I am currently pursuing PhD from NIT-Surat. As far as interview questions are concerned, you must be aware of the field in which your area of interest lies. You will be directly asked questions about your master project/dissertation and also regarding the latest research or know how in the field you are applying to. There may be some technical questions regarding the basics from the same field.
This is what all PhD interview contains.
Dr. Paresh B. Gujarati.
'I'mprovement always begins with 'I'.