ip block assignments

ARIN Lookup

About arin lookup.

This test will query the American Registry for Internet Numbers (ARIN) database and tell you who an IP address is registered to. Generally speaking, you will input an IP address and find out what ISP or hosting provider uses that block for its customers. Very large end customers may have there own ARIN allocations. Normally, this is used for finding abuse contacts to report bad behavior.

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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 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 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 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 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 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 Jun 1, 2011 at 1:34

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IANA IPv4 Special-Purpose Address Registry

Registry included below

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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• 4. IPv6 ADDRESS ALLOCATION AND ASSIGNMENT POLICIES

Important notes:

The PDF document hosted on this page is the authoritative version of the Policy Manual. The web version is provided to make it easier for readers to quickly browse the different sections of the Manual.

In the event of a conflict between the web version and the pdf version of the Manual, the pdf version shall control.

This document and/or information was originally written in Spanish, the official language of Uruguay, the country where LACNIC is legally incorporated and whose laws and regulations LACNIC must meet. Likewise, unofficial information and/or documents are also written in Spanish, as this is the language in which most of LACNIC's collaborators and officers work and communicate. We do our best to ensure that our translations are reliable and serve as a guide for our non-Spanish-speaking members. However, discrepancies may exist between the translations and the original document and/or information written in Spanish. In this case, the original text written in Spanish will always prevail.

This chapter describes policies for the allocation and assignment of the globally-unique IPv6 address space.

[RFC2373, RFC2373bis] designate 2000::/3 to be the global unicast address space that IANA may allocate to RIRs. This chapter concerns initial and subsequent allocations of the 2000::/3 unicast address space, for which RIRs formulate allocation and assignment policies. Because end sites will generally be given /48 assignments [RFC 6177], the particular emphasis of this document is on recommendations to LIRs/ISPs regarding their assignments to connected users and customers.

4.2.Definitions

The following terms are specific to IPv6 allocation policies.

4.2.1.Utilization

Unlike IPv4, IPv6 is generally assigned to end sites in fixed amounts.

The actual utilization of addresses within each assignment will be quite low when compared to IPv4 assignments.

In IPv6, "utilization" is only measured in terms of the number of prefixes assigned to end users, not their size or the number of addresses actually used in those prefixes. This is how it should be understood throughout this document.

4.2.2.HD-Ratio

HD-Ratio is a way of measuring the efficiency of address assignment [RFC 3194]. It is an adaptation of the HD-Ratio originally defined in [RFC1715] and is expressed as follows:

         Log (number of assigned objects)

HD = -------------------------------------------------------------

         Log (maximum number of assignable objects)

where, in the case of this document, the objects are IPv6 site addresses (/48s) assigned from an IPv6 prefix of a given size (see Appendix 2).

4.3.IPv6 Policy Principles

To address the goals described in the previous section, the policies in this chapter discuss and follow the basic principles described below.

4.3.1.Address space not to be considered property

It is contrary to the goals of this document and is not in the interests of the Internet community as a whole for address space to be considered freehold property.

The policies in this chapter are based upon the understanding that globally-unique IPv6 unicast address space is licensed for use rather than owned. Specifically, IP addresses will be allocated and assigned on a license basis, with licenses subject to renewal on a periodic basis. The granting of a license is subject to specific conditions applied at the start or renewal of the license.

RIRs will generally renew licenses automatically, provided requesting organizations are making a good-faith effort at meeting the criteria under which they qualified for or were granted an allocation or assignment. However, in those cases where a requesting organization is not using the address space as intended, or is showing bad faith in following through on the associated obligation, RIRs reserve the right to not renew the license.

Note that when a license is renewed, the new license will be evaluated under and governed by the applicable IPv6 address policies in place at the time of renewal, which may differ from the policy in place at the time of the original allocation or assignment.

4.3.2.Minimum allocation

RIRs will apply a minimum size for IPv6 allocations, to facilitate prefix-based filtering.

The minimum allocation size for IPv6 address space is /32.

4.3.3.Consideration of IPv4 infrastructure

Where an existing IPv4 service provider requests IPv6 space for eventual transition of existing services to IPv6, the number of present IPv4 customers may be used to justify a larger request than would be justified if based solely on the IPv6 infrastructure.

4.4.Policies for Allocations and Assignments

4.4.1.initial allocation, 4.4.1.1.ipv6 allocation to a lir or isp with a previous ipv4 allocation from lacnic.

LACNIC will allocate IPv6 address blocks to a LIR or ISP that has already received an IPv4 allocation from LACNIC. If the allocation would be announced in the Internet inter-domain routing system, the organization must announce the allocated block with the minimum possible level of disaggregation to the one that is publishing the IP blocks. LACNIC will allocate a single /32 when received a request from a LIR or ISP with a previous IPv4 allocation. In case that the organization request the allocation of an address block larger than a /32, the LIR or ISP must present the documentation required in section 4.4.1.3.

4.4.1.2.IPv6 allocation to a LIR or ISP without a previous IPv4 allocation from LACNIC.

To qualify for an initial allocation of IPv6 address space, an organization must:

• Be an LIR or ISP.
• Document a detailed plan for the services and IPv6 connectivity to be offered

to other organizations (clients) or self-owned/related departments/entities/sites to which it will assign /48s.

• Announce the allocated block in the Internet inter-domain routing system, with the minimum possible level of disaggregation to the one that is publishing the IP blocks, within a period no longer than 12 months.
• Offer IPv6 services to clients or self-owned/related entities (including departments and/or sites) physically located in the region covered by LACNIC within a period not longer than 24 months.

4.4.1.3.Initial Allocation Size

Organizations may qualify for an initial allocation larger than a /32 by submitting documentation that justifies the request.

In this case, the initial allocation shall be based on the space needed to serve the organization's clients, number of users, extent of its infrastructure, hierarchical and/or geographic structure, infrastructure segmentation for security or other reasons, and the longevity anticipated for the initial allocation.

In order to comply with the requirements mentioned above, the prefix assigned to the ISP must be within the binary "boundaries" of the IP address.

4.4.1.4.Rectifying the size of initial allocations

During IPv6 deployment, if an organization finds that the size of the initial allocation it requested no longer satisfies its needs, the organization may submit a new addressing plan to LACNIC, without having to wait until it can fulfill the requirements for a subsequent allocation, and therefore the organization will not have to prove utilization thresholds, but, instead the desire to apply a different addressing plan that is better suited to the reality of the deployment.

The new size will be adjusted according to the new addressing plan as specified in section 4.4.1.3., and will thus qualify for extending the current prefix the necessary number of bits.

If it were not possible to provide this prefix length because the adjacent space is already being used by another organization, or if making the allocation would not leave sufficient space for subsequent allocations, LACNIC shall inform the applicant, who may choose to:

• a) receive a new prefix with the new requested size and renumber their network and return "original" initial allocation to LACNIC within 6 months, or
• b) receive a complementary prefix to complete their addressing plan, and announce both the "original" initial prefix and the new prefix resulting from the new allocation. For all effects and purposes, in the case of subsequent allocations, both allocations shall be considered as if they were a single allocation. Each organization may only use this procedure once, so for this "second opportunity" they should carefully study the final medium and long term network addressing plan.

4.4.2.Subsequent Allocation

Organizations that hold an existing IPv6 allocation may receive a subsequent allocation in accordance with the following policies.

4.4.2.1.Subsequent Allocation Criteria

Subsequent allocation will be provided when an organization (ISP/LIR) satisfies the evaluation threshold of past address utilization in terms of the number of sites in units of /48 assignments. The HD-Ratio [RFC 3194] is used to determine the utilization thresholds that justify the allocation of additional address as described below.

4.4.2.2.Applied HD-Ratio

The HD-Ratio value of 0.94 is adopted as indicating an acceptable address utilization for justifying the allocation of additional address space. Appendix 2 provides a table showing the number of assignments that are necessary to achieve an acceptable utilization value for a given address block size.

4.4.2.3.Subsequent Allocation Size

When an organization has achieved an acceptable utilization for its allocated address space, it is immediately eligible to obtain an additional allocation that results in a doubling of the address space allocated to it. Where possible, the allocation will be made from an adjacent address block, meaning that its existing allocation is extended by one bit to the left.

If an organization requires more address space, the organization shall provide documentation justifying the space it needs to serve its clients, number of users, extent of its infrastructure, hierarchical and/or geographic structure, infrastructure segmentation for security or other reasons, and the longevity anticipated for the initial allocation.

4.4.2.4.LIR-to-ISP Allocation

There is no specific policy for an organization (LIR) to allocate address space to subordinate ISPs. Each LIR organization may develop its own policy for subordinate ISPs to encourage optimum utilization of the total address block allocated to the LIR. However, all /48 assignments to End Users sites are required to be registered either by the LIR or its subordinate ISPs in such a way that the RIR/NIR can properly evaluate the HD-Ratio when a subsequent allocation becomes necessary.

