What is DNS?

• Domain Name System
• DNS Provide simple way to communicate devices on the internet without remembering their IP addresses.

Domain Hierarchy

TLD(Top-Level Domain)

• It is the most right hand part of a domain name.
• for example .com in tryhackme.com.
• there are two types of TLD:

  • gTLD (Generic Top Level)

    eg: .com, .org, .edu

  • ccTLD (Country Code Top Level)

    eg: .in , .co.uk , .ca

Second Level Domain

• taking tryhackme.com as an example .com part is the TLD and tryhackme is the second level domain.
• Second Level domain is limited to 63 characters.

Subdomains

• sits on the left side of domain.

• in admin.tryhackme.com the admin part is the subdomain.

• there is no limit to subdomain that u can make for a domain.

• same creation restriction as second level domain (63 characters.)

• The Maximum length of a domain should be less than 253.