12 Feb
2012
12 Feb
'12
3:33 p.m.
Hello,
On Sun, Feb 12, 2012 at 02:42, Andy Bennett <andyjpb(a)ashurst.eu.org> wrote:
No, the lack of response from all authoritative nameservers for a
domain is not treated the same way as a "NXDOMAIN" response from one
of them. The former results in the resolver returning a temporary
error.
Regards,
Daniel
For SMTP
specifically, the current specification is also quite clear
(RFC 5321, section 5.1):
"The lookup first attempts to locate an MX record associated with
the name. If a CNAME record is found, the resulting name is processed
as if it were the initial name. If a non-existent domain error is
returned, this situation MUST be reported as an error. If a temporary
error is returned, the message MUST be queued and retried later (see
Section 4.5.4.1)."
Quite... and lack of any NS servers tends to be treated as a
non-existent domain.