Hi there,
Hope you are doing well.
Since you are currently in class 11th.
So, you are currently not eligible for any NDA or IAS Exam.
For NDA, the minimum requirement is 12th Studying with an age between 16.5-19.5.
For IAS i.e. UPSC, you should have a graduation degree with an upper age limit of 32 for General, 35 for OBC and 37 for SC/ST Category students.

Hope it would help.
Thank You.