Updating host file in vista
By default, host to IP address mappings that are configured in the Hosts file supersede the information in DNS.
The hosts file contains lines of text consisting of an IP address in the first text field followed by one or more host names.
Each field is separated by white space – tabs are often preferred for historical reasons, but spaces are also used.
Comment lines may be included; they are indicated by an octothorpe (#) in the first position of such lines. For example, a typical hosts file may contain the following: This example only contains entries for the loopback addresses of the system and their host names, a typical default content of the hosts file.
It is a common part of an operating system's Internet Protocol (IP) implementation, and serves the function of translating human-friendly hostnames into numeric protocol addresses, called IP addresses, that identify and locate a host in an IP network.
In some operating systems, the contents of the hosts file is used preferentially to other name resolution methods, such as the Domain Name System (DNS), but many systems implement name service switches, e.g., for Linux and Unix, to provide customization.