Sorry that my question is not specific to win7. I could not find a general networking forum. Hope you network gurus can help.MTU is bound to network adapter:MTUKey:Tcpip\Parameters\Interfaces\interfaceGUIDValue Type: REG_DWORDnumberping -f -l [packetsize] [www.yourisp.com] is used to test for the MTU value (try different sizes until unfragmented packet gets back).On my machine, I have two network adapters, one local Ethernet, one wireless. As far as I can see, both are connected to internet. How do I specify adapter in using Ping to get MTU value for each adapter and then I can change the registry accordingly?

The simplest waymight beto disable one at a time. You could, for example, temporarily unplug the Ethernet cable, or disable the radio.Sorry for stating the obvious.Are you experiencing a specific problem that's got you looking to change your MTU size, or just trying to do tuning in general?-Noel

Thanks Noel! I just try to do tuning in general.I wonder if I use socket API to ping, there should be a way in winsock for specify an adapter.