Hi

Since you did not mention any particular entrance test. I assume you are talking about JEE as your profile shows Engineering aspirant.

For this, you have two major all India exams named JEE Main and JEE advanced. After you qualify JEE Main, you will be allowed to appear to in JEE Advanced.

JEE Main is conducted for providing admission into BE or B.Tech courses in various NITs & other Institutions all over the country. JEE Advanced is the criteria to get admission in the well-known Indian Institutes of Technology (IITs).

Coming to rank. It depends.  If you are aaiming for NIT, IIIT GFTIs etc, any rank below 20k-30k (General rank) will fetch you a good seat. Rank below 5k in JEE mains will get you into some of the top NITs of the country. While for JEE Advanced any rank below 5k (General Rank) would easily fetch you an IIT.

Hope it helps