Difference between cname and A record in DNS

CNAME (Canonical Name) and A (Address) records are two types of DNS records used to map domain names to IP addresses or other domain names. Here’s the difference between them:

1. A Record (Address Record):

   • Purpose: Maps a domain name directly to an IP address (either IPv4 or IPv6).
   • Usage Example: If you have a domain example.com and want it to point to a server with IP address 192.0.2.1, you'd use an A record.
   • How It Works: When someone visits example.com, the DNS resolver looks up the A record to find the IP address and directs the request to that server.
   • Example Record:

     example.com.    IN    A    192.0.2.1
     

2. CNAME Record (Canonical Name Record):

   • Purpose: Maps one domain name to another domain name (an alias).
   • Usage Example: If you want www.example.com to point to example.com without needing to change the IP address for both, you'd use a CNAME.
   • How It Works: When someone visits www.example.com, the DNS resolver first looks up the CNAME record, which tells it to refer to example.com. Then it finds the IP address for example.com through its A record.
   • Example Record:

     www.example.com.    IN    CNAME    example.com.
     

Key Differences:

• Direct vs Indirect Mapping:

  • A records point directly to an IP address.
  • CNAME records point to another domain name, which then resolves to an IP address.

• Chaining of Domain Names:

  • A records cannot point to another domain name.
  • CNAME records create an alias for another domain name.

• Use Case:

  • Use an A record when you have a domain that you want to point to a specific IP.
  • Use a CNAME when you want multiple domain names to point to the same domain, simplifying DNS management.