An IP address can have up to 65536 ports (that is, 256×256)! Ports are marked with port numbers, which are only integers ranging from 0 to 65535(256×256- 1). It should be noted that the ports are not in one-to-one correspondence. For example, when your computer accesses the WWW server as a client, the WWW server uses the "80" port to communicate with your computer, but your computer may use the "3457" port. Dynamic ports range from 1024 to 65535. It is called a dynamic port because it generally does not allocate a service fixedly, but dynamically. Dynamic allocation means that when a system process or an application process needs network communication, it applies for a port from the host, and the host allocates an available port number for it to use. When this process is shut down, it also releases the occupied port number.