On 2018-05-30 17:35, Per Jessen wrote:
Jeroen Massar wrote:
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
Okay, thanks for clarifying that - I was wondering. I don't why my postfixes come up with host name 'unknown'.
Where does postfix say 'unknown'? In the prepended "Received: from ..." header? in logs?
Can be many reasons why it does not trust the originally provided data, especially as HELO/EHLO can be spoofed. Also depends on the resolver etc etc, many factors ;)
Greets, Jeroen