The Hosts file contains the mappings of IP addresses to host names. This file is loaded into memory (cache) at startup, then Windows checks the Hosts file before it queries any DNS servers, which enables it to override addresses in the DNS. This prevents access to the listed sites by redirecting any connection attempts back to the local machine. Another feature of the HOSTS file is its ability to block other applications from connecting to the Internet, providing the entry exists. It’s a general practice of web developers to test any site locally by emulating the original web address pointing to a local or development server by modifying the hosts file. Here is a brief explanation on how to set it up properly.
Common Locations:
The host file is located in different locations in different operating systems and even in different Windows versions:
- Windows NT/2000/XP/Vista:
%SystemRoot%system32driversetcis the default location, which may be changed. The actual directory is determined by the Registry keyHKLMSYSTEMCurrentControlSetServicesTcpipParametersDataBasePath. - Windows 95/98/Me:
%WinDir% - Linux and other Unix-like operating systems:
/etc - Mac OS 9 and earlier: System Folder: Preferences or System folder (format of the file may vary from Windows and Linux counterparts)
- Mac OS X:
/private/etc(uses BSD-style Hosts file) - OS/2 and eComStation:
"bootdrive":mptnetc
Setting it up:
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