The Tcpip subkey stores configuration data for the Microsoft implementation of TCP/IP. TCP/IP is a set of networking protocols that enable communication over diverse interconnected networks.
The Tcpip subkey stores some of the configuration data for TCP/IP (Transmission Control Protocol/Internet Protocol), primarily the settings for the TCP/IP service. Other registry subkeys, such as those for network components and services related to TCP/IP (such as DHCP, NetBT, and Winsock), also store entries that affect the operation of TCP/IP internet protocol implementation on your computer.
To change the values of many of the entries in the TCPIP subkey and its subkeys, use Network and Dial-up Connections. Right-click Local Area Connection, click Properties, click Internet Protocol (TCP/IP), and then click the Properties button.