Solved

DNS Error

Posted on 2001-06-07
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Last Modified: 2013-12-23
I'm having a problem configuring Microsoft DNS.  Everything seems to be working for resolving server names, but when I do a lookup on the domain, I get.

C:\>nslookup mydomain.com
Server:  dnsserver.mydomain.com
Address:  192.168.0.10

*** dnsserver.mydomain.com can't find mydomain.com: Non-existent domain


Other lookups are working ok.....

C:\>nslookup server1.mydomain.com
Server:  dnsserver.mydomain.com
Address:  192.168.0.10

Name:    server1.mydomain.com
Address:  192.168.0.1


C:\>nslookup 192.168.0.2
Server:  dnsserver.mydomain.com
Address:  192.168.0.10

Name:    server2.mydomain.com
Address:  192.168.0.2


Any suggestions??
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Question by:bnewton
12 Comments
 
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by:AvonWyss
ID: 6165291
You have to add an A record in the root (@) of the domain.
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by:andyalder
ID: 6169160
nslookup looks for the PTR record for the IP address of the DNS server it is to query when nslookup starts. If there is no PTR record for the servers IP address in the reverse lookup file you get this error message. Same with every OS. Doesn't matter though, you won't get any problems if you don't bother to fix it.

http://support.microsoft.com/support/kb/articles/Q171/7/89.ASP? should help.
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by:SunBow
ID: 6169759
I think a lot of mailservers still do both lookups, first name, then address (reverse) before transmitting a load (if not cached).
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by:AvonWyss
ID: 6170395
Mailservers first look up the MX record, which is similar to a CNAME record but with a preference. By this, it's possible to have mutliple MX records which should then be processed from the smallest to the largest preference until the SMTP server was reachable. Because of the MX records, it's not necessary to have a root A record for the domain.

andyadler correctly described why this is happening, and just before I described how this can be changed (that is, so that a lookup to the domain without a host will return an IP address).
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by:andyalder
ID: 6170513
AvonWyss, you posted a day before me actually, I was pointing out that the nslookup error message is due to the PTR being missing rather than the A record.

I didn't read the Ms technote I posted until now. Delete the A record and recreate it indeed, why not just create the missing PTR? Technet has such strange ways of doing things although the end result is the same.

I suppose you might have problems sending to some domains if the DNS server was also a mail server because some mail receivers won't accept mail if there is no PTR for the sender (strong anti-spam settings), wouldn't run DNS and Exchange on same box though, too much work for it.
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by:AvonWyss
ID: 6170522
andyalder, PTR records are used for reverse lookups. A records for forward lookups. The NSLOOKUP call mentionned only does a forward lookup, thus I disagree that the error is due to a PTR record missing. But we may have driftes somewhat away from the original question.
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by:andyalder
ID: 6170549
In the microsoft doc I quoted you can see that the A record already exists. They delete the A record and recreate it so that the GUI automatically creates the missing PTR.

A silent query for the PTR is made by nslookup when it starts up so it can display the friendly name of the DNS server it is querying. Well almost every version of nslookup anyway, not my shareware version for win95:

nslookup version 95.02.28. Copyright 1995 John A. Junod
Server: 192.153.156.22

See, it is rude and does not display the friendly name.

www.acmebw.com/askmrdns/archive.php?question=12 but you will find similar docs on all the unix sites as well.

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AvonWyss earned 100 total points
ID: 6170616
andyalder, I do underdtand your comment and agree with the reverse lookup and PTR stuff, but this really doesn't seem to be what bnewton asked in the first place. I understood his question like this:

Why can't he do a lookup of the domain without host part, e.g. just mydomain.com instead of something.mydomain.com - and the answer is, because there is no root A record in the domain mydomain.com... so to do this lookup he would have to add the A record, which is exactly what I wrote. :-)
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by:andyalder
ID: 6171022
Think you are reading too much into "lookup on the domain" since his example of the error message does not involve looking up the domain but just starting the nslookup proggie. maybe I misread the Q.

I assumed that
>>C:\>nslookup mydomain.com
>>Server:  dnsserver.mydomain.com
>>Address:  192.168.0.10
>>
>>*** dnsserver.mydomain.com can't find mydomain.com: Non-existent domain

meant that the A record for the domain was OK since nslookup knows that the DNS server for the domain is called dnsserver.mydomain.com.

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by:andyalder
ID: 6172934
Avon, You're right. I misread.
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Author Comment

by:bnewton
ID: 6176959
Thanks for your help guys, after creating an A record for the domain, it resolves.
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by:AvonWyss
ID: 6176987
You're welcome, bnewton. Thanks for the feedback and points.
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