What is 127.0.0.1?

127.0.0.1 is the loopback address, which refers to the local machine and is generally used for testing; that is to say, "127.x.x.x" is the loopback address of the local machine, which is the IP address inside the host IP stack and is mainly used for network Software testing and local machine inter-process communication.

127.0.0.1 is the loopback address, which refers to the local machine and is generally used for testing. The loopback address (127.x.x.x) is the local loopback address (Loopback Address), which is the IP address inside the host IP stack. It is mainly used for network software testing and local machine inter-process communication. No matter what program, once the loopback address is used to send data, The protocol software returns immediately without any network transmission.

The IP address consists of two parts, the network address and the host address. The network address indicates which network on the Internet it belongs to, and the host address indicates which host in the network it belongs to. The two are in a master-slave relationship. The four major types of IP addresses identify a certain host on the network. The IPv4 address length is 32 bits and 4 bytes in total, but in practice we use dotted decimal notation.

IP addresses are divided according to the network number and host number, and are divided into three categories: A, B, C and special addresses D and E. Leave all 0s and all 1s unused.

Class A: The first byte is the network number, and the last three bytes are the host number. The beginning of this type of IP address is "0", so the network number of the address ranges from 1 to 126. Generally used in large networks.

Class B: The first two bytes are the network number, and the last two bytes are the host number. The first part of this type of IP address is "10", so the network number of the address ranges from 128 to 191. Generally used for medium-sized networks.

Category C: The first three bytes are the network number, and the last byte is the host number. The beginning of this type of IP address is "110", so the network number of the address ranges from 192 to 223. Generally used for small networks.

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