This article was previously published under Q171789
When you run Nslookup from a command prompt on your Microsoft WindowsNT 4.0 Domain Name Service (DNS) server, you receive the following errormessage:
**** Can't find server name for address x.x.x.x: Non-existent domain **** Default server is not available Default Server: UnKnown Address: x.x.x.x
Where x.x.x.x is the IP address of your DNS server.
NOTE: This problem may occur with other applications as well.
There is a missing or mis-configured PTR record for your DNS server in yourreverse lookup zone. The DNS Manager does not automatically create a PTRrecord for your DNS server, even though it may automatically create an "A"record in your forward zone.
To resolve this problem, perform the following steps:
From DNS Manager, open your forward zone.
Right-click on the "A" record for your DNS server, and then click Delete Record.
Click Yes to confirm the deletion of the "A" record.
Right-click on the forward zone, and then click New Host.
Type the host name of your DNS server and the IP address.
Select the Create Associated PTR Record check box.
Click Add Host, and then click Done.
If you receive an error when you click Add Host, then you may be having aproblem with your reverse lookup zone.
For additional information, please see the following articles in theMicrosoft Knowledge Base:
166753 Microsoft DNS Server Reverse Lookup Error Adding Host Record
162842 DNS with "WINS Reverse Lookup" Fails with Multiple IP Addresses
Microsoft has confirmed this to be a problem in Windows NT version 4.0. Weare researching this problem and will post new information here in theMicrosoft Knowledge Base as it becomes available.
You can view the properties of an "A" record by right-clicking on it and thenclicking Properties. When the above problem is encountered, the "A" recordproperties will have a check in Update Associated PTR Record. This seems toindicate that the PTR record has been created and is active, however, it isnot true.
The reverse lookup zone is a database file that is used to allow a client,or resolver, to provide an IP address and request a matching host name.This file contains an SOA record and NS records similar to other DNSdatabase zone files. It also contains pointer records.
This DNS reverse lookup capability is important because some applicationsprovide these capabilities to implement security based on the connectinghost names. Nslookup is one of these utilities.