Most forms ask you to fill your parents name and they also ask you to fill your reservation group, that is general, OBC or SC/ST(schedules class/tribe).
A lot can be gathered from this.
Even if you lie, there are background checks for this.
The smarter parents, register their kids as something generic like "kumar" or "singh" in schools.
Interesting, I've often seen CVs from people applying from India include their parents' details. I assumed it was something to do with caste but I was still surprised to see it added even when not required.
An even better approach is to just change your religion. I was born a hindu dalit but I converted and so have many of my friends and family. Religious conversions have become so common in India that states have started to bring out laws to curtail it. Casteism is a construct of Hinduism and other religions don't suffer from it in the same way as Hinduism does. So you can change your religion , your name and claim that you have no caste. Hindus have no problem seeing a converted christian as equal to them, but will refuse to see people from their own religion as equal.