On Fri, 31 December 1999, jlewis@lewis.org wrote:
I guess our customers aren't that silly. I did notice some big sites down though. I tried to check a price with Tech Data earlier this evening and found that www.techdata.com didn't exist. Traceroute to their nameserver(s)
techdata.com. 2D IN NS NS1.techdata.com. techdata.com. 2D IN NS NS2.techdata.com. NS1.techdata.com. 2D IN A 169.153.202.40 NS2.techdata.com. 2D IN A 169.153.202.41
ends in a CW routing loop suggesting TD shut off their connection for the evening.
Putting your only name servers on the same subnet (unless Tech Data has VERY small subnets) isn't very smart no matter what day it is. Too many things can take down your one network. Instead of queueing mail, many mail programs will generate permanent errors and immediate bounces. Gun, Foot, Self.
On 1 Jan 2000, Sean Donelan wrote:
Putting your only name servers on the same subnet (unless Tech Data has VERY small subnets) isn't very smart no matter what day it is. Too many things can take down your one network. Instead of queueing mail, many mail programs will generate permanent errors and immediate bounces.
What programs are that? I was under the illusion that everybody mimicked sendmails behaviour in that if you cannot get an authoritative answer, queue it whatever everything else (basically). But then again, why should they work properly? :/ -- Mikael Abrahamsson email: swmike@swm.pp.se Fax/voicemail: +46 (0) 8-59825186
[ On Saturday, January 1, 2000 at 15:37:34 (+0100), Mikael Abrahamsson wrote: ]
Subject: Re: Customers down?
What programs are that? I was under the illusion that everybody mimicked sendmails behaviour in that if you cannot get an authoritative answer, queue it whatever everything else (basically).
I know for certain that Postfix and Smail will immediately bounce a message when the domain is authoritatively non-existant. I'd be very surprised and dismayed if sendmail and all other true SMTP mailers did not do exactly the same thing. If you're lucky/smart enough you can make your main e-mail domain be the same domain name as one of your registered nameservers and then at least RFC-974 will have mailers queue outgoing mail to your domain, but that's about the only way to prevent your mail from bouncing if all of your authoritative nameservers disappear long enough from the net. This kind of trick limits you in other ways though so it won't be ideal for everyone, and of course if you have more "main" e-mail domains than registered nameservers (of your own) then you'll be hosed anyway. -- Greg A. Woods +1 416 218-0098 VE3TCP <gwoods@acm.org> <robohack!woods> Planix, Inc. <woods@planix.com>; Secrets of the Weird <woods@weird.com>
"Greg A. Woods" wrote:
I know for certain that Postfix and Smail will immediately bounce a message when the domain is authoritatively non-existant. I'd be very surprised and dismayed if sendmail and all other true SMTP mailers did not do exactly the same thing.
Sendmail most definitely does not, instead treating the error as a transient error, issuing an SMTP error code in the 400 series, and continuing to try to send the mail for up to five days (the default), or whatever the mail server admin configured for that particular server. I think I like it better that way. Just because both nameservers are temporarily down doesn't mean the domain doesn't exist. :P -- North Shore Technologies Corporation - Steven J. Sobol, President & Head Geek 815 Superior Avenue #610, Cleveland, Ohio 44114, USA Phone +1 888.480.4NET sjsobol@NorthShoreTechnologies.net http://NorthShoreTechnologies.net Owned and loved by the dogs of Jaymist Chinese Shar-Pei, Montville, Ohio :) Alcohol and calculus don't mix.. Never drink and derive.
On Sat, Jan 01, 2000 at 03:07:43PM -0500, Steve Sobol wrote:
I know for certain that Postfix and Smail will immediately bounce a message when the domain is authoritatively non-existant. I'd be very surprised and dismayed if sendmail and all other true SMTP mailers did not do exactly the same thing.
I beg to differ.
Sendmail most definitely does not, instead treating the error as a transient error, issuing an SMTP error code in the 400 series, and continuing to try to send the mail for up to five days (the default), or whatever the mail server admin configured for that particular server.
Yep.
I think I like it better that way. Just because both nameservers are temporarily down doesn't mean the domain doesn't exist. :P
Or, worse, there's a glitch in the root servers or the registry maintaining the authoritative data. Or everything's fine on that side and the mail server receiving the message has been temporarily disconnect from the 'global truth'. Better to queue temporarily and treat it as a transient failure than to drop. That's almost always the best approach for loosely coupled systems, IMHO. Cheers, Chris -- Christian Kuhtz Architecture, BellSouth.net <ck@arch.bellsouth.net> -wk, <ck@gnu.org> -hm Atlanta, GA "Speaking for myself only."
participants (5)
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Christian Kuhtz -
Mikael Abrahamsson -
Sean Donelan -
Steve Sobol -
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