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What is a Whois Service?
Whois is a query and response protocol that is used for querying databases that store registered users or assignees of an Internet resource, such as IP addresses or domain names.
ARIN's Whois service is a public resource that allows a user to retrieve information about IP number resources, organizations, and Points of Contact (POCs) registered with ARIN. It pulls this information directly from ARIN’s database, which contains IPv4 and IPv6 addresses, Autonomous System Numbers (ASNs), organizations, customer reassignments, and related POCs.
ARIN will not collect any personal information for inclusion in its public Whois. The only information that is published in ARIN’s public Whois is organizational information associated with an Internet number resource, including POC records. The personal information you provide when creating your ARIN Online Profile is kept strictly confidential and is not displayed in your public Whois record.
Note: Some types of information (such as domain information) are not provided by ARIN’s Whois service, but may be available from other Whois services.
There are different ways to get information from Whois, including:
- Web interfaces: ARIN and others provide Whois web interfaces. ARIN provides simple and advanced Whois search capabilities in a search section on our web site.
- Application Programming Interfaces:
- ARIN provides a Whois-RESTful Web Service (Whois-RWS) that allows developers to create their own applications or scripts that retrieve information using Whois-RWS.
- The IETF has standardized a RESTful Whois API called Registration Data Access Protocol (RDAP) that is supported by all Regional Internet Registries (RIRs), including ARIN. More information is available on the RDAP page.
- Command-Line Interface (CLI) clients: You can access Whois information by connecting to a Whois server using CLI commands entered into a terminal window. ARIN’s Whois service is available through the CLI. This page provides instructions for using the CLI method of Whois.
Each RIR maintains its own Whois service for the region that it covers. ARIN’s Whois contains detailed information only about the resources that ARIN manages. However, it also provides reference records for IP address ranges and ASNs associated with other RIRs, including AFRINIC (Africa), APNIC (Asia Pacific Region), LACNIC (Latin America), and RIPE NCC (Europe, Middle East, and parts of Asia), but does not include information on delegations below the RIR level for these ranges. To get more detailed information about resources registered in other regions, you will need to connect to that region’s Whois server.
Also note that the information provided on this site for Whois command syntax, flags, and examples only applies to ARIN’s Whois service.
Entering Your Query
To use Whois from a terminal window, enter your query from the CLI. You can use different flags to restrict your search or display specific output.
Note: Depending on your operating system and terminal program, you may need to enter commands slightly differently. For example, when using Apple OS, you need to surround flags and search terms with quotes, and separate each type of flag with quotes. Quotes are not needed when using UNIX terminals.
Submitting a Whois Query from a Terminal
To submit a Whois query from a terminal, enter:
whois -h whois.arin.net “flagsearch-term”
The parts of this command are:
- whois: the command itself
- -h: specifies that the hostname of the Whois server will follow
- whois.arin.net: the name of ARIN’s Whois server
- flag: narrows the search by restricting the results to those that match criteria designated by the flag (see the following table)
- search-term: the information for which you are searching
You may use flags with the query to narrow down the search criteria. Depending on the terminal client, you may not have to include quotes around the flag and/or search term. If you do not include a flag, the Whois server attempts to guess what information you are looking for and parses the query.
The flags to restrict the records are listed in the following table. Flags must be separated from each other and from the search term by a space. You can only use one flag of each type in a query (for example, one record type, one attribute, or one display flag).
In this table, all examples assume that the user is on a Mac and entering commands within the terminal app window.
Searches for the specified network address space.
|whois -h whois.arin.net “n 198.51.100.0”|
|r||Record Type||Searches for the specified network address space in CIDR notation. If a hierarchy (<, >, or =) is not used, the Whois server attempts to guess the range of results desired.|
whois -h whois.arin.net “r = 198.51.100.0/24”
whois -h whois.arin.net “r > 198.18.0.0/15” “r < 198.51.100.0/24”
|d||Record Type||Searches for the delegation name (information that is entered when configuring Reverse DNS).||whois -h whois.arin.net "d 28.4.199.in-addr.arpa."|
|a||Record Type||Searches for the specified ASN.||whois -h whois.arin.net “a 26299”|
Searches for the specified Points of Contact (POCs). For example, the query at right searches for POCs with the name Smith.
whois -h whois.arin.net “p smith”
|o||Record Type||Searches for the specified organization.||whois -h whois.arin.net “o *Philadelphia*”|
|c||Record Type||Searches for the specified end user customer. If you know the customer ID, you can use it with the customer query to narrow down results and display information for only that customer (see 2nd example).|
whois -h whois.arin.net “c arin”whois -h whois.arin.net "c C02366807"
|e||Record Type||Searches for the specified POC, organizations, and end user customers.|
whois -h whois.arin.net "e icann"
|z||Record Type||Searches the database with all of the previously-listed flags (n, r, d, a, p, o, c, and e).||whois -h whois.arin.net “z icann”|
|@ domain-name||Record Attribute||Limits the query results to those containing the specified domain name in an email address. For example, the query at right searches for the domain name arin.net in the POC, organizations, and end user customers.||whois -h whois.arin.net “e @ arin.net”|
|! handle||Record Attribute||Limits the query results to those containing the specified handle or identifier of the POC. Searching for the handle can deliver more accurate results than an email or name search. For example, the query at right searches for the organization named ICANN with a handle containing IANA.||whois -h whois.arin.net “o icann ! iana”|
|/ name||Record Attribute||Limits the query results to those containing the specified name.||whois -h whois.arin.net "n / IANA-V6-RESERVE2"|
|. name||Record Attribute||This flag has the same function as the / name flag, but can be used when performing searches on Whois clients that do not work well with / name.|
Searches that retrieve a single record will display the full record. Searches that retrieve more than one record will be displayed in list output. You can use the + and - flags to modify the output if a query retrieves more than one record.
