Using Whois

What is a Whois Service?

ARIN offers public access to ARIN registration data via a number of services. Traditionally, these services are known in the industry as “Whois” in reference to the public data service of the ARPANET, precursor of today’s modern Internet. Whois services are offered by all the Regional Internet Registries (RIRs), most Internet Routing Registries (IRRs) and most domain name registries and registrars. The Whois protocol, (originally specified in RFC 3912), 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. Whois is often referred to as “port 43” in reference to the TCP port number assigned by the Internet Assigned Numbers Authority (IANA) for the Whois protocol, and to differentiate it from other ways of getting Whois data.

ARIN’s Whois

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.

Each Regional Internet Registry (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.

ARIN provides access to Whois data through the following methods:

The information provided on this site for Whois search functions, command syntax, flags, and examples only applies to ARIN’s Whois/RDAP and Whois-RWS services and not Whois services provided by any other entity.

There are different ways to get information from ARIN’s Whois; the following sections provide more information.

Using Whois Web Interfaces

ARIN and other entities provide Whois web interfaces. These provide simple and advanced Whois search capabilities. To use ARIN’s web interfaces, refer to the instructions in the following sections.

Using the Combined “Search Site or Whois” Feature

Enter the information you want to search Whois for into the search box (labeled Search Site or Whois).

screen capture showing the combined search field


ARIN sends your query to search.arin.net, and returns results based on the type of search it guesses you were trying to perform. If you enter a search term that has a specific format, such as an IP address (for example, 2001:500:11::) or an ASN (for example, AS64496), the search engine automatically performs a Whois query and brings you the results.

If the search engine thinks you are searching for information about subject areas on the web site (for example, policy, services, or ARIN functions), it returns results from www.arin.net (you can then choose the Search ARIN’s Whois instead link on the results page to perform a Whois query), as shown in the following example.

screen capture showing search ARIN's whois instead


The Whois part of the combined search function uses Registration Data Access Protocol (RDAP). Visit the RDAP page for more information on the protocol.

Searching for an IP Address

Enter an IP address (for example, 2001:500:11::) in the Search Site or Whois field. You cannot use wildcards (asterisks) with an IP address search in ARIN Whois/RDAP.

screen capture showing an ip address in the combined search field


The search engine auto-detects that you are searching for an IP address and the network and related entities information for that IP address is returned.

screen capture showing results from searching on an ip address


You can use the IP Address or CIDR Range search filter to narrow your search results.

Searching for a CIDR Range

To search on a CIDR range, enter the CIDR (in this example, 12.0.0.0/8) into the search field and choose Search. You cannot use wildcards (asterisks) with a CIDR search in ARIN Whois/RDAP.

The search filter defaults to “automatic” and returns results based on the type of search that the search function guesses you were trying to perform. Due to the format of the search term, the search engine auto-detects that you are searching for a CIDR range and the network and related entities information for that CIDR range is returned.

screen capture showing results from searching on a CIDR range


You can use the IP Address or CIDR Range search filter to narrow your search results.

Searching for an ASN

To search for an ASN, enter the number (with the prefix AS); for example, AS64496. You cannot use wildcards (asterisks) with an ASN search in ARIN Whois/RDAP.

screen capture showing searching on an ASN


Due to the unique naming convention for ARIN-issued ASNs, the search engine auto-detects that you are searching for an ASN and the information for the ASN is returned.

screen capture showing results for asn search


You can use the ASN or Autnum search filter to narrow your search results.

Searching for a POC

To search for a specific POC, enter the POC handle into the search field and choose Search. (A POC handle is the auto-generated alphanumeric ID assigned to a POC record by ARIN Online; for example, KOSTE-ARIN.) The search filter defaults to “automatic” and returns results based on the type of search that the search function guesses you were trying to perform. In this example, the search engine auto-detects that you are searching for a POC handle and returns information about the POC. You cannot use wildcards (asterisks) with a POC search in ARIN Whois/RDAP.

screen capture showing results from searching on a POC handle


You can use the Entity search filter to narrow your search results.

Using a Search Filter

To search for information in a specific field from ARIN’s Whois database, you can choose Search Filter and select from the fields in the Set query type section. See the following sections for more information.

Searching with the “Entity” Filter

Choosing this option searches Whois for an “entity,” which can be a Handle or ID for a Contact, POC, Organization ID (Org ID), or Maintainer (in the Internet Routing Registry) that matches the search term you entered. You cannot use wildcards (asterisks) with an entity search in ARIN Whois/RDAP. Handles typically have the following formats:

  • Org Handle, or Org ID: All capital letters (for example, IANA); may contain a dash and suffix (for example, AKAMA-36)
  • POC Handle: All capital letters with a -ARIN suffix (for example, KOSTE-ARIN)
  • Customer Handle: All capital letters with a CO prefix (for example, C00975227)

The following example shows the results of a search for a POC with the Entity filter selected.

screen capture showing results from searching on an entity


Searching with the “Entities by Full Name” Filter

Choosing this option performs a Whois/RDAP search in the Full Name field for the search term you entered. If you are not sure of the exact full name, you can use wildcards (asterisks) to substitute for missing information. For example, if you want to search for an organization that you know informally as “Yahoo,” searching on Yahoo* would return results with full names of Yahoo, Yahoo Finance, Yahoo Inc., Yahoo! Broadcast Services, Inc., etc.

