[T] DNS CNAME and A/AAAA Records

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Janis König

Letztes Update

16.12.2025

The Domain Name System (DNS) uses different types of records for name resolution, including MX (mail), TXT (various). The A and AAAA records are used to match a domain to an IPv4 and IPv6 address, respectively:

Type	Entry	Pointer
A	example.org	192.0.2.42
AAAA	example.org	2001:db8:1234::42
A	vpn.example.org	192.0.2.137

In this case, the domain example.org will be resolved to a different IP than vpn.example.org , and the latter only being reachable through IPv4.

In addition, there exist CNAME records which allow to point a domain to another domain, triggering a an A/AAAA record lookup only through indirection:

Type	Entry	Pointer
CNAME	www.example.org	example.org

Here, the www-subdomain www.example.org should point to whatever the second level domain should point to.

[T] DNS CNAME and A/AAAA Records

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