Using this flag in the query requires that full output is displayed with detailed information for each match.
|whois -h whois.arin.net "+ n / TEST-NET-1"|
|-||Using this flag in the query requires that list output is displayed with summary information only (even if a single record is returned).|
whois -h whois.arin.net "e - icann"
Records in ARIN’s Whois have hierarchical relationships with other records. For example, a network can have parent networks and child networks. To display those related records, use the flags described as follows. (Note: The + flag cannot be used with these flags.)
Displays the record related moving up the hierarchy. For a network, displays the supernet, or parent network, in detailed format.
|whois -h whois.arin.net "n < 198.51.100.55"|
|>||Displays the record related moving down the hierarchy. For a network, displays the subdelegations, or subnets below the network, in list format. For an organization or customer, displays the resources registered to that organization or customer, in list format.|
whois -h whois.arin.net "n > 192.0.0.0"
|=||Displays only an exact match in the hierarchy.|
To perform a wildcard query, substitute an asterisk (*) for the alphanumeric characters that you want to leave off the end of the query term. For example, this query performs a search for POCs beginning with or equal to North, and would also return results with Northcutt, Northington, Northrup, etc.:
whois -h whois.arin.net “p north*”
Wildcards can be used with any other flags.
Additional Search Tips
- To guarantee matching only a single record, look it up by its handle using a handle-only search. In the record summary line, the handle is shown in parentheses after the name.
- When using a handle to conduct a search for POC information, be sure to add the -ARIN extension.
- Queries that return more than 256 results will stop displaying data after the limit has been reached for each record type. You may want to narrow your search criteria or add flags to your query to limit the results.
- To search on an individual's name, you can enter the last name, or to further restrict results, use the last name and first name, separated by a comma. (For example: Smith, John.)
Interpreting Whois Results
Results for Whois queries performed using the ARIN website or the command-line interface contain information about IPv4 and IPv6 address space, ASNs, POCs, and Orgs. Depending on the flags used in the query, the fields shown in the tables below may or may not be displayed in the result. Some fields appear in results from multiple query types; these are listed in the “Common Fields” section.
Network records (NETs) define a range of IPv4 or IPv6 addresses and show the organizations and POCs with authority over them.
|NetRange||IP address range of a network resource.|
|CIDR||The IP address specified in CIDR notation.|
|NetName||Name given to the network by the organization.|
|NetHandle||A unique auto-generated handle that identifies the network in ARIN’s database. It cannot be changed.|
|Parent||The NetName and NetHandle of the parent IP address range.|
|NetType||The type of network: |
|Origin AS||Optional field collected during all IPv4 and IPv6 block transactions that records a list of the Autonomous System Numbers (ASNs), separated by commas or whitespace, from which the addresses in the address block(s) may originate.|
Organization information includes the Org ID to which resources are registered and the contact information for the Org POCs.
|Organization/OrgName||The name of the Organization who is assigned the resource(s)|
|OrgId||A unique auto-generated name that identifies the organization in ARIN’s database. It cannot be changed.|
|AdminHandle||A unique auto-generated handle that identifies the Admin POC for this org in ARIN’s database. It cannot be changed.|
|AdminName||Name of the Admin POC for the org.|
|AdminPhone, AdminEmail||Phone number and email address for the Admin POC for the org.|
|TechHandle||A unique auto-generated handle that identifies the Tech POC for this org in ARIN’s database. It cannot be changed.|
|TechName||Name of the Tech POC who manages the org.|
|TechPhone, TechEmail||Phone number and email address for the Tech POC for the org.|
|AbuseHandle||A unique auto-generated name that identifies the handle of the Abuse POC for this org in ARIN’s database. It cannot be changed.|
|AbuseName||Name of the contact for the reporting and resolution of network abuse issues.|
|AbusePhone, AbuseEmail||Phone number and email address for the Abuse POC for the org.|
ASN records, much like NET records, display the specific ASN and the Org with authority over it.
|ASNumber||Displays the number that represents an autonomous system—networks or connected groups of networks that adhere to a single unique routing policy that differs from the routing policies of their border peers.|
|ASName||Name given to the ASN by the organization.|
|ASHandle||Number used to identify the AS in the ARIN database. Typically consists of the prefix AS and the AS number (for example, AS26299).|
Point of Contact
POC information provides a name, mailing address, and contact information, and lists any organizations or resources over which the POC has authority.
