On 26 Jul 2018, at 11:23, Alex wrote:
I have a postfix-3.3.1 running on a fedora28 system and frequently see
warnings such as these in my logs:
Jul 26 10:42:09 mail03 postfix/dnsblog[3949]: warning: dnsblog_query:
lookup error for DNS query 51.225.249.24.b.barracudacentral.org: Host
or domain name not found. Name service error for
name=51.225.249.24.b.barracudacentral.org type=A: Host not found, try
again
This is a potentially misleading error message due to a postfix/resolver
quirk. It DOES NOT mean that "51.225.249.24.b.barracudacentral.org"
resulted in a NXDOMAIN, it means that an A record for a name server for
the parent domain could not be found. A completed resolution with a
NXDOMAIN result is silent.
Shouldn't this DNSBL be responding with a "not listed" code instead of
just NXDOMAIN?
With the caveat that this is NOT what is causing that logged error: No.
NXDOMAIN is the answer a DNSBL is supposed to give when an address is
not listed, so there is no other possible correct response for a
non-listing.
