Just wanted to clear a misconception. DOT doesn't approve helmets. DOT has certain standards. Helmet manufacturers then state that they have met those standards.
Since DOT is American, if the helmet is being sold in America, it may be tested at random to see if those standards have been met.
A company that claims their helmet to be DOT standard in India cannot be taken at face value. Since the company's claim cannot be verified in India.
Only if a helmet manufacturer sells the exact same model in America, does that DOT claim hold true
Absolutely. It's always advised to stick to reputed ones. I picked mine from London just to be sure I'm not joking with safety