I've seen a couple of people check to see if they're eligible and get back an answer of "no". This is a pure curiosity question, but I didn't think Equifax kne

I've seen a couple of people check to see if they're eligible and get back an answer of "no". This is a pure curiosity question, but I didn't think Equifax knew which numbers had and hadn't been leaked -- my impression was just that hackers got access to the full database. When the original announcement came out, wasn't there a big thing about how they were basically flipping a coin and returning a random result every time you checked if you were affected? Are they really able to determine which social security numbers were stolen?