What kind of cheese does Pizza Hut or Domino's use?
Pizza hut uses skim milk mozzarella on it's pizza, at least in the USA.  Not sure what they use in other countries, but I would imagine it is still the same.  Skim milk mozzarella is extremely stretchy, but loses a little on the flavor end.  More expensive pizzerias normally spring for the full fat mozzarella cheese.

Dominos uses a mix of cheese, made up of mozzarella, Pecarino, Parmesan, and asiago cheeses. I think in their most recent reboot they switched to part skim mozzarella but I am not one hundred percent on that.