====== Editing your machine’s hosts file / View a website as it appears on a different host ======
Change the domain’s A-Record (without changing the domain’s A -record)
===== What is the hosts file? =====
In the old days of the internet there was no DNS system. Everyone kept a copy of all the hosts (this
was before the days of websites) on the internet on a file on their computer. As new hosts were
added to the internet an updated hosts file was sent round everyone on the internet so they could
get their local copy updated. This system got out of hand as the internet expanded so it was replaced
by the DNS system.
===== What can I do with the hosts file? =====
You can override the DNS for a domain on your local computer. This lets you view a website (or user ftp etc.) as it would appear on a different server or host, as though the domain pointed to a different location even when it doesn't.
===== Why Would I Do that? =====
Let’s say I was looking at moving example.com to a different server. Currently the domain is pointed
to 93.184.216.34 and I’m going to be moving the site over to a new server at 123.123.123.123. I
want to see how the site would look on the new server but I don’t want anyone else to see it. By
adding a single line to my hosts file I can ‘repoint’ the domain to the new IP address but just for myself.
===== How do I do that? =====
You will need elevated permissions on whatever system you are using. If you are on a restricted
work computer this may not be possible.
==== On Windows ====
On Windows the hosts file is located at the following path:
C:\Windows\System32\drivers\etc\hosts
Find notepad or a text editor of your choice. Right click on it and ‘run as administrator’ then file open
and find the file with the path shown above (you may need to select the option ‘view all files’ to see
the file listed as it is not a txt file)
Add the line:
<code>123.123.123.123 example.com www.example.com</code>
This will point the both the domain and the www subdomain to the chosen IP address. You will need
to restart your browser for this to apply.
==== On Linux or Mac ====
On Linux or MacOS the process is the same except that the hosts file is located at /etc/hosts
The vim text editor can be used for this by running the command in the Terminal:
<code>sudo vim /etc/hosts</code>
Add the line:
<code>123.123.123.123 example.com www.example.com</code>
This will point the both the domain and the www subdomain to the chosen IP address. You will need
to restart your browser for this to apply.
===== Undoing the process: =====
You can re-open the hosts file using the same method as described above, delete the offending lines and save the file. (Don't forget to restart your browser for it to apply again.)
Another option is to comment out the offending line. Adding # before any line in the hosts file comments it out. (So the text will remain but it will not do
anything.)
~~NOTOC~~
{{htmlmetatags>metatag-keywords=(hosts, file, preview, domain, dns) 
metatag-description=(How to preview your website on another server by editing your computers hosts file.)
}}