I do not have enough reputation to comment on Jirka 's answer , which is the correct answer.
I just wanted to add that this seems to work only for the www host. I tried this with others as "clients", but it did not work (just a full page served by Parse (no errors).
So, if you want a bare domain on the Parse host, you can do it, but in my tests you should have the host name of the application www .yourdomain.com in the "User" section of the Domain Settings.
James
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