Topic Last Modified: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool queries the Win32_NetworkAdapterConfiguration Microsoft Windows® Management Instrumentation (WMI) class to determine the count of instances of the DefaultIPGateway key. Each network adapter publishes its configured default gateway address to WMI through this key. If the Exchange Server Analyzer determines that there is more than one configured instance of the DefaultIPGateway key, a warning is displayed.

This warning indicates that multiple network adapters were found, and that more than one of those adapters has a configured default gateway. When multiple adapters are used and configured with separate default gateways, connectivity to computers on remote networks may be lost. Additionally, using multiple default gateways that link to different network subnets is known to cause problems with Domain Name System (DNS) resolution, Simple Message Transfer Protocol (SMTP) message delivery, Lightweight Directory Access Protocol (LDAP) queries, and new mail notification to Microsoft Office Outlook® 2003 clients. Many of these problems can prevent Exchange Server from starting, or from sending and receiving messages.

It is recommended that you remove all except one default gateway from one of the network interface adapters in the Exchange Server computer. Exchange Server computers are often multihomed when Microsoft Internet Security and Acceleration (ISA) Server has been installed on the same computer. Even when you run Exchange Server and ISA Server on the same computer, using multiple default gateways is not recommended. If Exchange Server and ISA Server are not installed on the same computer, it is recommended that you do not multihome an Exchange Server computer.

To correct this warning

  1. Open the Network Connections window. Either right-click My Network Places, and then click Properties, or if My Network Places is not displayed on the desktop, click Start, click Programs, click Accessories, click Communications, and then click Network Connections.

  2. In the Network Connections window, right-click the network connection containing the default gateway entry you want to remove, and then click Properties.

  3. Select Internet Protocol (TCP/IP), and then click Properties.

  4. Delete the IP address from the Default gateway field.

  5. Click OK twice to save the changes.

  6. Repeat this process for all other network connections that contain a default gateway entry, except for the one entry you want to keep.

For more information about problems encountered on computers that use multiple default gateways, see the Microsoft Knowledge Base article 159168, "Multiple Default Gateways Can Cause Connectivity Problems" (

For more information about configuring default gateways on multihomed computers, see the Knowledge Base article 157025, "Default Gateway Configuration for Multihomed Computers" (