A: IP address: (1) to identify a separate host on the network (2) IP address = address + host address network (3) special address: 127.0.0.1 represent the address (typically used for testing)
B: Port number: (1) the logical address used to identify the process (2) different processes have different logical addresses
C: Transfer Protocol: (1) Rules of communication: TCP, UDP (2) TCP protocol through the three-way handshake, reliable transmission, but inefficient, slow (3) UDP direct throw in the past, regardless of whether the other there is a corresponding transfer rate high , low reliability, generally used for video, voice calls