After document verification, actual interview was only a couple of minutes with questions about your masters thesis and linking with their project. Read up on their project and on your own thesis well.

Walk-in interview, wherein one had to bring all original documents from class tenth grade mark sheets to degree and an attested copies of same. Document verifications done on spot and then only one can be interviewed. Sometimes candidates are asked their eligibility for national qualifying exams like CSIR NET, GATE