In fact, Hosts is a windows system file without extension, you can use notepad and other tools to open, its role is to some common web site domain name and its corresponding IP address to establish a correlation "database".
When the user enters a URL in the browser, the system will first automatically search for the corresponding IP address from the Hosts file, once found, the system will immediately open the corresponding web page, if not found, the system will then submit the URL to the DNS domain name resolution server for IP address resolution.
Hosts file for general users may not be to notice, in our general Internet and other applications set by default, but some times we need to achieve specific functions, such as we need to block a website, then you can modify the Hosts file to achieve this purpose, in addition to some viruses can also damage the file, resulting in the computer can not open the antivirus site or some other websites.
In a nutshell, the hosts file is a file in the Windows system responsible for IP address and domain name express resolution, saved in ASCLL format.
When a computer types in a domain name (such as www.chachaba.com), it will first look at the hosts file to see if there are any records about the IP address of this domain in the summary. If there is, it directly logs into the site; if not then it queries the DNS server. hosts is a hosts file in Windows 2000/XP.
Where is the hosts file?
Sometimes we can achieve blocking certain websites by modifying the hosts file, especially parents can use this method to block some SE sites to prevent children from seeing things they should not see, then you need to find the file and make the appropriate changes.
Host file is in the windows directory, generally our system is installed by default in the C drive, so the location of the file is: C:\WINDOWS\system32\drivers\etc folder.
It should be noted that the above windows display files are hidden and we need to set them up to show the hidden files in order to see them.