|Name||The name of the POC.|
|Handle||A unique auto-generated handle that identifies the POC in ARIN’s database. It cannot be changed.|
|Company||Company for which the person is the POC.|
Delegations are entries that relate IP addresses to domain names using the Domain Name System (DNS) of the Internet. Delegations contain the information necessary for Reverse DNS, including the associated nameservers, and DNS Delegation Signer (DS Record) information.
|Name||The name of the POC.|
|NameServer||The name of one or more nameservers for a domain object. There can be multiple nameservers shown.|
Common Fields Found on Multiple Record Types
These fields may display in the results of multiple types of queries.
|Address, City, StateProv, PostalCode, Country||Typically the location information for a resource, an organization, or POC. May not always reflect the exact physical location of the actual resource, org, or POC, as there is no policy requirement to do so.|
|RegDate||Date that the resource was initially registered in the ARIN database.|
|Updated||Date that the registration record was last updated.|
|Comments||Text comment that applies to the resource. There can be multiple Comment fields displayed in a result. These comments are typically added by an organization POC. Comments can include: |
|Ref||URL of the information as it appears in ARIN’s database. It can have a prefix appended to indicate the type of reference. For example, this is a URL for the Org Tech POC that is shown in a result: |
Getting Help with Whois
- For operational problems with Whois, please contact firstname.lastname@example.org with the appropriate details.
- To report inaccurate information in Whois, you can file a report online.
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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
- 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 with no intention of splitting the block up among its customers, this is known as an assignment.
Note: Reallocations and reassignments may only be made from an allocation.
Note: ASNs are assigned individually by ARIN and may not be allocated.
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).
Simple vs. Detailed Reassignments
Simple reassignments are those where the customer does not need to maintain their own in-addr.arpa delegation, display their own 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.
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 Points of Contact (POCs) are authoritative over those resource records.
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: 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: 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. More information is provided in the API documentation for ARIN’s RESTful web service. (Note that this method requires using an API key obtained from ARIN Online.)
- Email Templates: ARIN customers have the option of sending a completed email form, or template, to email@example.com 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, which may be found on the this page. 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 that this method requires 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. Every individual who manages organization or resource records should create an ARIN Online account using an individual email address. Unlike POC records, ARIN Online accounts cannot use role email addresses, nor should they be shared, or transferred to another person. ARIN Online accounts are portable, and registered users can continue to use their accounts when they move or change jobs because accounts can be unlinked from POC, organization and resource records. In order to create an ARIN Online account, just visit ARIN's homepage (www.arin.net) and click “new user?” above the login boxes on the left side of the page.
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. API Keys are created within ARIN Online by logging in and selecting Your Account > Settings from the navigation menu. In the Security Info section, choose Manage API Keys from the Actions menu.
Create a POC and Give it Authority
Before reporting reallocation/reassignment data, the user's 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 the user has an ARIN Online account linked to a POC with proper authority over that record. For more information on creating POCs, click here.
Once a user creates or finds the right POC in ARIN's database, that POC must be linked to the user's ARIN Online account. This may be done while logged into ARIN Online by clicking Your Account > Point of Contact records on the left and selecting “link to it” within the top section of the page. This allows the user to select a POC record matching your account information and link it to their ARIN Online account. For more information on linking an ARIN Online account to a POC, click here.
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. For information regarding ORG creation, click here.
Reporting Reassignments Using ARIN Online
To reassign network address space, you have the following options:
Option 1: View free blocks and reassign:
- 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.)
- In the list of networks, choose the network space that you want to reassign.
- Choose the size of the CIDR block to reassign, then choose Reassign.
Option 2: View networks and enter a range to reassign:
- From the Dashboard, under Account Snapshot, choose Networks 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.)
- 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.
- Choose Reassign. After choosing Reassign, follow the steps in the subsequent screens to complete the reassignment.
Tip: Copy the Network Address so that you can easily enter it later in the Reassignment Details screen.
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.
First, find the network that was reassigned by selecting IP Addresses > Search from the navigation menu. Be sure that you’ve selected the option to include the networks that you’ve reassigned.
To delete a directly reassigned NET:
- In the list of search results, expand the informational panel for the NET.
- 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.
- 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:
- In the list of search results, click the Network Name (for example, NET-DEV-001) to open the View and Manage Networks page for that NET.
- Choose Delete Reassignments. A list of the reassignments is displayed.
- Choose an individual network by clicking on the Network Name.
- In the View and Manage Network page, choose Delete.
Caution: You can’t undo this deletion.
Reporting Reassignments Using Email Request Forms
The process for using email requests 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 reassigns cannot be performed using email request forms.
Which request form do I use when utilizing REST 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.
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.
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.
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.
Used to subdelegate IP addresses to a customer that does not need to:
- subdelegate the addresses to their own customers
- maintain their own in-addr.arpa delegation
- display their own point of contact (POC) information.
It 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 reassigns are only available in 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 22.214.171.124.3.2 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.