An incorrect value is returned for the ifSpeed object in MIB2 on a Windows Vista-based or Windows Server 2008-based computer
On a computer that runs Windows Vista or Windows Server 2008, a Simple Network Management Protocol (SNMP) application queries the ifSpeed object in Management Information Base 2 (MIB2) to obtain the bandwidth of a network adapter. However, if the network adapter is not connected to any network, the system returns an incorrect value for the ifSpeed object. This returned value is 4,294,967,295 instead of zero.
Therefore, the SNMP application cannot detect the correct status of that network adapter.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB970663.