Hello,

If you are asking about IIT BHU,  then you have to appear JEE advance and if your rank is in the cutoff range then you can join the institute.

if you are asking for any other college then a rank below 5-10K will be enough to join for CSE branch. For top colleges or 1st tier colleges the cutoff rank for CSE is almost below 1k.

Cutoff rank varies college wise so if you looking for any 1st tier college then try to get a rank below 5k which means a mark above 300.

Hope it helps!