Hi suman

Cbse and Rbse are both recognised boards. There is pattern is also close to similar. But according to me 11 and 12th should be done from same board. So if your son has done his 11th from rbse then he should do his 12th from the same board. Also if want to do it from cbse board then also it possible as the school will demand his passed certificate for 11th class and 10th certificat also for the birth proof. I hope you this helped you.