good afternoon,
hope you are doing good, as per your query you complete your 10th board and you want to do 11th class from CBSE. It is not illegal you can easily do you 11th class from CBSE you just need to do registration from cbse website and you can continue your 12th board from CBSE also.
hope it will bw halpful for you
All the best!
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile