7 March 2017

How to test a Whois server by using telnet

Whois is a very simple text-based protocol. It has traditionally been used to retrieve information about domain names and related resources, but a Whois server can also be implemented to provide other information.

To use the Whois protocol, the client connects to port 43/tcp on the server and sends a request, which is terminated by ␍␊. As the protocol is so straightforward, the value added by dedicated Whois clients and by web-based lookup services is often minor. As long as your firewall allows outbound traffic on port 43/tcp and you know the host name of the Whois server, you should be able to do nicely with a telnet client (most popular operating systems include one).

What you need

  • The host name of the Whois server (for use in the telnet command)
  • A string of text for which to request information

What to do

The initial telnet: > symbolises your shell prompt.

telnet: > telnet whois.internic.net nicname
telnet: Trying
telnet: Connected to whois.internic.net (
telnet: Escape character is '^]'.
client: anta.net
server: Whois Server Version 2.0
server: Domain names in the .com and .net domains can now be registered
server: with many different competing registrars. Go to http://www.internic.net
server: for detailed information.
server:    Domain Name: ANTA.NET
server:    Whois Server: whois.domaininfo.com
server:    Referral URL: http://www.domaininfo.com
server:    Name Server: NS.NEBULA.FI
server:    Name Server: NS2.NEBULA.FI
server:    Status: clientDeleteProhibited
server:    Status: clientTransferProhibited
server:    Status: clientUpdateProhibited
server:    Updated Date: 02-oct-2010
server:    Creation Date: 24-sep-1998
server:    Expiration Date: 23-sep-2013
server: >>> Last update of whois database: Sun, 03 Oct 2010 18:33:59 UTC <<<
server: NOTICE: The expiration date displayed in this record is the date the 
server: registrar's sponsorship of the domain name registration in the registry is 
server: currently set to expire. This date does not necessarily reflect the expiration 
server: date of the domain name registrant's agreement with the sponsoring 
server: registrar.  Users may consult the sponsoring registrar's Whois database to 
server: view the registrar's reported date of expiration for this registration.
server: TERMS OF USE: You are not authorized to access or query our Whois 
server: database through the use of electronic processes that are high-volume and 
server: automated except as reasonably necessary to register domain names or 
server: modify existing registrations; the Data in VeriSign Global Registry 
server: Services' ("VeriSign") Whois database is provided by VeriSign for 
server: information purposes only, and to assist persons in obtaining information 
server: about or related to a domain name registration record. VeriSign does not 
server: guarantee its accuracy. By submitting a Whois query, you agree to abide 
server: by the following terms of use: You agree that you may use this Data only 
server: for lawful purposes and that under no circumstances will you use this Data 
server: to: (1) allow, enable, or otherwise support the transmission of mass 
server: unsolicited, commercial advertising or solicitations via e-mail, telephone, 
server: or facsimile; or (2) enable high volume, automated, electronic processes 
server: that apply to VeriSign (or its computer systems). The compilation, 
server: repackaging, dissemination or other use of this Data is expressly 
server: prohibited without the prior written consent of VeriSign. You agree not to 
server: use electronic processes that are automated and high-volume to access or 
server: query the Whois database except as reasonably necessary to register 
server: domain names or modify existing registrations. VeriSign reserves the right 
server: to restrict your access to the Whois database in its sole discretion to ensure 
server: operational stability.  VeriSign may restrict or terminate your access to the 
server: Whois database for failure to abide by these terms of use. VeriSign 
server: reserves the right to modify these terms at any time. 
server: The Registry database contains ONLY .COM, .NET, .EDU domains and
server: Registrars.

As you can see, all you needed to do after connecting to the server was type the search string and press ⏎. The server then returned the information it had, and terminated the connection.