If I'm being hosted at instructure.com, and I own the domain example.edu and want to set up a cname for canvas.example.edu to point to example.instructure.com, that would require me to have the cert at example.instructure.com updated to include canvas.example.edu (so that users would see canvas.example.edu in their url bar). Is that even possible?
If you are hosted by Instructure, this is something that you can contact your Customer Success Manager for. They have the ability to provide you with a solution. At my institution, we have a log in page for our LMS, http://learn.nmsu.edu, but once they log in it goes to nmsu.instructure.com.