Searching with the “Domain” Filter

Choosing this option searches for an in-addr.arpa or ip6.arpa domain (sometimes referred to as an inverse address domain) that matches the search term you entered (for example, 154.54.in-addr.arpa). These domains are used in reverse DNS, where an IP address is resolved to a hostname. The in-addr.arpa and ip6.arpa domains are entered into a registration database when reverse DNS is configured for IP addresses held by an organization. You cannot use wildcards (asterisks) with a domain search in ARIN Whois/RDAP.

Searching with the “IP Address or CIDR Range” Filter

To narrow your search and query only in the IP address or CIDR range fields of Whois/RDAP, choose Search Filter and select IP Address or CIDR range. You cannot use wildcards (asterisks) with an IP address or CIDR search in ARIN Whois/RDAP.

The following example shows the results of a search for an IP address with the IP Address or CIDR Range filter selected.

screen capture showing whois/rdap search with ip filter


Searching with the “ASN or Autnum” Filter

To narrow your search and query only in the ASN field or the Autnum field (in the routing templates) of Whois/RDAP, choose Search Filter and select ASN (Autonomous System Number or Autnum).

The following example shows the results of a search for an ASN with the ASN or Autnum filter selected.

screen capture showing results from searching on an asn


Searching with the “Origin AS” Filter

Choosing this option performs a Whois/RDAP search for the Origin Autonomous System (AS) matching the search term you entered. Do not include the AS prefix. For example, to search for AS1895 in the Origin AS field, use 1895. You cannot use wildcards (asterisks) with an Origin AS search in ARIN Whois/RDAP.

To prevent performance issues, an Origin AS query limits the returned networks to 256.

Tips and Helpful Information for Searching in Whois/RDAP

  • Search terms are not case-sensitive.
  • You can use wildcards (asterisks) to search on partial information for full name searches. Substitute an asterisk for the missing part of the information you enter. You can use one or more wildcards at the beginning, middle, or end of your search term. Wildcards can only be used in automatic searches if the system determines you are searching for a full name. For example, the system will not search entities, in-addr.arpa or ip6.arpa domains, IP addresses, CIDR ranges, ASNs, or Origin AS fields using wildcards in ARIN Whois/RDAP.

Searching from “whois.arin.net” (Whois-RWS)

As of March 2019, ARIN’s featured Whois search service is Whois/RDAP. However, the older Whois-RWS is still available. Visit whois.arin.net and enter your search term in the search field. Visit the Whois-RWS FAQ for more information.

Using Whois Application Programming Interfaces (APIs)

  • RDAP: RDAP is a Whois alternative for querying resource registration data. When you use RDAP to query registration data, responses are delivered in JavaScript Object Notation (JSON) format. You can use RDAP clients or scripts to get information via RDAP. More information about the RDAP API is available on the RDAP page.
  • Whois-RWS: ARIN’s implementation of Whois-RWS allows developers to create their own applications or scripts that retrieve information using Whois-RWS. Visit Whois-RWS API Documentation for more information.

Using Command-Line Interface (CLI) Clients with Whois-RWS

ARIN supports searching Whois-RWS using a CLI. Visit Searching Whois Using a CLI.

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 query options chosen or query flags used, the fields shown in the following tables 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 Found on Multiple Record Types section.

Network Information

Network records (NETs) define a range of IPv4 or IPv6 addresses and show the organizations and POCs with authority over them.

Result Field Description
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: Direct Allocation (ISP), Direct Assignment (End user), Reallocated (downstream ISP customer), Reassigned (end user customer)
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

Organization information includes the Org ID to which resources are registered and the contact information for the Org POCs.

Result Field Description
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 Information

ASN records, much like NET records, display the specific ASN and the Org with authority over it.

Result Field Description
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.

Result Field Description
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.

Delegation/Reverse DNS

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.

Result Field Description
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.

Result Field Description
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: Customer comments, Org comments, Resource comments, POC comments
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: OrgTechRef: https://whois.arin.net/rest/poc/IANA-IP-ARIN

Getting Help with Whois

  • For operational problems with Whois, please log in to your ARIN Online account and create an Ask ARIN ticket, or contact the ARIN Help Desk with the appropriate details.
  • To report inaccurate information in Whois, you can file a report online.