DNS Lookup, Reverse DNS Lookup, Domain Configuration Check and IP Address Calculators

What is a Domain Name

A domain name or internet name is the user friendly name that is used to locate internet (or network) resources. Although devices on a network can be accessed by directly using their IP address, IP addresses are numerical identifiers that most people find hard to remember. If an IP address changes (for example, when a website is moved to a new server or new ISP), you would have a new IP address to remember. With domain names, the name the user needs to remember is abstracted from the IP address.

With a high availability website, which has multiple web servers, the domain name can be configured to resolve to one of multiple IP addresses, therefore giving a level of load-balancing which would be certainly harder if users directly used the IP address.

Domain Hierarchy

Domain names follow a hierarchal structure. Each part of the hierarchy is separated by a dot (.). At the top of the hierarchy are the Top Level Domain (TLD) names. Examples of TLD's are .com, .org, .net and the 2 letter country codes. Some TLD's allow you to register subdomains directly under the TLD, for example .com, .org and .net. Other TLD's only allow third level registrations, for example .uk and .au.

When a domain is registered, control of that domain name is then delegated to the owner of the registration.

Domain Registration

Domain names are registered with a domain name registrar. The registrar will create a 'whois' record for the domain name and create nameserver entries for the domain. The whois record contains contact information for the registrant of the domain. The nameserver entries specify the DNS servers for the domain, which allow people to find your website or email servers. For more information on DNS, refer to the What is DNS article on this website.

A domain name can be divided into subdomains. Control of a subdomain can be managed on the same DNS servers as the main domain, or control of these subdomains can be delegated to other people.

An example of a domain name is example.com. With this domain name, example.com is a subdomain of the .com TLD. The owner of this domain name can then create subdomains of example.com.