nanog mailing list archives
Re: Weird DNS issues for domains
From: Crist Clark <crist.clark () globalstar com>
Date: Thu, 29 Sep 2005 11:00:16 -0700
Todd Vierling wrote:
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.
The problem I've seen is when an SMTP server does not accept emails which have non-resolvable MAIL FROM domain. When the sender is a dumb SMTP client, not an MTA, this can cause problems. (I noticed this happen to a high traffic customer who had both of their DNS servers in the same /24 located in Slidell, LA. Needless to say, they were down for more than a few hours when Katrina rolled through.) -- Crist J. Clark crist.clark () globalstar com Globalstar Communications (408) 933-4387
Current thread:
- Weird DNS issues for domains Matthew Crocker (Sep 29)
- Re: Weird DNS issues for domains Jason Frisvold (Sep 29)
- Re: Weird DNS issues for domains Robert E . Seastrom (Sep 29)
- Re: Weird DNS issues for domains Matthew Crocker (Sep 29)
- Re: Weird DNS issues for domains John Dupuy (Sep 29)
- Re: Weird DNS issues for domains Petri Helenius (Sep 29)
- Re: Weird DNS issues for domains Randy Bush (Sep 29)
- Re: Weird DNS issues for domains Todd Vierling (Sep 29)
- Re: Weird DNS issues for domains Crist Clark (Sep 29)
- Re: Weird DNS issues for domains Peter (Sep 30)
- Re: Weird DNS issues for domains Crist Clark (Sep 30)
- Re: Weird DNS issues for domains Matthew Crocker (Sep 29)
- Re: Weird DNS issues for domains John Dupuy (Sep 29)
- Re: Weird DNS issues for domains Randy Bush (Sep 29)
- Re: Weird DNS issues for domains Todd Vierling (Sep 29)
- Re: Weird DNS issues for domains Bjørn Mork (Sep 29)
- Re: Weird DNS issues for domains Robert E . Seastrom (Sep 29)
- Re: Weird DNS issues for domains Mark Andrews (Sep 29)
- Re: off-list Re: Weird DNS issues for domains Edward Lewis (Sep 29)