"no data known" vrs "host not found"
admjcd
admjcd at VOLPE.DOT.GOV
Tue Mar 26 17:27:03 UTC 2002
Yes, its sendmail and this is from a message header: (8.8.8/1.1.22.3/21May99-0417PM) that says the version right?
There are Two DNS servers with one set up as a backup. I am actually the mail person and run our Exchange servers but our DNS peolple handle the sendmail server. They do not like that I am pressing this issue, but the customers call me when the mail fails.
Also I did some research on "negative Caching" and found this :
http://www.faqs.org/rfcs/rfc2308.html
"Negative responses without SOA records SHOULD NOT be cached as there
is no way to prevent the negative responses looping forever between a
pair of servers even with a short TTL.
Despite the DNS forming a tree of servers, with various mis-
configurations it is possible to form a loop in the query graph, e.g.
two servers listing each other as forwarders, various lame server
configurations. Without a TTL count down a cache negative response
when received by the next server would have its TTL reset. This
negative indication could then live forever circulating between the
servers involved."
-----Original Message-----
From: Barry Finkel [mailto:b19141 at achilles.ctd.anl.gov]
Sent: Monday, March 25, 2002 12:49 PM
To: bind-users at isc.org
Cc: admjcd at volpe.dot.gov
Subject: Re: "no data known" vrs "host not found"
In article <a7g931$kmf at pub3.rc.vix.com>, admjcd <admjcd at VOLPE.DOT.GOV> wrote:
>>When ever we send mail we get back these NDRs when ever the domain is
>>not correct. Sometimes we get them when the domain is correct. Both
>>types are "host unknown". One says "no data known" and the others
>>say "host not found" . What is the difference between these two and
>>why should we get the "no data known" intermittenly message when the
>>domain does exist?
Barry Margolin <barmar at genuity.net> replied:
>Something very weird is going on with the army.mil entries that result
>in "no data known" messages. They have MX records, but if you perform
>an ANY query (as sendmail does), the MX record appears in the Authority
>section instead of the Answer section. And its TTL decreases on each
>query, implying that the MX record is in the cache, not the
>authoritative data for the zone. You should probably let the Army
>hostmaster know that there's a problem with their server.
I have seen this problem with the Army's DNS for a long time (Dec 2000). I even posted the problem here May 30, 2001. I have not gotten a reply from army.mil since my initial queries in 2000, and obviously the problem has not been corrected.
----------------------------------------------------------------------
Barry S. Finkel
Electronics and Computing Technologies Division
Argonne National Laboratory Phone: +1 (630) 252-7277
9700 South Cass Avenue Facsimile:+1 (630) 252-4601
Building 222, Room D209 Internet: BSFinkel at anl.gov
Argonne, IL 60439-4828 IBMMAIL: I1004994
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