localhost

Localhost is in the network technologies for the currently used system or its IP address.

Usually, your own system ( localhost ) at IP address 127.0.0.1 for IP applications accessible in the same way as a remote system ( a remote host ) under a common address. This makes it possible to operate under other server applications with a client on the same machine. Such an approach is used for example when testing servers, or for operating game servers frequent use.

In order to allow the reachability of the own computer via IP, an interface, a so-called loop-back device is used. This behaves like a virtual network card that forwards all outgoing data packets to their own entrance. However, this virtual network card has no connection to any existing network interfaces; sent to 127.0.0.1 packages can not appear on a physically existing link to another system, therefore, in the normal case. In general, each of the addresses from 127.0.0.1 to 127 255 255 254 ( 127.0.0.0 / 8 subnet) as loopback device is usable.

Instead, the address 127.0.0.1 :: 1 is used for IPv6.

RFC 2606 reserved localhost as a top -level domain for the Domain Name System (DNS). You should have a static A resource record contains the IP address of the loopback interface. In the local hosts file also usually the hostname localhost is defined so that the name resolution of localhost can also be done without accessible DNS server.

Specifications

• RFC 2606 - Reserved Top Level DNS Names
• RFC 4291 - IP Version 6 Addressing Architecture
• RFC 6890 - Special Use IPv4 Addresses

• Computer Networks