IIT

There is no restriction about the distance degree for appearing in IIT JAM exam for M.Sc. Mathematics. So you can be eligible if meeting the below criteria. Educational qualification for M.Sc. Mathematics :
1. All candidates admitted through JAM should have a Bachelors degree.
2. In the qualifying degree, the aggregate marks or CGPA/CPI without rounding-off (taking into account all subjects, including languages and subsidiaries, all years combined) should be at least 55% or 5.5 out of 10 for General/OBC (NCL)/EWS category candidates, and 50% or 5.0 out of 10 for SC/ST and PwD category candidates.
3. Studied Mathematics in graduation for at least two years/four semesters.

For IIM, CAT score is important, and graduation needs only 50%, and for IIT:
Minimum 75% aggregate marks should have been secured in 12th standard (or equivalent) examination. The candidates should be within the top 20 category percentile of the qualifying examination. While calculating aggregate marks, the candidates should take into account scores of Physics, Chemistry, Mathematics, Language and any one other subject. The candidates will have to satisfy at least one of the following two criteria for admission to IITs: The candidate should have passed 10+2 or equivalent examination with an aggregate of at least 75% marks. For SC/ ST and BC candidates, there is a relaxation of 10% as they need the aggregate of minimum 65% marks. HOPE THIS HELPS, WISH YOU LUCK FOR YOUR FUTURE ENDEAVORS!