Reporting Reassignments

The Big Picture

Before using or designing software to manage records within ARIN’s database, it is important to understand ARIN’s relational database, and how ARIN maintains records and interacts with customers.

IP Address and Autonomous System Number (ASN) Distribution

ARIN is one of five Regional Internet Registries (RIRs). RIRs are nonprofit corporations that administer and register IP address space and ASNs within defined regions. RIRs receive address space in large blocks from the Internet Assigned Numbers Authority (IANA), and allocate smaller address blocks to organizations within their regions. These organizations then assign IP addresses to consumers.

Allocations vs. Assignments

A flowchart showing how allocations and assignments relate to organizations and customers

  • When ARIN registers a block of IP addresses to a customer planning to register pieces of that block to its own customers, this is known as an allocation.
  • When ARIN registers a block of IP addresses to an entity who has no intention of splitting the block up among its customers, this is known as an assignment.

When an ARIN customer registers a piece of their allocation to a customer of their own, this is known as a reallocation or reassignment, depending on whether their customer intends to register pieces of that block to customers of their own (reallocation) or if it is intended for internal use (reassignment).

Note: Reallocations and reassignments may only be made from an allocation.

Autonomous System Numbers (ASNs)

ASNs are assigned individually by ARIN and may not be allocated.

Simple vs. Detailed Reassignments

Simple reassignments are those where the customer does not need to maintain their own delegation, display their own Point of Contact (POC) information, or divide their address space further among their own customers. A detailed reassignment is one in which the customer does not need to further divide the space, but does need to maintain its own reverse name servers and/or display separate POC information.

Note: Incidental or transient use of address space by third parties is not considered a reassignment.

Resource Requests

In order for ARIN to properly register Internet number resources to organizations within its region, those organizations submit a resource request, stating which type of resources they need, and how they intend to use them. ARIN requires that requests include utilization plans, so that ARIN can allocate them fairly among organizations as they continue to expand their networks and customer bases.

Keeping Track of Who Uses What

ARIN maintains a database that contains detailed records of which resources have been allocated and assigned, as well as which organizations and POCs are authoritative over those resource records.

Reporting Reassignments


When an organization reassigns address space, they report reallocation/reassignment information to ARIN. This information is vital, as ARIN makes allocations based on an organization’s utilization history, projected requirements, and other information. While initial allocations may be relatively small, subsequent allocation sizes are scaled based partially on growth shown via reallocation/reassignment information received by ARIN.

ARIN requires organizations to submit information for all IPv4 reassignments of /29 and larger and IPv6 reassignments of /64 or shorter prefix within seven days of the subdelegation. For IPv4 blocks of /30 or longer prefix, ISPs may choose to provide utilization data using one of the methods described on this page or manually upon request. There are special reporting requirements for residential cable ISPs and residential customers. Organizations may only submit reassignment data for records within their allocated blocks. ARIN may request reassignment/reallocation information at any time. If the organization does not supply the information, ARIN may withhold future allocations, and in extreme cases, existing allocations may be affected.


ARIN customers have two options when it comes to reporting their reallocation/reassignment data. They can use Referral Whois (RWhois) or the Shared Whois Project (SWIP).


RWhois is an extension of the original Whois protocol and service. It focuses on the distribution of data representing networks and POCs, and uses the inherently hierarchical nature of these network objects (domain names, IP networks, email addresses) to more accurately discover the requested information. RWhois allows organizations to advertise their reallocation/reassignment from an internal server, rather than actively sending it to ARIN. There are numerous requirements for using this sort of distribution server for reallocation/reassignment information, including 24 / 7 server functionality, response qualification, and continuity of data. For details, see Section 3.2 of ARIN’s Number Resource Policy Manual (NRPM). More information about this method is available on the Referral Whois (RWhois) page.


SWIP is a process whereby ARIN customers report reallocation/reassignment data using one of the following methods:

  • ARIN Online: ARIN Online provides a graphical user interface to ARIN’s registration database.

  • Reg-RWS: Registration Representational State Transfer (REST)ful Web Service (Reg-RWS) provides a secure and efficient method for interacting with ARIN’s database. Reg-RWS is most handy for repetitive, mundane tasks done in high volume with no needed human communication, such as SWIP. In addition to being more secure than email templates, Reg-RWS allows for the retrieval of information about a record immediately before submitting changes to it. Reg-RWS also returns a predictable response that can be interpreted and reacted to by automation software.