4.4.3. Assignments by ISPs

LIRs must make IPv6 assignments in accordance with the following provisions.

4.4.3.1.Assignment address space size

 Assignment of address space. Assignments are to be made in accordance with the need specified by the ISP's user as well as with existing recommendations [RIPE-690, https://www.ripe.net/publications/docs/ripe-690], highlights of which are summarized below:

* End sites or users must be assigned a prefix that is a multiple of "n" /64’s which must be enough to meet their current and planned needs, considering existing protocols and future possibilities and thus avoiding possible renumbering scenarios.

* The size of the prefix to be assigned is an operational decision of the LIR/ISP, although the selection of /48s is recommended for simpler and more functional infrastructure for all the endpoints of the network.

* Persistent prefix assignments are recommended to avoid undesired failures.

* Using a /64 prefix for point-to-point with GUAs is recommended.

The size of LIRs/ISPs assignments does not concern RIRs/NIRs.

Accordingly, RIRs/NIRs will not request detailed information on IPv6 user networks as they did in IPv4, except for the cases described in Section 4.4.2 and for the purpose of measuring utilization as defined in this chapter.

4.4.3.2.Assignment to Operator’s Infrastructure

An organization (ISP/LIR) may assign a /48 per PoP as the service infrastructure of an IPv6 service operator. Each assignment to a PoP is regarded as one assignment regardless of the number of users using the PoP. A separate assignment can be obtained for the in-house operations of the operator.

4.4.4.Direct Assignments to End Sites

LACNIC will assign portable (provider-independent) IPv6 addresses directly to end sites in accordance with the two policies detailed in Sections 4.4.4.1 and 4.4.4.2, depending on whether or not the organization holds portable IPv4 addresses previously assigned by LACNIC.

4.4.4.1.Direct assignment of portable IPv6 addresses to End Sites having portable IPv4 addresses previously assigned by LACNIC

LACNIC will assign portable IPv6 address blocks directly to end sites if they hold portable IPv4 addresses previously assigned by LACNIC.

• In case of announcing the assignment on the Internet inter-domain routing system, the receiving organization shall announce the block maintaining de-aggregation to a minimum in accordance with the announcing organization's needs.

Assignments will be made in blocks always greater than or equal to a /48.

Subsequent assignments must be duly documented and justified. Where possible, such assignments will be made from a contiguous address block (i.e., extending the existing assignment "n" bits to the left).

4.4.4.2.Direct assignment of portable IPv6 addresses to End sites not having portable IPv4 addresses previously assigned by LACNIC

LACNIC will assign portable IPv6 address blocks directly to end sites that satisfy the following requirements:

• Not be an LIR or ISP.
• Provide detailed information showing how the requested block will be used within the following three, six and twelve months.
• Submit addressing plans for at least a year.

4.4.4.3. Rectifying the size of an initial assignment

An End User organization may submit a new addressing plan to LACNIC if the plan initially submitted and used to justify the initial assignment no longer satisfies their current needs. This applies on a one-time basis.

The new prefix will be consistent with the new plan and shall comply with Sections 4.4.4.1 or 4.4.4.2.

If it were not possible to provide a prefix of that size, either because the adjacent prefixes are already being used by other organizations or because such an assignment would leave insufficient space for subsequent assignments, LACNIC shall inform this to the requesting organization, which will have the following options:

- receiving a new block with the requested prefix that fully covers the need justified by the user in the new plan, with the commitment to renumber its network and return the original block to LACNIC within a period of 6 months;

- receiving a new block which, together with the block that has already been assigned, covers the need justified by the user in the new plan, and maintaining both blocks.

Each organization may use this procedure only once.

4.4.5.IPv6 Micro-Assignments

LACNIC shall make micro-assignments in case of projects and network infrastructure that are key or critical for the operation and development of IPv6 within the region, such as, among others, IXPs (Internet Exchange Points), NAPs (Network Access Points), RIRs, DNS ccTLD providers. These assignments shall be made in prefixes longer than or equal to /32 but always shorter than or equal to /48.

In the case of IXPs or NAPs, in order to be eligible for this type of assignment, the organization must meet the following requirements

• Prove by means of their bylaws their IXP or NAP capacity. The organization shall have at least three members and an open policy for the association of new members
• Submit a diagram of the organization’s network structure.
• Document the numbering plan to be implemented.
• Provide a utilization plan for the following three and six months.

