If you're using a root domain (like "www.mysite.com") you might want to set up the naked domain, so that visitors who don't add the "www" will still be directed to your landing pages. To do that, you'll need to set up an A Record in GoDaddy:
If there are any errors when you try to save your zone file, GoDaddy will show a message explaining the errors. You'll usually see this if you're trying to create a CNAME record for a sub-domain (host) that already has an existing A Record. More often than not, it's when you try to create a CNAME record for your "www" subdomain.
To fix this up, delete the A Record for your "www" subdomain then create the CNAME record as outlined above.
If you've followed these steps and are still experiencing difficulties with your custom domain, take a screenshot of your current DNS setup and contact us at email@example.com.