The Tcpip subkey stores configuration data for the Microsoft implementation of TCP/IP (Transmission Control Protocol/Internet Protocol). TCP/IP is a set of networking protocols that enable communication over diverse, interconnected networks.
This subkey stores some of the configuration data for TCP/IP, primarily the settings for the TCP/IP service. Other subkeys also store entries that affect the operation of the TCP/IP implementation on your computer. These other subkeys include those for network components and for services related to TCP/IP, such as Dynamic Host Configuration Protocol (DHCP), NetBT, and Windows Sockets (Winsock).
To change the values of many 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.