Using our WHOIS Server

We provide a WHOIS server at for looking up information for a number of registries maintained as part of the IANA functions:

  • Root Zone Registry — the WHOIS database of delegations from the DNS root zone (also know as top-level domains).
  • .INT Registry — the database of .INT domain registrations, used by intergovernmental treaty organisations.
  • .ARPA Registry — the database of .ARPA domain registrations
  • IPv4 and IPv6 allocations — the registry of allocations made from the global IPv4 and IPv6 address spaces, plus specially designated allocations described in technical standards.
  • Autonomous System (AS) number allocations — the registry of allocations made from the global AS number space.

Queries supported

Here are some illustrative examples of queries supported by the WHOIS Server:

Query type Examples
Domain names, .org,
IP addresses,
IP address ranges,, 192/24
AS numbers 542, AS542

The WHOIS server does not support any specific flags or options beyond the query argument.

Response format

Data is returned in a colon delimited "key: value" format. Comment lines begin with a "%" symbol. Text is encoded using UTF-8.


If our WHOIS server determines there is a more specific answer to the query you have received, it will return the most specific answer it has available. If we know of a WHOIS server that should be more authoritative for the specific record, we also return a "refer:" line. You may wish to send a WHOIS query to that server to find more information about the resource.

This behaviour occurs, for example, if you query for a domain like "". The root zone database only has authoritative data for ".org", but we will provide a referral to the .org WHOIS server which has more information about the second-level registration. Such behaviour will also happen for IP address allocations that are more specific than the records in IANA's databases.