D&D's license covers dozens of different settings, including pretty much any major variety of fantasy one would care to name.
Their most popular setting - Forgotten Realms - is defined as the most vanilla, though, and is the most likely locale for a film.
I've been DMing D&D for more than 25 years so I'm aware of the minutia involved.
I'm working under the assumption that a D&D movie, just like the terrible one with Jeremy Irons, would just be a D&D movie, and not a Forgotten Realms, Greyhawk, Eberron movie or what have you. And the generic D&D setting, what 4e called "points of light" is as vanilla as it gets.