The rest of the applications shall be studied based on the analysis of the documentation justifying the critical and/or key aspects of the project.

All micro-assignments shall be made from address blocks specifically reserved for this type of assignments. LACNIC shall publish the list of these blocks and those micro-assignments already awarded.

4.4.6.Registration assignments

All IPv6 address block assignments of a /48 or larger block made by an ISP to customers connected to their network and users of services provided must be registered on LACNIC's WHOIS database no more than 7 days after the assignment.

The information available in the WHOIS database will also be used by LACNIC when analyzing additional IPv4 address block requests made by the ISP.

The information available in the WHOIS database will be used by LACNIC to calculate the HD-Ratio when analyzing additional IPv4 address block requests made by the ISP.

Assignment registration is also necessary for the following reasons:

. To ensure that the IR has completed or is close to completing address space allocation such that the allocation of additional space is justified.

. To inform the Internet community which organization is using the IPv6 address space, including the point of contact in case of operation problems, security issues, etc.

. To assist in the study of IPv6 address allocation within the region.

4.4.6.1.Required Information

Assignments registered on LACNIC's WHOIS database must include the organization's name; address; administrative contact, technical contact, and contact in case of abuse, with their updated telephone numbers and email addresses.

4.4.6.1.1. Residential Customers

ISPs that provide services to residential customers may register on LACNIC's WHOIS database address blocks that are being used by equipment or customer service areas, by service.

Registered information must specify the service area, address of the ISP's main offices, its administrative contact, technical contact, and contact in case of abuse, including their updated telephone numbers and email addresses.

Assignments must be made in address blocks totalizing the number of customers served in the area or by the equipment.

4.4.6.1.2. Residential Customer Privacy

Residential customers receiving /48 and smaller IPv6 block assignments do not need to have their data registered on LACNIC's WHOIS database.

The ISP whose residential customer receives an IPv6 assignment of a /48 or larger block may choose to register the assignment on LACNIC's WHOIS database by entering its own data or a code used as internal reference. The administrative contact, technical contact, and contact in case of abuse must be those of the ISP.

4.4.7.Reverse Lookup

When an RIR/NIR delegates IPv6 address space to an organization, it also delegates the responsibility to manage the reverse lookup zone that corresponds to the allocated IPv6 address space. Each organization should properly manage its reverse lookup zone. When making an address assignment, the organization must delegate to an assignee organization, upon request, the responsibility to manage the reverse lookup zone that corresponds to the assigned address.

4.4.8.Existing IPv6 Address Space Holders

Organizations that received /35 IPv6 allocations under the previous IPv6 address policy [RIRv6-Policies] are immediately entitled to have their allocation expanded to a /32 address block, without providing justification, so long as they satisfy the criteria in Section 4.4.1.1. The /32 address block will contain the already allocated smaller address block (one or multiple /35 address blocks in many cases) that was already reserved by the RIR for a subsequent allocation to the organization. Requests for additional space beyond the minimum /32 size will be evaluated as discussed elsewhere in the document.

4.5. Mergers, Acquisitions, Reorganizations or Relocations

Because LACNIC's policies do not recognize the non-authorized sale or transfer of assigned or allocated resources, such transfers will be considered invalid.

Nevertheless, LACNIC will process and register any IPv6 resource transfer that occurs as a result of a partial or complete merger, acquisition, business reorganization or relocation, regardless of whether the resources are held by an ISP or an end-user.

To initiate this change and proceed with the registration, legal documentation must be submitted which, at the discretion of LACNIC, supports the operation. Examples of such documentation include:

• A copy of the legal document validating the transfer of assets.
• A detailed inventory of all the assets used by the applicant for maintaining the resources in use.
• A list of the applicant's clients using the resources.

The need to maintain all the resources must also be justified, forcing the return of the surplus resources if applicable or, alternatively, the transfer of such surplus resources to third parties under the policies in force (4.4.1., 4.4.2., 4.4.3. y 4.4.4). When resources are to be returned, LACNIC will determine the corresponding conditions and deadline.

