127.0.0.1 is the loopback address, which refers to the local machine, which is commonly used for testing. The loopback address (127.x.x.x) is the native loopback address (Loopback address), which is the IP addresses inside the host IP stack, mainly used for network software testing and local machine interprocess communication, no matter what program, once send data using loopback address, the protocol software immediately return, Do not make any network transmissions. The IP address consists of two parts, the network address and the host address. The network address indicates which network is on the Internet, and the host address indicates which host it belongs to in the network. The two are master-slave relations. The four types of IP addresses identify a host in the network. The address length of the IPv4 is 32 bits, a total of 4 bytes, but in practice we use dotted decimal notation. IP address according to network number and host number, divided into a, B, C three class and special address D, E. All 0 and all 1 are reserved. Class A: The first byte is the network number, and the second three bytes is the host number. The first of these IP addresses is "0", so the network number of the address is between 1~126. Typically used for large networks. Class B: The first two bytes are the network number, and the last two bytes are the host number. The first of these IP addresses is "10", so the network number of the address is between 128~191. Typically used for medium-sized networks. Class C: The first three bytes are the network number, and the last byte is the host number. The first of these IP addresses is "110", so the network number of the address is between 192~223. Typically used for small networks.
127.0.0.1
