Name Resolution in Practice - Anatomy of a Domain Name

  • Components of a Domain Name

    • A domain name consists of three main parts:
    • Subdomain: Example: www
    • Domain: Example: Google
    • Top Level Domain (TLD): Example: .com

  • Understanding TLDs

    • The TLD is the last part of the domain name, which indicates the type of organization or geographical area.
    • Common TLDs include:
    • .com
    • .net
    • .edu
    • Specific country TLDs:
    • .de (Germany)
    • .cn (China)
    • Recent expansion of TLDs includes various vanity options like:
    • .museum
    • .pizza

  • Role of ICANN

    • ICANN (Internet Corporation for Assigned Names and Numbers) is responsible for the definition and administration of TLDs.
    • ICANN works closely with IANA (Internet Assigned Numbers Authority) to manage global IP spaces and DNS systems.

  • What is a Domain?

    • The term 'domain' refers specifically to the second part of a domain name (e.g., Google in www.google.com).
    • Domains indicate a transition of control from TLD name servers to authoritative name servers, which are typically managed by independent organizations outside of ICANN.
    • Anyone can register a domain, but it must end with a recognized TLD.

  • Subdomains Explained

    • The subdomain, such as 'www', can be freely chosen and assigned by the owner of the registered domain.
    • Subdomains often denote specific sections within a website.
    • Example of a valid subdomain structure: host.sub.sub.subdomain.domain.com.

  • Fully Qualified Domain Name (FQDN)

    • A fully qualified domain name contains all parts of the domain name and specifies its exact location in the DNS hierarchy.
    • The cost of registering a domain exists, but subdomains can be created at no cost by anyone controlling a domain.
    • The total number of levels in a single FQDN can technically reach up to 127.

  • Character Limitations

    • Individual sections of a domain name (subdomain, domain, TLD) can be up to 63 characters long.
    • The complete FQDN is limited to a total of 255 characters.