• Policy development
• Policy Manual (PDF version)
• LACNIC POLICY MANUAL (v2.19 - 22/08/2023)
• 0. DEFINITIONS
• 1. GENERAL RULES
• 2. IPv4 ADDRESSES
• 3. ALLOCATION OF AUTONOMOUS SYSTEM NUMBERS (ASN)
• 5. DELEGATION OF REVERSE RESOLUTION
• 6. LAME DELEGATION POLICY
• 7. RESOURCE REVOCATION AND RETURN[2]
• 8. Request for BULK WHOIS
• 9. Global Policies
• 10. Policy for the Allocation of Internet Resources for Research and Experimental Needs
• 11. Policies Relating to the Exhaustion of IPv4 Address Space
• 12. Registration and validation of "abuse-c" and "abuse-mailbox"

• Settings Profile and security information
• Request IPv4 Addresses

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ARIN experienced depletion of its IPv4 Free Pool on 24 September 2015 , however we are still processing and approving customer IPv4 requests. Visit the Waiting List page to learn more about how IPv4 requests are being handled.

You may also consider submitting a transfer request to acquire IPv4 space.

Reserved IPv4 Address Blocks

Since IPv4 depletion, we no longer can fulfill requests for IPv4 addresses unless an organization meets certain policy requirements that reserve blocks of IPv4 addresses for special cases, as outlined below.

Resources allocated from a reserved pool (including those designated in Section 4.4 and 4.10) are not eligible for transfer to specified recipients. Receipt of an allocation from these pools does not affect your eligibility to be on the Waiting List for Unmet Requests , nor will any existing Waiting List request be removed.

Micro-allocation

Policy: NRPM 4.4

ARIN will make IPv4 micro-allocations to critical infrastructure providers of the Internet, including public exchange points, core DNS service providers (e.g., ICANN-sanctioned root and ccTLD operators) as well as the RIRs and IANA. These allocations will be no smaller than a /24. Multiple allocations may be granted in certain situations.

IPv4 Block to Facilitate IPv6 Deployment

Policy: NRPM 4.10

As part of the community-adopted policy, a contiguous /10 IPv4 block has been set aside and dedicated to facilitate IPv6 deployment. Allocations and assignments from this block must be justified by immediate IPv6 deployment requirements. Examples of such needs include: IPv4 addresses for key dual stack DNS servers, and NAT-PT or NAT464 translators. ARIN staff will use their discretion when evaluating justifications.

This block is subject to a maximum size allocation of /24. In order to receive an allocation or assignment under this policy:

• the applicant may not have received resources under this policy in the preceding six months;
• previous allocations/assignments under this policy must continue to meet the justification requirements of this policy;
• previous allocations/assignments under this policy must meet the utilization requirements of end user assignments;
• the applicant must demonstrate that no other allocations or assignments will meet this need;
• on subsequent allocation under this policy, ARIN staff may require applicants to renumber out of previously allocated / assigned space under this policy in order to minimize non-contiguous allocations.

ISP Allocations

ARIN allocates blocks of IP addresses to ISPs for the purpose of reassigning that space to their customers.

For policy information, see Number Resource Policy Manual (NRPM) Section 4.2 .

For fee information, see ARIN’s Fee Schedule .

Initial Requests

Standard / renumbering.

Policy: NRPM 4.2.2

All ISP organizations without direct assignments or allocations from ARIN qualify for an initial allocation of up to a /22, subject to ARIN’s minimum allocation size.

All ISP organizations without direct allocations, direct assignments, re-allocations or reassignments automatically qualify for a /24. These organizations are exempt from requirements of showing the efficient utilization of previously held IPv4 space. These organizations may qualify for a larger than a /24 by documenting how the requested allocation will be utilized within the request size specified in NRPM 4.2.4.3 .

ISPs holding re-allocations and/or reassignments must show the efficient utilization of their resources consistent with the requirements in sections NRPM 4.2.3 and NRPM 4.2.4 .

Documentation typically required for initial requests:

• List of CIDR prefixes/ranges assigned to dynamic pools with service type (e.g., DSL, wireless), city/region served, peak utilization percentage, and number of customers served for each pool
• List of IP addresses/subnets statically assigned to customers along with the corresponding customer name for each IP address/subnet
• List of IP addresses used for web hosting along with at least one customer domain name hosted on each IP address
• List of IP addresses/subnets assigned to internal equipment/infrastructure along with the corresponding hostname/device name for each IP address/subnet

Additional Requests

Policy: NRPM 4.2.4 )

