For the dead gateway detection to work correctly, you must specify more than one default gateway address in the Advanced Options of the TCP/IP configuration dialog box in the Network portion of Control Panel. If the default gateway fails to respond to TCP requests after several tries, IP will direct packets to the address specified for a backup gateway.
Windows NT will switch to the next default gateway on the list. When the original default gateway comes back up, it broadcasts its routes to other intelligent routers.
When Windows NT tries to access a network through the current default gateway, it will be informed of a better route (the original default gateway). Windows NT will add a host route to it's routing table, but will NOT switch back to the original default gateway. To switch back to using the original default gateway you will need to reboot the Windows NT Server.
Note: If the second default gateway becomes unavailable, it will switch to the next default gateway configured on the list. When the end of the list of default gateways is reached, the search returns to the beginning again.
For information about obtaining a RFC document, please see the following article in the Microsoft Knowledge Base:
Value Name: EnableDeadGWDetect
Value Type: REG_DWORD
Value Range: 0 or 1 (False, True)
Default setting is 1 (True)
For additional information about dead gateway detection in Windows NT, click the article number below to view the article in the Microsoft Knowledge Base:
Article ID: 128978 - Last Review: Oct 31, 2006 - Revision: 1