Edit your hosts file on a Mac to spoof DNS changes

Sometimes I need to spoof DNS changes before they go live, like when double-checking the behavior of a site in a production environment before the site launches.

You can do this by editing your Hosts file. By editing your Hosts file, you’re basically telling your computer, “Hey, ignore what all of the DNS caches are telling you about where to find this site. This is where you should actually look for it.”

All great and useful, but I forget how to do this every time. For future reference:

Open up Terminal (the command line) and run

sudo nano /etc/hosts

You’ll likely be prompted to enter the password for the user you have set up on your computer since sudo tells the computer to execute a command as a superuser, and it needs to make sure you’re authorized to do that. Once the command runs, the file you specified (/etc/hosts) will be opened up in the GNU nano command line text editor. Nano can be a little confusing if it’s super new to you, refer to the docs or search around, guides abound online.

There will probably be a bit of content in this file already. Some of it might be comments, text preceded by a # symbol. Don’t change the existing contents unless you know what the effect will be and you’re really sure about it!

Instead, on a new line at the base, just add a new line with the IP address you want to point to followed by the URL without the protocol (so piperhaywood.com, not https://piperhaywood.com).

Once you’ve changed it, save the file and exit nano. When you load up the URL in a browser, you should be seeing whatever resources are available at the IP address you’ve specified. If you’re still seeing the “old” site, try loading it in a private browsing window.

Don’t forget to change it back when you’re done.