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Re: Weird DNS issues for domains
- From: Todd Vierling
- Date: Thu Sep 29 13:31:06 2005
On Thu, 29 Sep 2005, John Dupuy wrote:
> If you are talking about strictly http, then you are probably right. If you
> are hosting any email, then this isn't the case. A live DNS but dead mail
> server will cause your mail to queue up for a later resend on the originating
> mail servers. A dead DNS will cause the mail to bounce as undeliverable.
If a mail server is bouncing immediately on a DNS SERVFAIL (which is what
you'll get when a remote DNS server is down), then that mail server is badly
broken and will break quite a bit during tier1 failure situations.
Failure to resolve != resolves to NXDOMAIN/empty. A failure to resolve
(SERVFAIL) should result in the same queueing behavior that the remote SMTP
server uses for failure to establish a TCP connection.
-- Todd Vierling <email@example.com> <firstname.lastname@example.org> <email@example.com>