Modifying your hosts file enables you to override the domain name system (DNS) for a domain on a specific machine. DNS management is useful when you want to test your site without the test link prior to going live with SSL, verify that an alias site works prior to DNS changes, and for other DNS-related reasons. 

Modifying your hosts file causes your local machine to look directly at the Internet Protocol (IP) address that you specify. 

Modifying the hosts file involves adding two entries to it. Each entry contains the IP address to which you want the site to resolve and a version of the Internet address. For example, You would enter the following in the hosts file:

123.123.123.123 domain.com

If you are using a Microsoft operating system like Windows 10, Windows 8, Windows 7, and Windows Vista you must run Microsoft Notepad as an administrator.

Windows 10 and Windows 8
Use the following instructions if you’re running Windows 10 or Windows 8:

Press the Windows key.

Type Notepad in the search field.

In the search results, right-click Notepad and select Run as administrator.

From Notepad, open the following file:

c:\Windows\System32\Drivers\etc\hosts

Make the necessary changes to the file.

Select File > Save to save your changes.