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Accepted
Arseni Mourzenko
Asked: 2020-01-02 07:39:16 +0800 CST

Can I use “@” as a canonical name in the CNAME resource record?

  • 772

I have a CNAME RR which points to the same domain as defined in the $ORIGIN:

$TTL 604800
$ORIGIN example.com.
...
    IN A     10.0.0.5
www IN CNAME example.com.

Is it mandatory to specify the FQDN in the canonical name here, or can I use instead the following forms?

www IN CNAME @

or:

www IN CNAME

I checked Pro DNS and BIND 10 by Ron Aitchison, as well as the CNAME record article on Wikipedia, and none explain if this is allowed or not (and both sources put a FQDN in the examples).

bind

1 Answers

  1. Best Answer

    As Håkan remarks in a comment, the @ and $ORIGIN directives are part of the original zone file format (cf. Bind 9 manual and RFC 1035).

    The directives:

    www IN CNAME @

    and

    www IN CNAME example.com.

    are equivalent, assuming $ORIGIN example.com..

    Since the $ORIGIN directive is also optional in Bind 9, you can create a zone file without mentioning your FQDN even once.

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