The CBSE has made it compulsory for candidates to submit their Aadhaar number to register for the board exams of Class 9 and 11 from 2017-18.

All CBSE-affiliated schools have been notified to register their students from Class 9 and 11 on the official website of the CBSE Board by submitting the necessary supporting documents and subject-related details. According to CBSE, If the Aadhaar number is not available, the Aadhaar enrolment number can be provided for the registration.
This is for the first time that the CBSE has made it mandatory to submit Aadhaar details to register for the examination.
OneIndia News