The real question Ive heard being asked is "Veg or Non veg?" This in many places is used to ask the caste question without explicitly asking for caste.

The other question I've heard being asked of Indians is "what is your full name?" as most upper caste Indians indicate their caste in their surname/family name. If your surname isn't upper caste, you are likely to be silently dropped in many social situations.

So someone who eats meat and doesn't have an uppercaste name is a lower caste. However since some upper castes do eat meat the surname question gets them through.

The color of your skin is the third SELECT. At some point all of it seems like a DB query.

In many localities and apartment complexes across India you will find it difficult to get houses because of these simple questions. A brief stint in Bangalore was eye opening with real estate agents being super frank about caste specificity.