Ephermal ports
TCP Ports in the range 1024 to 5000 are used when a connection is made outbound from a machine. There are approximately 4000 of them. After the connection is torn down, the port is unavailable for a period of time greater than the max Time To Live (TTL) for IP packets on the network. The easiest way to check is to run “netstat /a /n” on the server. If all the ports in this range are in CLOSE_WAIT state, then the server can not make our bound calls (for instance to the DC to authenticate). MSDN has articles describing how to raise this limit. http://support.microsoft.com/default.aspx?scid=kb;en-us;812873