DNS Server Search Order Functionality in Windows NT

• Microsoft Windows NT Workstation versions 3.5 and 3.51
• Microsoft Windows NT Server versions 3.5 and 3.51
• Microsoft Windows NT Server version 4.0
• Microsoft Windows NT Workstation version 4.0

SYMPTOMS

Windows NT allows you to specify multiple Domain Name System (DNS) servers so that names are resolved even if your primary DNS server is down. If your primary DNS server (the first name in the list) does not acknowledge, Windows NT tries the next DNS server in the list.

However, if the primary DNS server does acknowledge that the name to be resolved is not found in it's database, the DNS lookup will fail and Windows NT tries the next form of name resolution, such as HOSTS or Windows Internet Name Service (WINS) depending on the node type defined.

This can lead to a problem if you have a local DNS server for local name resolution and a remote DNS server for Internet name resolution. Because a reply is normally returned from the DNS server that is first in the list, you never get names resolved that only exist on the second DNS server. Thus, you can only resolve local names or remote names, but not both.

RESOLUTION

To use a local DNS server for local name resolution and a remote DNS server for Internet name resolution:

Create a HOSTS or LMHOSTS file or use WINS for local name resolution.

-or-

Configure the DNS servers to forward requests to each other. This way, if a name is not found in one DNS server database, that server queries the other DNS server for the name and then returns it to the client.