hi,

see it is not applicable to do your phd course like that you have done your 50% in iit, then you do 50% from nits, if you have enrolled in phd course either in iits or nits you need to complete it from that particular institute only. if you are from engineering background, you need gate score to apply for phd in iits, however students who have passed mtech from nits can apply iits for phd with out having gate score.