Note: Reg-RWS requires using an API key obtained from ARIN Online.

Email Request Forms (Templates)

ARIN customers have the option of sending a completed email form, or template, to to report reallocation/reassignment information. There are templates for creating, editing, and removing subdelegations (allocations and assignments made from an allocated block of address space), both for IPv4 and IPv6 networks. While email templates are an automatable way to report reassignment information and make the appropriate changes within ARIN’s database, Reg-RWS is a more secure and direct method.

Note: Email templates require using an API key obtained from ARIN Online.)

Before You Get Started

Create an ARIN Online Account

Your first step is to create an ARIN Online account.

Create an API Key

After creating your account and logging in to ARIN Online, you need to create an API key to be able to report reassignment/reallocation information by email template or Reg-RWS. An API key provides a means of secure communication with ARIN.

Create a POC and Give it Authority

Before reporting reallocation/reassignment data, your ARIN Online account must have the authority to do so. ARIN’s Reg-RWS and email template system will not process any modifications to a database record unless you have an ARIN Online account linked to a POC with proper authority over that record. Visit Creating a POC for more information.

After you create or find the correct POC in ARIN’s database, that POC must be linked to your ARIN Online account. Visit Linking a POC to Your ARIN Online Account for more information.

Finally, you will need to create or find the appropriate Org to add your POC to it as an Admin and/or Tech POC. This allows your POC (and your ARIN Online account) to make changes to ARIN’s database regarding your ORG and any resources attached to it. Visit Creating an Org ID for more information.

Reporting Reassignments Using ARIN Online

Creating Reassignments

To reassign network address space, you have the following options:

Option 1: View free blocks and reassign:

  1. Choose IP Addresses > Reassign Addresses from the navigation menu. A list of unassigned address space is displayed. (Note that users with over 11,000 NETS will not see this list. See the note at the end of the Creating Reassignments section.)
  2. In the list of networks, choose the network space that you want to reassign.
  3. Choose the size of the CIDR block to reassign, then choose Reassign.

Option 2: View networks and enter a range to reassign:

  1. From the Dashboard, under Account Snapshot, choose Networks (NETs) to access the View and Manage Your Networks page. A list of NETS associated with you is displayed. (Note that users with over 11,000 NETS will not see a list of associated NETS. See the note at the end of the Creating Reassignments section.)
  2. In the list of networks, expand the informational panel for the network portion that you want to reassign. The actions available to you (depending on permissions and resources) appear under NET Actions.

Tip: Copy the Network Range so that you can easily enter it later in the Reassignment Details screen.

3. Choose Reassign. After choosing Reassign, follow the steps in the subsequent screens to complete the reassignment.

Note for Users With 11,000 or More Associated NETS

  • Choosing IP Addresses > Reassign Addresses will not provide the list of free blocks. You’ll need to enter the IP address in the IP Address Range field in the Reassignment Details page and follow the instructions in the subsequent screens.
  • Choosing IP Addresses > Search will not display a list of NETS associated with you. You’ll need to enter an IP address in its entirety and choose Search to display it.

Deleting Reassignments

First, find the network that was reassigned by selecting IP Addresses > Search from the navigation menu. Be sure that you have selected the option to include the networks that you have reassigned.

To delete a directly reassigned NET:

  1. In the list of search results, expand the informational panel for the NET.
  2. Under NET Actions , choose Delete to open the Delete Network page. The page provides information about the reassigned space and any contained reassignments of this space that were made.
  3. Choose Delete to remove the NET. Any additional reassignments that were made after the initial reassignment are also removed.

Caution: You can’t undo this deletion.

To remove individual reassignments from a list of reassignments of a space:

  1. In the list of search results, click the Net Handle (for example, NET-DEV-001) to open the View and Manage Networks page for that NET.
  2. From the Actions menu, choose Delete Reassignments. A list of the reassignments is displayed.
  3. Choose an individual network by clicking on the Network Name.
  4. In the View and Manage Network page, choose Delete.

Caution: You can’t undo this deletion.

