What is Domain Name System (DNS)

DNS name is a human-friendly name of a website that resolves an IP address with a domain name. When you type a domain name in a search bar such as example.com it resolves with the number known as IP address. You may say it’s like your phone book where you save your contact name with their phone number.

DNS uses port 53 for both TCP and UDP. It uses UDP for Zone transfer and TCP when the information gets larger than 512 bytes.

DNS Resolution methods

There are two ways to resolve domain name with the IP address (1) Forward lookup where you type an Internet domain name to find an IP address. (2) Reverse lookup where you type an IP address to find a domain name.

DNS Records

DNS records work as instructions for the DNS server so it knows which domain names with each IP address is associated with. It is also known as zone transfer.

A and AAA – this refers to the actual IP address that’s associated with the domain. ‘A’ is for IPv4 and ‘AAA’ is for IPv6.

NS (Name Server) – it is referred to as a hostname.

MX – it is a mail record that directs mail to an email server

CNAME (canonical name) – it is an alias for the real domain which transfers one domain/subdomain to another domain.