what are the four main place for the exams

Hello,

Your question is confusing. On the part of location, there is nothing important. The officials give you a location near to your address or as per your preference. Most of the students choose places near to their home address or they have in their home town itself. Test center is preferred near as there won't be a trouble for travelling. This mostly hampers the consistency of candidates as they get into lots of stuffs to travel.

Anyway the officials do their work best to provide as comfortable place as possible.

Hope it helps!