Good Afternoon,
My senior tech and I have been having a squabble over PTR, Hostnames and
reverse mapping.
If you have a client connect from 1.2.3.4 and perform a host name lookup
on that, so you get back host.example.com, would it impact on mail if a
forward query for host.example.com returned multiple A records, say
1.2.3.4 & 5.6.7.8 alternating between the top of the result sets in a
round robin?
I ask because we've seen an slightly odd pattern to some deferrals with
a host where this happens and wonder if they may be using:
reject_unknown_client_hostname feature, which requires not only
that the address->name and name->address mappings exist, but
also that the two mappings reproduce the client IP address.
The unknown_client_reject_code parameter specifies the response
code for rejected requests (default: 450). The reply is always
450 in case the address->name lookup failed due to a temporary
problem.
Sam
