Name Resolution Slow over RAS Connection

• Microsoft Windows NT Workstation version 4.0
• Microsoft Windows NT Server version 4.0

SYMPTOMS

You are running Windows NT 4.0 on a portable computer connected to a LAN, and your network adapter receives a TCP/IP address from a DHCP server. DHCP also assigns a WINS and DNS server address to your network adapter.

When you remove your computer from the LAN and use RAS (Dial-Up Networking) to connect to a remote server, you find that name resolution slows down by at least sixfold (for example, names formerly resolved in 10 seconds now take at least 60 seconds).

CAUSE

The cause of this problem is that the DNS server addresses remain bound to your network adapter. The result is that your client attempts to resolve host names through DNS servers that are not available because your computer has been removed from the network.

Using IPCONFIG /RELEASE from the command prompt will not release the DNS server address(es) bound to your network adapter.

NOTE: If you have multiple network adapters in your system, these adapters will also continue to use the DHCP assigned DNS server address(es).

WORKAROUND

To work around this problem, on the Windows NT 4.0 Dial-Up Networking client, do one of the following:

• Configure the RAS server with a DNS address. This address will be given to RAS clients. RAS clients will use this DNS first and there should be no delay resolving names.

• Use the Windows NT 4.0 Hardware Profiles option to create a remote hardware profile that eliminates the network adapter on the Windows NT 4.0 remote client. In the Control Panel, double-click the System icon and click the Hardware Profiles tab to find this option. Use the context help file for assistance in creating the remote profile without a network adapter. The Hardware Profiles option automatically creates a boot menu so you can choose between your local and remote profiles.

• Use the Registry Editor to the remove reference to the legacy DNS server entry.

  WARNING: Using Registry Editor incorrectly can cause serious, system- Wide problems that may require you to reinstall Windows NT to correct them. Microsoft cannot guarantee that any problems resulting from the use of Registry Editor can be solved. Use this tool at your own risk.

  To remove the DNS server addresses from your network adapter, follow these steps:

  1. Run Registry Editor (Regedt32.exe).

  2. Go to the following key in the registry:

        HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\
        Parameters\DhcpNameServer
  

  3. Double-click the DHCPNameServer entry in the right pane window, and

        select the DHCP assigned name server addresses. Now, pinging a Host
        name or a NetBIOS name over the RAS connection take the expected
        amount of time (without significant delay).
  

        The change is immediate, and you will not have to restart after
        making this change. After you disconnect from the Dial-Up Networking
        remote connection and reconnect to your LAN, run the IPCONFIG /RENEW
        command at the command prompt to restore the original DNS server
        settings.
  

• Ensure that you have specified a DNS server that is valid for your remote network in the "Specify name server addresses" option of the PPP TCP/IP Settings dialog found in your Edit Phonebook Entry window for the Windows NT 4.0 Dial-Up Networking interface.

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 4.0. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.