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'.


-- 
Per Jessen, Zürich (28.8°C)
http://www.dns24.ch/ - your free DNS host, made in Switzerland.



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