System that translates human-readable domain names, such as www.example.com, into IP addresses, which are used by computers to identify each other on the internet.

The Domain Name System (DNS) is a distributed, hierarchical naming architecture that resolves human-readable domain names into IP addresses and other resource records by recursively querying authoritative name servers via UDP/TCP over port 53, enabling scalable, fault-tolerant hostname-to-resource mapping across the internet.

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Index

Name System

Structure of the Namespace

• Syntax of names: Defines how names are written and parsed. This includes supported characters, delimiters (e.g., dots in DNS), and extensibility mechanisms.
• Types of records: Specifies what kinds of data are associated with names (e.g., A, MX, TXT in DNS).
• Possible structures:
  • Flat: All names exist at the same level (e.g., early host files).
  • Hierarchical: Names are organized in a tree structure (e.g., DNS).
  • Other: Hybrid or distributed structures.

Administrative Structure

• Record storage: Determines which servers are responsible for storing name records.
• Lookup mechanism: Describes how queries are routed to the appropriate servers.
• Structure possibilities:
  • Flat: Centralized or replicated database.
  • Hierarchical: Delegation of authority across levels (e.g., root → TLD → domain).

Authoritative Structure

• Authority and binding: Who is allowed to assign names and update bindings.
• Delegation: How authority is passed down or distributed (e.g., parent domain delegates to child).
• Design principle: Ideally, the authoritative structure should mirror the administrative structure for clarity and coherence.