A DNS lookup returns an IP address or a domain name depending on whether it is a forward or reverse lookup. Thus if you have a domain name you can find out its IP number and if you know the IP address you can look up the corresponding domain name.

Nonetheless, when a DNS lookup is done with a particular intention such as finding out the owner of a website, the process does not end with the return of an IP address or domain name. You will need more specific information such as the name and contact details of the domain holder or the location of the IP address. This is where the WHOIS database comes handy.

The Internet WHOIS system is a database that stores the registration details and contact information of owners of public IP addresses. For generic top-level domains, the ICANN requires the accredited registrars to record and provide public access to the data on registered domain names. This database is accessible by anyone, anytime and holds the following information:

  • name and IP address of the registered domain
  • list of nameservers associated with it
  • the name of the domain registrar
  • the date of registration of the domain
  • the date of expiry of the domain registration
  • the name and contact details of the registered domain name holder
  • the details of the technical contact
  • the details of the administrative contact

According to the ICANN, there are five Regional Internet Registries (RIRs) that ensure a fair distribution and management of the Internet number resources. These are ARIN, LACNIC, AfriNIC, RIPE NCC and APNIC. These organizations along with many other websites offer WHOIS lookup services. Usually, a domain registrar will have this lookup service on their site to facilitate the domain registration process. A WHOIS search will easily establish if a domain name is available or when an already taken name expires. The contact details will be useful for people interested in buying registered domain names.

Sometimes for security reasons, you might not want your name and contact details to be made public through the WHOIS database. In such cases, you can opt to hide your details. Often domain registrars offer private domain registration at an extra cost. When you opt for private registration, the registrar replaces your contact information on the WHOIS database with alternate contact information which might include the registrar’s details. Using a proxy server can also effectively mask your identity on the Internet. Such measures are usually employed nowadays, to protect domain holders from spammers, hackers, identity thefts and the likes.