Microsoft Knowledge Base

• Microsoft Windows NT Workstation versions 3.5, 3.51, and 4.0
• Microsoft Windows NT Server versions 3.5, 3.51, and 4.0
• Microsoft Windows 95

SYMPTOMS

When you use Nslookup from a command prompt it produces the following message:

   Can't find server name for address "DNS IP address": Non-existent Domain
   Default servers are not available
   Default Server: Unknown

CAUSE

This error occurs because Nslookup is attempting to do a reverse lookup to resolve the host name of the default DNS server. When Nslookup initializes, it gets the IP address of the first DNS server listed in the TCP/IP properties of the Network Control Panel.

Once an IP address is obtained, Nslookup does a reverse lookup query to your DNS server to determine the server name associated with the IP address it obtained earlier. If a reverse lookup zone is not present, or there is not a valid PTR record for the DNS server in an existing reverse lookup zone, the aforementioned message will appear when attempting to use Nslookup. This is an informational error message and Nslookup will still function properly.

RESOLUTION

Create a valid reverse lookup zone and add a PTR record for the DNS server using DNS manager.

For additional information, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q162842
   TITLE     : DNS with "WINS Reverse Lookup" fails with multiple
               IP addresses.