• Domain Name Service

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  2. Domain Name Service
  3. User Guide
  4. Overview
  5. Basic Concepts
  6. Domain Name Levels

Domain Name Levels

Domain names are classified into the following levels:

  • Root domain: . (a dot)
  • Top-level domain: for example, .com.net.org, and .cn
  • Second-level domain: subdomain names of the top-level domain names, such as example.comexample.net, and example.org
  • Third-level domain: subdomain names of the second-level domain names, such as abc.example.comabc.example.net, and abc.example.org
  • The next level domain names are similarly expanded by adding prefixes on the left of the previous-level domain names.
    • A domain name is segmented using dots (.).
    • Each label can contain letters, digits, and hyphens (-) and cannot start or end with a hyphen.
    • A domain name label cannot exceed 63 characters.
    • A domain name is not case-sensitive and does not exceed 254 characters, including the dot added at the end by default.