapter and select Properties. 5. Select the Internet Protocol Version 4 (TCP/IPv4) option and click the Properties button. 6. Select the Use the following IP address option and enter the static IP address, subnet mask, and default gateway. 7. Click Okay to save the settings.

What protocol is responsible for assigning ip addresses to hosts on most networks?

The Dynamic Host Configuration Protocol (DHCP) is responsible for assigning IP addresses to hosts on most networks.

Which protocol assigns ip address to the client connected in the internet?

The Dynamic Host Configuration Protocol (DHCP) is responsible for assigning IP addresses to clients who are connected to the Internet.

What are the types of ip address assignment?

Static IP address: This type of IP address assignment is a permanent address assigned to a device by an administrator. Dynamic IP address: This type of IP address assignment is a temporary address assigned to a device by a DHCP server. Private IP address: This type of IP address is used for internal networks and is typically assigned for the use of devices within a local network. Public IP address: This type of IP address is used for public networks and is assigned by an internet service provider (ISP).

Which protocol provides a way to automate the ip configuration?

Dynamic Host Configuration Protocol (DHCP) is a network protocol that enables a server to automatically assign an IP address to a computer from a defined range of numbers configured for a given network.

Which protocol assigns ip address to the client?

Dynamic Host Configuration Protocol (DHCP) is the protocol used to assign IP addresses to client devices.

Which two automatic addressing assignments are supported by dhcpv4 (choose two.)?

Dynamic Host Configuration Protocol (DHCP) Automatic Private IP Addressing (APIPA)

Which protocol should you use if you want to dynamically assign ip addresses to network clients?

The Dynamic Host Configuration Protocol (DHCP) should be used if you want to dynamically assign IP addresses to network clients.

What protocol is used to assign computers on a lan dynamic ip addresses?

Dynamic Host Configuration Protocol (DHCP)

How to manually assign ip address?

Open the Control Panel. Click on Network and Sharing Center. Choose Change adapter settings. Right click on the connection whose IP address you want to assign manually and select Properties. Select Internet Protocol Version 4 (TCP/IPv4). Click on the Properties button. Select the option "Use the following IP address". Enter the appropriate IP address and Subnet mask values. Enter the Default Gateway Address. Enter the Preferred and Alternate DNS server addresses. Click OK and then close out of all other open windows. Test your new settings.

How to assign ip address to devices?

Connect the device to the network. Use a DHCP server to assign an IP address to the device. Configure the device with a static IP address. Connect the device to a router and set the router to assign IP addresses to the device. Configure the device manually with a static IP address.

How to assign ip adress?

Open the Control Panel. Select "Network and Internet". Select "Network and Sharing Center". Select "Change adapter settings". Right-click on the network connection you want to change the IP address for and select "Properties". Select "Internet Protocol Version 4 (TCP/IPv4)". Select "Properties". Select "Use the following IP address". Enter the desired IP address. Enter the subnet mask. Enter the default gateway. Select "OK" to save the settings and close the window.

Why is dhcp preferred for use on large networks?

DHCP is preferred for use on large networks because it helps to automate the network configuration process. It eliminates the need for manual configuration of network settings. DHCP also helps reduce the risk of errors, by assigning the same IP address each time a computer connects to the network. It ensures that each client has its own unique IP address, allowing devices to communicate with each other. This increases the performance and reliability of the network.

Which two types of devices are typically assigned static ip addresses (choose two.)?

Servers Network Printers

How do you assign a server with an IP address?

To assign an IP address to a server, you will need to access the server's network settings in its operating system or hardware. From there, you can assign a static IP address or a dynamic one using DHCP.

What are the ways of assigning the Ip address?

