They easily could, though, genius. All through simple dns entries. Go ask your teacher.

I wish I was in a web class...

They could doesn't mean they necessarily do and those "simple dns entries" become tedious when there's a lot of them, spread all over the globe, between various owners and companies and countries...

What in the world are you talking about? There is nothing tedious about it. You assign domain.tld to an IP address via dns and wait for propagation to occur.