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Re: Weird DNS issues for domains
- From: John Dupuy
- Date: Thu Sep 29 14:13:21 2005
I'll defer to you on this. Clearly a failure to resolve is
not the same thing as a NXDOMAIN RCODE.
And yet, personal experience has show that the failure of all a
customer's DNS servers for a domain does cause swifter mail bouncing than
would occur otherwise. I do not know if it was due to the other providers
having broken MTAs or broken DNS servers/resolvers... Or maybe they were
all flukes. I now wish I had investigated them more thoroughly for the
few times I've seen it.
At 12:29 PM 9/29/2005, Todd Vierling wrote:
On Thu, 29 Sep 2005, John Dupuy
> If you are talking about strictly http, then you are probably right.
> are hosting any email, then this isn't the case. A live DNS but dead
> server will cause your mail to queue up for a later resend on the
> mail servers. A dead DNS will cause the mail to bounce as
If a mail server is bouncing immediately on a DNS SERVFAIL (which is
you'll get when a remote DNS server is down), then that mail server is
broken and will break quite a bit during tier1 failure
Failure to resolve != resolves to NXDOMAIN/empty. A failure to
(SERVFAIL) should result in the same queueing behavior that the remote
server uses for failure to establish a TCP connection.
-- Todd Vierling <email@example.com> <firstname.lastname@example.org>