Setting up a server for Global DNS is a 3 step process.
Step 1: Get the files for server
Step 2: Put the files on server
Step 3: Add server details on your site.
Keep on repeating all above steps for each server that you add.
You have to visit this website here and follow below process:
Finally, you click on "Download File" button, this will prompt you to download a file.zip and also system will provide you a URL at the top, don't forget to copy that URL.
You will have to login to your server via FTP or cPanel -> File Manager. Upload the zip file in public_html or similar folder. And make sure you delete the zip file after extracting it.
Now, goto your WordPress or Global DNS Standalone site where you had installed Global DNS and goto Server section. Put appropriate details and URL as the one which you copied in Step 1.
And that's it! You can also refer to the video below which shows how to create a server for Global DNS.
If you're getting this error in your Global DNS, then just check if you're using right Longitude and Latitude values.
Here are the minimum and maximum values for them
Longitude: -180 to +180 Latitude: -90 to +90
If your values are within the range and you're still getting error, please create a ticket and we will get this sorted out ASAP!