There are several ways to assign an IP address to a device. Here are some common methods: Dynamic Host Configuration Protocol (DHCP): DHCP is commonly used in modern networks, where a central server automatically assigns IP addresses to devices on the network. The DHCP server manages a pool of available IP addresses and leases them to devices on request. Manual Configuration: This involves manually assigning a static IP address to a device. It is typically used for devices that require a consistent IP address, such as servers or network printers. The administrator manually enters the desired IP address, along with other network settings, directly into the device's network configuration. Zero-configuration Networking (Zeroconf): Zeroconf, also known as Automatic Private IP Addressing (APIPA), allows devices on a network to automatically assign IP addresses to themselves without a central server. It is commonly used in small home or office networks where there is no DHCP server available. Link-Local Addressing: Link-local addresses are IP addresses that are automatically assigned to devices on a local network segment without the need for a DHCP server. These addresses are typically used for network troubleshooting or communication within a small local network. Static IP Reservation: In some cases, network administrators may choose to use DHCP but reserve specific IP addresses for certain devices. This ensures that these devices always receive the same IP address each time they connect to the network. Dynamic DNS (DDNS): DDNS allows devices with dynamic IP addresses (addresses that change periodically) to be accessed by a hostname instead of the IP address. It involves using a service that updates the DNS records whenever the device's IP address changes. The method used to assign IP addresses depends on the network setup, device requirements, and network administrator's preferences.

Which method is used to assign ip address?

Dynamic Host Configuration Protocol (DHCP) is a network protocol used to assign IP addresses to devices on a network.

How to allocate ip address for network design?

Determine the IP address range to be allocated: Determine the total number of IP addresses needed and then calculate the appropriate IP address range based on the number of devices that need to be connected. Design the subnet mask: Design a subnet mask to divide the IP address range into subnets. Allocate the IP addresses: Allocate IP addresses to each device on the network based on their individual subnet masks. Configure the network devices: Configure the network devices with their assigned IP addresses and the appropriate subnet mask. Test the network: Test the network to ensure that all devices are assigned the correct IP addresses and the network is functioning properly.

How are IP adresses assigned to nodes in a network?

IP addresses are assigned to nodes in a network through DHCP (Dynamic Host Configuration Protocol). A DHCP server assigns a unique IP address to each node in a network from a pool of available IP addresses. The node then requests a lease from the DHCP server and stores the address for the duration of the lease.

When should a network administrator assign static IP addresses to network devices?

A network administrator should assign static IP addresses to network devices when the devices need to be accessed remotely and securely, or when the device needs to host services such as a web server, FTP server, or database. Static IP addresses are also useful for assigning devices to VLANs, managing traffic flow to and from the device, and configuring quality of service (QoS).

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■ How many devices need an IP address?

■ Which devices require static IP address assignment?

■ Is IP address renumbering expected in the future?

■ Is the administrator required to track devices and their IP addresses?

■ Do additional parameters (default gateway, name server, and so forth) have to be configured?

■ Are there any availability issues?

■ Are there any security issues?

Static Versus Dynamic IP Address Assignment Methods

Following are the two basic IP address assignment strategies:

When IP address reconfiguration is needed, the administrator reconfigures the server, which then performs the host-renumbering task. Examples of available address assignment protocols include Reverse Address Resolution Protocol, Boot Protocol, and DHCP. DHCP is the newest and provides the most features.

When to Use Static or Dynamic Address Assignment

To select either a static or dynamic end system IP address assignment method or a combination of the two, consider the following:

■ Node type: Network devices such as routers and switches typically have static addresses. End-user devices such as PCs typically have dynamic addresses.

■ The number of end systems: If there are more than 30 end systems, dynamic address assignment is preferred. Static assignment can be used for smaller networks.

The typical enterprise network uses both static and dynamic address assignment methods. As shown in Figure, the static IP address assignment method is typically used for campus network infrastructure devices, in the Server Farm and Enterprise Data Center modules, and in the modules of the Enterprise Edge (the E-Commerce, Internet Connectivity, Remote Access and VPN, and WAN and MAN and Site-to-Site VPN modules). Static addresses are required for systems such as servers or network devices, in which the IP address must be known at all times for connectivity, general access, or management.

Using DHCP to Assign IP Addresses

DHCP is used to provide dynamic IP address allocation to hosts. DHCP uses a client/server model; the DHCP server can be a Windows server, a UNIX-based server, or a Cisco IOS device. Cisco IOS devices can also be DHCP relay agents and DHCP clients. Figure 5.8 shows the steps that occur when a DHCP client requests an IP address from a DHCP server.

Step 1 The host sends a DHCPDISCOVER broadcast message to locate a DHCP server.

Step 2 A DHCP server offers configuration parameters such as an IP address, a MAC address, a domain name, a default gateway, and a lease for the IP address to the client in a DHCPOFFER unicast message.