• Demonstrate at least 50% of each of your allocations is efficiently used
• Demonstrate at least 80% of the sum of all allocations is efficiently used
• Provide reassignment information for all customer reassignments of eight or more contiguous IP addresses via SWIP or RWhois
• Provide reassignment information in text or spreadsheet format for all customer assignments less than 8 contiguous IP addresses

Multiple Discrete Networks

Policy: NRPM 4.5

• Demonstrate your organization is a single entity and not a consortium of smaller independent entities
• Provide verification your organization has two or more discretely routed networks
• Provide detailed records on how you’ve allocated space to each discrete network, including the date of each allocation
• Demonstrate 50% utilization of both your last allocation and of all allocations (overall) OR demonstrate all free blocks are smaller than ARIN’s minimum allocation

Third Party Internet Access (TPIA) over Cable

Policy: NRPM 4.2.3.8

IP addresses reassigned by an ISP to an incumbent cable operator for use with Third Party Internet Access (TPIA) will be counted as fully used once they are assigned to equipment by the underlying cable carrier provided they meet the following requirements:

• Initial assignments to each piece of hardware represent the smallest subset reasonably required to deploy service to the customer base served by the hardware
• Additional assignments to each piece of hardware are made only when all previous assignments to that specific piece of hardware are at least 80% used and represent a 24-month supply
• IP allocations used through 4.2.3.8 are non-transferable via section 8.3 and section 8.4 for a period of 36 months. In the case of a section 8.2 transfer the IP assignment must be utilized for the same purpose or needs-based justification at a rate consistent with intended use.

End User Assignments

An end user is an organization that operates a network exclusively for its employees but does not provide Internet services to customers. ARIN assigns blocks of IP addresses to end users who request address space for their internal use in running their own networks, but not for sub-delegation of those addresses outside their organization. End users must meet the requirements described in these guidelines for justifying the assignment of an address block.

For policy information, see Number Resource Policy Manual (NRPM) Section 4.3 .

Size: /24 minimum Policy: NRPM 4.3.2

• End-user organizations without direct assignments or allocations from ARIN qualify for an initial assignment of ARIN’s minimum assignment size
• Provide data demonstrating at least a 50% utilization rate of the requested block within 24 months

Size: /24 minimum Policy: NRPM 4.3.6.1 )

Requirements:

• Provide data showing efficient utilization of at least 50% of each previous assignment
• Provide data showing at least 80% of the sum of all assignments is efficiently used
• Provide data demonstrating a 50% utilization rate of the requested block within 24 months

Documentation typically required for additional requests:

• A brief description of its purpose
• The number of IP addresses currently used
• A brief description of the subnet’s purpose
• Number of IP addresses that will be used within 12 months
• Number of IP addresses projected to be used within 24 months

Submitting Your Request

To better understand how to use ARIN Online to submit a request, visit the Get Started page .

All resource requests require an ARIN Online account linked to either an Admin or Tech Point of Contact record (POC) with the authority to request resources for a valid Organization Identifier (Org ID). For assistance creating a POC record, visit our POC Records page . You may also want to visit our page on Org IDs .

• Log in to ARIN Online.
• Select IP Addresses from the navigation menu.
• Select Request .
• The subsequent windows guide you through your request.

ARIN may require detailed contact information, organization and network information, or business plan details to justify a request. ARIN recommends providing as many details as possible, as detailed justification documents may result in fewer correspondence cycles and a smoother request process. To view some example documentation that may be used as templates when requesting resources, visit the Examples: Resource Request Documentation page .

An ARIN Customer Service Resource Analyst will review your request (typically within two business days) and reply to either approve your request or request more information. Once all requirements are met, ARIN will approve your request and ask that you pay any applicable fees and submit a signed Registration Services Agreement (RSA) within 60 days. Once ARIN receives a signed RSA and all applicable fees, your resources will be issued within two business days.

If you need a status update on your request or have any questions, please call ARIN Registration Services at 703.227.0660. If you need assistance with paying the registration fee or submitting a signed RSA, please call ARIN Financial Services at 703.227.9886.

Out of Region Use

ARIN registered resources may be used outside the ARIN service region for organizations with a real and substantial connection with the ARIN region. For details, please see Number Resource Policy Manual (NRPM) Section 9 . To view the ARIN service region, visit the ARIN Region page .

IPv4 Addressing Options

• IPv4 Addresses Cleared for Waiting List
• IPv4 Waiting List
• Requesting IP Addresses or ASNs
• IPv6 Information
• Understanding the Return and Revocation Process
• Quick Guide to Requesting Resources

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