Failure to Specify All DNS Zones in Proxy Client Leads to DNS Failures That Are Difficult to Track (280833)

SYMPTOMS

When the Winsock proxy client is installed, the Mspclnt.ini file may not specify all of the DNS domain suffixes that are being used. In particular, internal testing DNS domains such as test.company name.com may not be included. Because of this, you may receive "server not operational" error messages when you try to start some MMC snap-ins such as Active Directory Users and Computers, Active Directory Sites and Services, and so on.

You may receive the following error message when you open an Active Directory snap-in:

Naming information cannot be located because: The server is not operational.

CAUSE

This issue can occur because when the WSP client is installed, the Msplat.txt and Mspclnt.ini files are copied to the client. The Msplat.txt file contains the proxy's local address table (LAT). This is a range of IP addresses that is considered internal to the proxy. The client attempts to communicate directly with the destination if the address falls within the LAT. The Mspclnt.ini file contains a "LocalDomains=" entry that specifies domain suffixes for names to resolve by using the client's DNS server entries. If a DNS domain suffix is not in the "LocalDomains" list, all GetHostByName() calls are remoted to the Winsock proxy server and the proxy's DNS server (typically external) is used.

RESOLUTION

To resolve this issue, add the local DNS domain or domains to the "LocalDomains" list in the Mspclnt.ini file (as the last line of the [Common] section), for example:

LocalDomains=.companyname.com,.corp.companyname.com

NOTE: You can add local domain names to the client's configuration on the proxy server to ensure that future installations of the proxy client receive the correct information to begin with. Also, the client's Mspclnt.ini file may be periodically updated to match the server.

NOTE: It is recommended that you stop and restart the Winsock Proxy service by using the IIS Management Console after you save changes to Mspclnt.ini on the server.

To obtain the new Mspclnt.ini file, double-click WSP Client in Control Panel, and then click Update Now. You can compare the client's Mspclnt.ini file to the copy on the proxy server by viewing Mspclnt.ini in the client's C:\Mspclnt folder.