Alright, so as we see you're father is a defence personal.  After you fill the form and results are out, you fill the respective details of your results while applying for counselling.

Now this defence quota is available in very few states, so you have to carefully fill the  that respective state. While you do that, you'll see various quota slots provided .

For e.g we have D1. D2 & D3  slots with varying criteria for defence personals in Maharashtra with limited number of seats. Go through the criteria, and select that matches yours.

Once the list is out , you can see what is your rank in that respective quota slot and see whether you come under the rank to get those limited number of seats or not