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What Is a Hosts File?

In the realm of Information Technology, understanding the intricacies of computer networks is essential. One aspect that often goes unnoticed yet holds significant importance is the hosts file. Comprehending its function and how to manipulate it can prove beneficial for IT professionals and enthusiasts alike.

What is a hosts file

The hosts file is a plain text file in an operating system used to map hostnames to IP addresses. In the early days of the internet, this file was utilized to resolve hostnames before the Domain Name System (DNS) came into existence. Today, it plays a critical role in network administration, configuration, and troubleshooting. If you want to know if a hosts file has been changed, you can check for modified hosts files using Powershell.

4 main uses of the hosts file

1) Local website testing

The hosts file is often used for local website testing. When a new website is being developed, it may be necessary to test it before it is made live. By using the hosts file, the website can be mapped to the IP address of the local development server. This allows for the website to be tested in a controlled environment without affecting the live version of the site.

2) Blocking access to malicious websites

The hosts file can be an effective tool in enhancing cybersecurity. If there are known malicious websites that pose a threat to the system, these can be blocked using the hosts file. In this case, the dangerous URLs are redirected to a local or non-existent IP address. As such, attempts to access these sites will lead to an error, thus protecting the system from potential threats.

3) Speeding up the resolution process

Bypassing the DNS lookup can be achieved by using the hosts file. When a hostname is entered into a web browser, the system typically uses a DNS server to look up and translate the hostname into an IP address. However, if the IP address corresponding to the hostname is already specified in the hosts file, the system will use this information instead. This can significantly speed up the resolution process.

4) Blocking or redirecting specific websites

The hosts file can be utilized for productivity or parental controls. If there are specific websites that are considered distracting or inappropriate, these can be blocked or redirected using the hosts file. By redirecting the hostnames of these sites to a local or non-existent IP address, access to these sites can be effectively controlled.

Editing the hosts file in Windows

To modify the hosts file in a Windows environment, one must navigate to its location, which is typically C:WindowsSystem32driversetc. Before proceeding with any changes, a backup copy of the original file should be made. The file can then be opened with a text editor such as Notepad. New entries can be added by specifying the IP address, followed by the hostname. After the necessary changes have been made, the file must be saved without any extension.


The hosts file is an integral part of the operating system that allows for the mapping of hostnames to IP addresses. Its uses are diverse, ranging from local website testing to parental controls. Understanding how to edit this file in a Windows environment can enhance one’s IT skills and open doors to more advanced networking tasks. Therefore, a comprehensive understanding of the hosts file is a must for any IT professional or enthusiast.

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