North American Network Operators Group

Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical

RE: mail does bounce (was: Customers down?)

  • From: Owen DeLong
  • Date: Sun Jan 02 15:23:58 2000

> > > I think I like it better that way. Just because both nameservers are
> > > temporarily down doesn't mean the domain doesn't exist. :P
> > 
> > Seems to me you're talking past one another. If all nameservers for a
> > domain are down there *is* no nameserver which can say that the domain
> > is authoritatively non-existent. (OK, you could get a negative caching
> > answer from one of the authoritative servers on the level above, but
> > that's a different issue...)
> > 
> > I agree with Greg Woods - if a domain is authoritatively non-existent,
> > I'd expect a sane mailer to bounce the message.
> I'm glad that you don't write code, especially sendmail code.
I'm hoping that some clarification of terms will kill this thread...

There is a difference between the following terms:

Authoritatively Non-existant domain:
	A domain for which the servers authoritative for the parent
	zone report that the domain does not exist.

Unreachable Authoritative Servers:
	A domain which exists and posesses a delegation in it's
	parent servers, but which authoritative servers are
	currently not reachable.

The former is regarded as a permanent error and mail is immediately
bounced by every mailer I know of.

The latter is a transient error and is treated as such by sendmail.
I would hope it would be treated as such by other mailers.