Does Domino's use rennet-free cheese?
According to the nutritional information posted on their website Domino's uses a blend of Mozzarella, American, Cheddar, Feta, Parmesan, and Provolone Cheeses. 

Somebody, apparently, with similar concerns asked Domino's and received this response: 

excerpt from letter, emphasis added:


  Domino's Pizza Diced Cheese for Pizza is a specially produced cheese
  made exclusively for our use. It is a natural dairy product, produced
  from cultured, pasteurized milk, rennet; and salts of calcium and/or
  sodium. The type of rennet used in the production of this cheese is
  restricted to a microbial-based rennet or a genetically-engineered
  rennet. Animal derived rennets will not be allowed.
  
  As far as the other cheeses (Cheddar, Parmesan, Provolone, etc.),
  Domino's does not specify the source of rennet used in these products.
  They may or may not contain animal rennet. This depends on the
  supplier's current source and is always subject to change without
  notification to Domino's Pizza.