Hosts file modifications for testing your website

During the development or migration of a website, it is often useful to be able to test it on a new server before making changes to the actual DNS servers. This is possible with a simple modification to your local hosts file.

What is the hosts file?

The hosts file functions as a local “DNS server”. When your computer tries to translate a domain name (such as mydomain.gr) into an IP address, it first checks the hosts file locally on your computer. If it finds a match there, it uses that and does not query external DNS servers.

Example usage:

Let’s assume your website mydomain.gr is hosted on the old server, but you want to test it on a new server with IP address 12.34.56.78, without changing anything for other visitors.

Simply add the following two lines to the hosts file on your computer:

12.34.56.78 www.mydomain.gr
12.34.56.78 mydomain.gr

This way, only you will see the page from the new server, while other users will continue to see the old one.

Instructions for different operating systems:

Below you will find information on how you can make the change on different operating systems.

Windows 11, 10 & Windows 8:

1. Press the Windows key on your keyboard.
2. Type Notepad in the search.
3. In the search results, right-click and run as administrator.
4. From Notepad, open the file C:\Windows\System32\Drivers\etc\hosts
5. Make your changes to the file.
6. Finally, save the file.

Windows 7 & Windows Vista:

1. Click Start > All Programs > Accessories.
2. Right-click and open as administrator.
3. Windows will need your permission to open Notepad, click Continue
4. In Notepad, click File > Open.
5. In the File name field, paste C:\Windows\System32\Drivers\etc\hosts
6. And click Open.
7. Make your changes to the file.
8. Finally, save the file.

Linux:

1. Open a new Terminal
2. Type the command sudo nano /etc/hosts
3. Type your user password
4. Make your changes to the file.
5. Press Control – X
6. Finally, press Y to save the file

MacOS X (10.6+):

1. Go to the Applications > Utilities folder and open Terminal
2. Type the command sudo nano /private/etc/hosts.
3. Type your user password.
4. Make your changes to the file.
5. Press Control – X
6. Press Y to save the file.
7. Finally, type the command dscacheutil -flushcache.

After your tests or when the DNS is officially updated to have this new IP, you must edit again to remove these lines you temporarily added.