Re: [swinog] PTR records with CNAME ?

On 2018-05-30 16:44, Per Jessen wrote:

According to RFC1034 and 2181, a PTR record using a CNAME is not permitted. I believe this to still be correct, postfix certainly doesn't work with a CNAME when it does a reverse lookup.

Postfix certainly does as:

$ dig +short 50.131.144.213.in-addr.arpa. ptr 50.63-28.131.144.213.in-addr.arpa. citadel.ch.unfix.org.

would otherwise not work.... and that trick of CNAME'ing in-addr.arpa space is used a lot by ISPs to delegate space (as per the above example where init7 forwards them to my nameservers).

There is also a nice RFC on that:

https://www.ietf.org/rfc/rfc2317.txt

Greets, Jeroen