How do I use a custom domain?

I am going to redirect one of our domains to our Jotform URL however I'd like to mask it -- does Jotform allow masking?

Yes, you can use a custom domain and mask the form's link, still redirecting to your form and capturing submissions on the JotForm server, which means that you can access your submissions anytime by logging-in into your account. 

The following guide will help you to set up a custom domain with your form: https://www.jotform.com/help/144-How-to-use-Custom-Domains-with-Jotform 

If you have any question, let us know.