Transmission Control Protocol (TCP) provides a connection-based, reliable byte-stream service to applications. Microsoft networking relies upon TCP for the logon process, file and print sharing, replication of information between domain controllers, transfer of browse lists, and other common functions.or TCP connections made from a multihomed host, if the connection is a Winsock connection using the DNS namespace, once the target IP address for the connection is known, TCP attempts to connect from the best source IP address available.