Based on a quick internet search of domain information, it appears to be registered through a domain broken in Queensland, Australia ... who in turn has probably leased it, Go-Daddy.com style, to whitehouse.gov who have set things so that it redirects to that site.
I've seen this done other times as well. One of the webcomics I enjoy ("Dumbing of Age, by David Willis) featured a story arc a few years ago
(my, how time flies!) about the protagonist's brother (Joshua, a budding writer) and at one point in the comic he gave someone his website — JocelyneJBrown.com
(yes, the character is someone who is male-to-female transgender but still has not opened up to his/her family about it); the artist registered that specific site address and has it set up to redirect to the comic's home page.
Makes me wish I had some extra money on hand. Imagine the fun I could have if I created a site like "wesw.com" and set it to re-direct to the DNC or Hillary Clinton website.
Back to the matter at hand, however. It might be interesting to see how the Trumpmeister would respond to a blunt, direct question about whether or not this was a valid and worthwhile use of US government funds, however ... although I'm sure he and his sycophants would see it that way.
-"BB"-