Virtual Servers and HOST Name Resolution

The information in this article applies to:

• Microsoft Internet Information Server version 3.0

SYMPTOMS

Internet Information Server (IIS) configured with multiple virtual servers can cause problems with applications that are running on a computer that performs a lookup of its own HOST name.

On a computer running Microsoft Windows NT Server with multiple IP addresses assigned to the same network interface card, resolving the computer's HOST or NetBIOS name will return the last IP address listed in the Network Control Panel Advanced TCP/IP Properties, rather than the first address listed. All other computers on the network that resolve this name will correctly get the first IP address listed.

WORKAROUND

If you are using DNS for name resolution, you can add an additional record for the same computer with a different name. For example, if your computer name is listed in DNS as WEBSERVER, you may also want to add an entry in DNS for WWW that refers to the same IP address.

In this case, when you type "PING WWW," the name is not resolved locally, but rather at the DNS server, and the correct IP address will be indicated in the reply.

STATUS

Microsoft has confirmed this to be a problem in Microsoft Windows NT version 4.0. This problem was corrected in the latest Microsoft Windows NT 4.0 U.S. Service Pack. For information on obtaining the service pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

   S E R V P A C K

MORE INFORMATION

The following is an example of this configuration:

   HOST name = MACHINE1
   Assigned IP Addresses #1= 192.168.1.1
   Assigned IP Addresses #2= 192.168.1.2
   Assigned IP Addresses #3= 192.168.1.3

If you are at another computer on the network, and you type "PING MACHINE1," your reply will indicate the 192.168.1.1 address.