What is an A record used for in DNS ?

What is a DNS A Record ? – An A-record (Address Record) in the Domain Name System (DNS) is a type of record that maps a domain name to its corresponding IPv4 address.

It serves as the fundamental link between a human-readable domain name (e.g., example.com) and a numerical IP address (e.g., 192.0.2.1), which is necessary for computers to locate and connect to servers.

Key Features of an A-Record:

  1. Domain Name to IP Mapping: It translates the domain name into a specific IPv4 address.
    • Example: example.com. 3600 IN A 192.0.2.1
      • example.com.: The domain name.
      • 3600: Time-to-live (TTL), the duration in seconds that the record is cached.
      • A: Specifies it’s an A-record.
      • 192.0.2.1: The IPv4 address associated with the domain.
  2. One-to-Many Relationships: Multiple A-records can exist for a single domain to provide load balancing or redundancy by pointing to different servers.
  3. IPv4-Specific: A-records are used for IPv4 addresses. For IPv6, the equivalent record is an AAAA-record.
  4. Resolution Process:
    • When a user enters a domain name in their browser, the DNS system retrieves the A-record to find the corresponding IP address and connects the user to the server hosting the website.

Example Use Cases:

  • Linking a website’s domain name to its web server’s IP address.
  • Mapping subdomains (e.g., www.example.com or api.example.com) to different servers.

If the server’s IP address changes, the A-record must be updated to maintain connectivity.