Internal sliding chances often depend on vacancies during the admission process. The idea is if the admission process were very smooth and all the seats were filled during the first round there wouldnt really be any need for internal sliding.

You get to upgrade to higher ranked branches if you do really well in first year and people fall out of courses in those upper branches. Its not there in all NITs so dont rely on this to get the branch that you want.

Having said that, I personally know two batchmates of mine one who transitioned from IT to CS during the internal sliding round and the other one who went from IT to EC, both of them being DASA candidates.

Having said that it is more based on your luck than your marks. So keep your fingers crossed and hope for the best. Best of luck for your future.

Say you have entered the college with computer science. After an year(1st year) there's a provision that the students, if they want, may change their faculty, they can opt other branch like mech. (or any other). If theirs vacancy in that opted branch(or if that branchs student want some other branch, his seat will be vacant) then that vacant will be given to him. The seat is given(allotment) on the basis of merit.
Only few colleges support this system
Thank You:)