What is 127.0.0.1?

127.0.0.1 is a customary IP address which is used for a loop back connection? It corresponds to the host computer. 127.0.0.1 is used when a program requires an access to a network service running on the same computer as itself. Mostly the loop back address is used as a development and testing address but it can also be used to access local services, like web servers, that can only be accessed on a network and which have no local interface.

The modern day PCs regard 127.0.0.1 as the “Local Host”. It is defined by the TCP/IP protocol as a reserved address that routes packets back to host. So no computer can be identified as 127.0.0.1 either it is connected to the internet or some TCP/IP complaint network. 127.0.0.1 is defined by the Internet Engineering Task Force’s RFC 3330.

Any public router that receives a packet intended for a special- use IP has to drop it, without sorting its contents. Thus if such kind of a packet is accidentally forwarded outside of its host it would not arrive at any other location. This feature helps in providing the network security. Occasionally, some services can be activated unexpectedly by responding to such stray packets.

A triumphant ping request to 127.0.0.1 will verify that a computer's network interface card, its drivers, and the operating system's TCP/IP implementation are all functioning properly. Moreover, in addition to its use as a troubleshooting and local access tool, 127.0.0.1 is often used in practical jokes and scams. One of the most popular pranks is to assign first-year computer science students to either crack or otherwise explore 127.0.0.1. Many service technicians 'prove' their network's speed and reliability by having customers ping the loopback address. Many stories about the "World's Worse Hacker" performing a DDoS attack on 127.0.0.1 circulate the Internet.

source: freetechexams