To delete all reassignments under a network:

  1. In the View & Manage Network page, the Reassignments section displays the number of reassignments if there are more than one.
  2. In the View & Manage Network page, under Actions, choose Delete Reassignments. A list of the reassignments is displayed.
  3. Choose Delete All Reassignments.
  4. Confirm the deletion.

Caution: You can’t undo this deletion.

Reporting Reassignments Using Email Request Forms (Templates)

The process for using email request forms is detailed below. You must include the API key in the request form or send it from the email address associated with the API key to authorize processing.

Note: IPv6 simple reassignments cannot be performed using email request forms.

Which request form do I use to create reassignments?

Since ARIN distinguishes reallocations from reassignments, it is important that you submit subdelegation information using the correct request form. If you submit reassignment information using the IPv4 Reallocate, IPv6 Reallocate, IPv4 Reassign-Detailed, or IPv6 Reassign request forms, the downstream organization must have a unique alphanumeric identifier (an Org ID). An Org ID can be created using the Reallocate or Reassign-Detailed request forms or using the organization request form.

There are multiple IPv4 and IPv6 request forms used to report reassignment information. Read the following descriptions to determine which you should use.

  • IPv4 NET-MOD and IPv6 NET-MOD: Used to remove subdelegations originally created using the reassign-detailed or reallocate request forms or to return a block of directly registered IP addresses. To remove subdelegations, the request must be submitted with an API key associated with an ARIN Online user account linked to the upstream organization’s Admin or Tech POC or the upstream’s Tech POC for the resource. These are also used to modify a network that is not a simple reassign.

  • IPv4 Reallocate and IPv6 Reallocate: Used to subdelegate IP addresses to a downstream organization that will further subdelegate the IP addresses to their own customers. These requests must be submitted by an ARIN Online user account linked to the parent organization’s Admin or Tech POC, or the Tech POC for the resource.

  • IPv4 Reassign-Detailed and IPv6 Reassign: Used to subdelegate IP addresses to a downstream organization that does not need to further subdelegate the IP addresses, but does need to maintain its own reverse name servers and/or display separate point of contact (POC) information. It is submitted by an ARIN Online user account linked to the parent organization’s Admin or Tech POC, or the Tech POC for the resource.

  • IPv4 Reassign-Simple: Used to subdelegate IP addresses to a customer that does not need to:

    • subdelegate the addresses to their own customers
    • maintain their own delegation
    • display their own point of contact (POC) information

The reassign-simple template can also be used to change the customer name and address information (but not the range) on an existing simple reassignment and to remove simple reassignments. It is submitted by an ARIN Online user account linked to the parent organization’s Admin or Tech POC, or the Tech POC for the resource.

Note: IPv6 simple reassignments are not available using request forms/templates; this functionality is only available in ARIN Online or through the RESTful web service.

POCs are not associated with simple reassignments. The customer receiving the reassignment will have the assigning upstream’s POCs and name servers.

Special Reporting Requirements

Residential Access ISPs

For organizations that have residential subscribers and assign address space to their access infrastructure to which their customers connect rather than to individual subscribers, IPv4 assignment information regarding each market area holding an address block should be submitted to ARIN using one of the methods described in this page, with the network name used to identify each market area. Residential access ISPs must show that they have reassigned at least 80% of their current IPv4 address space, with a 50 to 80% utilization rate, in order to request additional addresses.

Each IPv4 assignment to a specific end-user (if holding /29 and larger blocks) requires the submission of a SWIP request form or use of an RWhois server. Requesters will also be asked to provide detailed plans for use of the newly-requested space.

Residential Customer Privacy

NRPM allows organizations to privatize reassignment information for downstream end-user customers that are individuals, not organizations, and receive service at a place of residence for personal use only. ARIN recommends using version 5 templates to privatize residential customer information. Version 5 templates allow the ISP to submit customer name and street address information for all customers, with a private flag available to designate which records are residential customers that should be private. Records designated as “private” will have the customer name and street address removed when displayed in Whois. ISPs must still provide the customer’s actual city, state, postal code, and country code.

ISPs using this policy must have accurate upstream Abuse and Technical POCs visible on the Whois record for the IP address block from which the addresses are being subdelegated.

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