Step 3 The client returns a formal request for the offered IP address to the DHCP server in a DHCPREQUEST broadcast message.

Step 4 The DHCP server confirms that the IP address has been allocated to the client by returning a DHCPACK unicast message to the client.

A DHCP client might receive offers from multiple DHCP servers and can accept any one of the offers; the client usually accepts the first offer it receives. An offer from the DHCP server is not a guarantee that the IP address will be allocated to the client; however, the server usually reserves the address until the client has had a chance to formally accept the address. DHCP supports three possible address allocation mechanisms:

■ Manual: The network administrator assigns an IP address to a specific MAC address. DHCP is used to dispatch the assigned address to the host.

■ Automatic: DHCP permanently assigns the IP address to a host.

■ Dynamic: DHCP assigns the IP address to a host for a limited time (called a lease) or until the host explicitly releases the address. This mechanism supports automatic address reuse when the host to which the address has been assigned no longer needs the address.

Name Resolution

Names are used to identify different hosts and resources on the network and to provide userfriendly interaction with computers; a name is much easier to remember than an IP address. This section covers the purpose of name resolution, provides information about different available name resolution strategies, and discusses Domain Name System (DNS) name resolution. Hosts (computers, servers, printers, and so forth) identify themselves to each other using various naming schemes. Each computer on the network can have an assigned name to provide easier communication between devices and among users. Because the IP network layer protocol uses IP addresses to transport datagrams, a name that is used to identify a host must be mapped or resolved into an IP address; this is known as name resolution. To select the desired name resolution method, the following questions should be answered:

■ How many hosts require name resolution?

■ Are applications that depend on name resolution present?

■ Is the network isolated, or is it connected to the Internet?

■ If the network is isolated, how frequently are new hosts added, and how frequently do names change?

Static Versus Dynamic Name Resolution

The process of resolving a hostname to an IP address can be either static or dynamic. Following are the differences between these two methods:

■ Static: With static name-to-IP-address resolution, both the administrative overhead and the configuration are very similar to those of a static address assignment strategy. The network administrator manually defines name-to-IP-address resolutions by entering the name and IP address pairs into the local database (HOSTS file) using either a graphical or text interface. Manual entries create additional work for the administrator; they must be entered on every host and are prone to errors and omissions.

■ Dynamic: The dynamic name-to-IP-address resolution is similar to the dynamic address assignment strategy. The administrator has to enter the name-to-IP-address resolutions only on a local DNS server rather than on every host. The DNS server then performs the name-to- IP-address resolution. Renumbering and renaming are easier with the dynamic name-to-IPaddress resolution method.

When to Use Static or Dynamic Name Resolution

The selection of either a static or dynamic end-system name resolution method depends on the following criteria:

■ The number of hosts: If there are more than 30 end systems, dynamic name resolution is preferred. Static name resolution is manageable for fewer hosts.

■ Isolated network: If the network is isolated (it does not have any connections to the Internet) and the number of hosts is small, static name resolution might be appropriate. The dynamic method is also possible; the choice is an administrative decision.

■ Internet connectivity: When Internet connectivity is available for end users, static name resolution is not an option, and dynamic name resolution using DNS is mandatory.

■ Frequent changes and adding of names: When dealing with frequent changes and adding names to a network, dynamic name resolution is recommended.

■ Applications depending on name resolution: If applications that depend on name resolution are used, dynamic name resolution is recommended.

Using DNS for Name Resolution

To resolve symbolic names to actual network addresses, applications use resolver or name resolver programs, which are usually part of the host operating system. An application sends a query to a name resolver that resolves the request with either the local database (HOSTS file) or the DNS server. To enable DNS name resolution, the network administrator sets up the DNS server, enters information about hostnames and corresponding IP addresses, and configures the hosts to use the DNS server for name resolution.

DHCP and DNS Server Location in a Network

As illustrated in Figure below, DHCP and DNS servers can be located at multiple places in the network, depending on the service they support.

For the Enterprise Campus, DHCP and internal DNS servers should be located in the Server Farm; these servers should be redundant. For remote locations, Cisco routers can provide DHCP and DNS at the Enterprise Edge. External DNS servers should be redundant—for example, at two service provider facilities, or one at a service provider facility and one in a demilitarized zone at the Enterprise Campus or remote data center.

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