0x1–0xFFFFFFFF ( milliseconds )
0x3E8 ( 1,000 milliseconds = 1 second )
Determines how often TCP repeats keep-alive transmissions when no response is received. TCP sends keep-alive transmissions to verify that idle connections are still active. This prevents TCP from inadvertently disconnecting active lines.
Windows 2000 does not add this entry to the registry. You can add it by editing the registry or by using a program that edits the registry.