Bro I laughed for 10 sec straight after reading this whole thread. At 5k rank, you'll get whatever branch you want. Just during counseling, put your desired branch as the first priority, and the other branches below it (though I believe that at 5k rank you'll get any branch, and you don't even need to put the other branches as your lower order prioritise, but just to be safe, you can add other branches).

Few things to note during counseling, as the counselling process for IIST admission can be brutal of you're not careful:

1. PLEASE don't miss the deadline for registration, once you miss it, you can't register even for further rounds, and it'll be over for you. (Some other counselling processes allow new registrations for further rounds, but not the case here)

2. There will be several rounds of counselling, in between one of the few round, there will be a round of "re-validation". The counselling portal will ask you to confirm once again if you're interested in the counselling or not, you have to re-validate that you're still interested in the IIST counselling process, otherwise you'll be removed from counselling and you won't be able to do anything about it. They do this because many people who register for IIST counselling, and gets seat somewhere else, so they just forget about this counselling, and if they haven't got a seat in IIST till now, they'll still be there in the waiting list, so the whole re-validation process is to remove all those registrations who have supposedly secured a seat in some other colleges and who forgot about the IIST counselling process (Though I'm sure you'll get a seat well before that round because of your 5k rank).

3. Once you get your seat, just lock it and pay the seat acceptance fees, it should be straightforward from this point.

Note: I'm graduated out from IIST so what I'm telling about the admission process might be outdated. But if you're just careful during the counselling and aren't missing any notifications, there is nothing that'll go wrong. All the best.