Why am I getting ERR_NAME_NOT_RESOLVED when I add a site to my multisite installation? [closed]

About a year ago, I created a WordPress multisite installation consisting of 5 different websites. Each site is on a different domain in Production, and I’m using an external domain mapper plugin to make this work (I’m not using this plugin locally, only in Production).

I was able to add another site today, but when I tried to access it, I got a blank Chrome page with the “ERR_NAME_NOT_RESOLVED” error. I do not recall having this problem the first time around.

Is there an additional setting I need to account for, perhaps in my config.php or another file?

Upon further investigation, I found that the answer to my problem involved one simple, yet easy to overlook fix: I needed to add this new site to my hosts file.