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 <tv@duh.org> <tv@pobox.com> <todd@vierling.name>