How to increase maximum connection backlog limit in windows 2008 server

Question

I have a Windows 2008 Server. Its maximum connection backlog limit (TCP) is 200. Is there any way to increase this limit to a higher value – say 1000 or 2000?

In this article you will find description of parameters to change in the registry under this key:

• HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\AFD\Parameters

The relavant values should be these:

• EnableDynamicBacklog (DWORD)
• MinimumDynamicBacklog (DWORD)
• MaximumDynamicBacklog (DWORD)
• DynamicBacklogGrowthDelta (DWORD)

I have tried using different sets of values like

• EnableDynamicBacklog = 1
• MinimumDynamicBacklog = 250
• MaximumDynamicBacklog = 20000
• DynamicBacklogGrowthDelta = 100

and

• EnableDynamicBacklog = 1
• MinimumDynamicBacklog = 20
• MaximumDynamicBacklog = 1000
• DynamicBacklogGrowthDelta = 10

but no matter what I do I am still limited to a backlog of 200 connections. (And yes I have rebooted the server between configuration changes.)

Any ideas?

Answer 1

Syn Attack protection has been implemented in TCP/IP stack of Vista and later OS. Therefore these registry parameters are no longer relevant.

Please refer to this technet article for more information about Syn Attack protection.