127.0.0.1 Local IP Address

127.0.0.1 is the loopback address, referring to the local machine, typically used to test use. Loopback address (127.xxx) is the local loopback address (Loopback Address), the host IP address within the IP stack, network software is mainly used for testing and the local machine inter-process communication, no matter what the program, by using the loopback address to send data immediate return of the protocol software, without any network transmission.
Loopback address: 127.0.0.1. Generally used for testing. For example: ping 127.0.0.1 to test the local TCP / IP is working
IP addresses in a class of provisions, the first part is from 1 to 126 for the Class A address, 128 ~ 191 for the Class B address, then the middle left of the local loopback address 127.0.0.1 is called, has two main effects: first, test the machine’s network configuration, can PING 127.0.0.1 instructions through the network card and the machine IP protocol installed, no problems; Another effect is that some SERVER / CLIENT application to be invoked at run-time resources on the server, generally SERVER’s IP address specified, but the program to run on the same machine when no other SERVER SERVER resources can be installed in the machine, SERVER’s IP address 127.0.0.1 is also set to run.
For most of the practice of using localhost to run, essentially pointing to the local IP address 127.0.0.1. In the operating system has a configuration file to localhost and 127.0.0.1 to bind together.
127.0.0.1 is for the site builders often used.
We used “ping 127.0.0.1″ command in the loop on this machine to do the test, to verify the machine’s TCP / IP protocol stack is correctly installed. But you find it? Use “ping 127.1″ This command can also get the same results, in fact, “ping 127.1″ and the “ping 127.0.0.1″ is the same as the two commands are conducting loop test.
Why is it so? This is the Ping command in the IP address of the application tips. As we all know, IP addresses from 32-bit binary numbers, for the convenience of all memory, each 8-bit binary numbers converted to decimal numbers, and therefore formed by the four-part easy to remember the IP address of decimal digits (such as 127.0.0.1 .) Because, Windows operating system with automatic fill “.0″ feature, so I can be “127.0.0.1″ to “127.1.”
However, the “.0″ omission is conditional, and can not be arbitrarily omitted. Ping command in the application, the only IP address in decimal number appears before the last part of one or more “.0″ is omitted, such as the “ping 127.0.0.1″ command rewritten as “ping 127.1″.