URL masking for OJS?

I’ve got a question on behalf of one of my editors about configuring URL masking for OJS. URL masking is not something I’m familiar with so apologies if I’m a broken telephone here:

How do we configure domain masking/URL masking for an OJS journal? For instance, if the journal website is journal.org, it’s easy to forward that URL to journal.ojs.university.org (where it’s hosted). But, we want viewers of the website to see the URL remain journal.org throughout their viewing experience, including as they navigate (e.g., journal.org/index.php/default/about/EditorialTeam instead of journal.ojs.university.org/index.php/default/about/EditorialTeam).

Is this something we’d need to take care of via our institutional IT at York University, or do we do it via the domain registration? Or something entirely different?