Date: Mon, 20 May 2002 11:48:23 -0700 From: "Crist J. Clark" <crist.clark@attbi.com> To: Damon Anton Permezel <dap@damon.com> Cc: Peter Pentchev <roam@ringlet.net>, freebsd-qa@FreeBSD.ORG, freebsd-hackers@FreeBSD.ORG Subject: Re: 4.6-* sendmail misfeatures Message-ID: <20020520114823.D1468@blossom.cjclark.org> In-Reply-To: <20020520122558.F962@damon.com>; from dap@damon.com on Mon, May 20, 2002 at 12:25:58PM -0500 References: <20020520105154.E962@damon.com> <20020520191546.D349@straylight.oblivion.bg> <20020520122558.F962@damon.com>
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On Mon, May 20, 2002 at 12:25:58PM -0500, Damon Anton Permezel wrote: > It is not a matter of a timeout. Correct. The NS is actually reporting a transient error in response to AAAA queries. > The "A ?" come back fine. > `dig' and 'nslookup' both resolve the name -- there is no timeout. > `ping' works, for example. > > Because sendmail "correctly" (aka: anal-retentively) adheres to a > protocol, it flags this as an error, Not sure what's so anal-retentive. The NS tells sendmail(8) there is an error and sendmail(8) believes it. > and doesn't attempt to try the > "A ?" query. This means that the outgoing mail sits in the queue forever. > > This is not a particularly useful default behavior. > > I have no control over austinenergy.com's DNS. It has nothing to do > with my ISP. I am my own ISP, which is why I spent some time looking > into this failure, to determine if it was a problem on my end. It is, > because I installed a broken sendmail. > > The success of the internet has often been attributed in part to the > philosophy stated in RFC 791. I quote: > > "The implementation of a protocol must be robust. Each > implementation must expect to interoperate with others created > by different individuals. .... > In general, an implementation must be conservative in its sending > behavior, and liberal in its receiving behavior." Too bad the people who wrote these broken DNS servers didn't follow the rule. > Burying a "we are correct" manifesto in some README and enforcing > a default "correct" behavior results in breaking email connectivity. > > It would be better to, perhaps, default to working, which I would > prefer over it being silently, secretly and smugly "correct". > If there really is a need to convert the world, syslog warning > entries might be a less unfriendly way to alert the unwashed masses > of the egregious violations of "correctness". The issue is that the server is reporting a _transient_ failure. That is, it's telling us that if we wait and try again later, we might get a correct response. How do we know if it is a permanently broken server or one that really is having a transient problem that will be fixed soon? See 5.2.3 of RFC 1034. Funny thing is that austinenergy.com seems to have one NS that deals with AAAA queries in an OK-way and one that doesn't. -- Crist J. Clark | cjclark@alum.mit.edu | cjclark@jhu.edu http://people.freebsd.org/~cjc/ | cjc@freebsd.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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