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What is Authority in DNS?

Published in DNS Concepts 3 mins read

In the context of the Domain Name System (DNS), authority refers to the designated server or set of servers that hold the definitive, official records for a specific domain name (like example.com). These servers are known as authoritative DNS servers.

Think of it like a library's card catalog for a specific subject – it's the official source for finding books related to that subject. In DNS, the authoritative server is the single source of truth for a domain's records.

The Role of the Authoritative DNS Server

An authoritative DNS server is critical to how the internet works. As the reference states, the authoritative DNS server is the final holder of the IP of the domain you are looking for. When you type a domain name into your browser, the DNS resolution process begins:

  1. A query is sent, often starting with your Internet Service Provider (ISP).
  2. Your ISP typically has a recursive DNS server. This server tries to find the answer, potentially using information cached from previous queries.
  3. If the recursive server doesn't have the answer, it queries other servers (like the root and Top-Level Domain servers) until it is referred to the correct authoritative server for the specific domain.
  4. The authoritative server then provides the official IP address (or other requested DNS records) for that domain.

This final response from the authoritative server is considered the authoritative answer because it comes directly from the source responsible for maintaining the domain's DNS records.

What Information Does an Authoritative Server Hold?

An authoritative server holds various types of DNS records that define how a domain functions. Some common examples include:

  • A Records: Maps a domain name to an IPv4 address (e.g., example.com to 93.184.216.34).
  • AAAA Records: Maps a domain name to an IPv6 address.
  • CNAME Records: Creates an alias from one domain name to another (e.g., www.example.com pointing to example.com).
  • MX Records: Specifies the mail servers responsible for receiving email on behalf of a domain.
  • TXT Records: Stores text information, often used for verification purposes or SPF/DKIM records for email security.
  • NS Records: Lists the authoritative name servers for a domain, delegating authority to those servers.

The authoritative server provides these records directly, ensuring that users are directed to the correct resources associated with the domain.

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