Domain Name System (DNS)

What is Domain Name System (DNS)

The Domain Name System (DNS) is the phone book of the Internet - it links host names to IP addresses. In this manner, users can easily use a domain name.

When you type in a domain name into your web browser, your computer will check if it knows to which IP address this request should go. If it doesn't know, it will ask it's DNS servers. These DNS servers are set in your network settings and are provided by default by your Internet service provider. The servers will check if they know the correct IP address, and if they don't, they will go through the following steps to determine the correct IP address:

For more information about how DNS works, please refer to the following tutorials by the Dutch SIDN organisation (responsible for the .nl top level domain):

Authoritative & Non-authoritative DNS name servers

DNS name servers are commonly split into two categories:

  • Authoritative name servers
  • Non-authoritative name servers

The difference between these two is that the authoritative name server holds the record for a domain, and the non-authoritative name server does not. Instead, it just asks other name servers for their records.

Type Description
Authoritative This type of name server holds the record for a domain. It decides which records are being used.
Non-authoritative This is also known as a caching name server. It provides answer to questions to clients. So your computer might ask this type of server for the IP address of www.leaseweb.com. The caching name server then asks the name server for .com where leaseweb.com it's name server is. It gets a reply, and then asks the name servers of www.leaseweb.com. The image below explains the inner working of the system