How do you add authorized hosts in Target?

Good day all,

I'm following the documentation at What are Hosts and How Do I Use Them? | Adobe Target and the on-screen instructions, but I'm not getting expected results. 

The documentation says to place hosts on new lines, doesn't mention commas, and the error message says no new lines (says no to a lot of things). The help text says use commas, but the error says no. 

How have you entered authorized hosts?

Thanks all, -Brent