Hello aspirant, 

If you are from general category then you wont be able to qualify . But if u r from sc or st then you will be promoted to jee advance. A candidate need to have 75% or more marks or be in the top 20 percentile in Class 12 to get admission in IITs or NITs through JEE MAIN. This is the relation by which top students get into IITs and NITs. But you can know find out your admission in college based on JEE MAIN here

Hope you understand, 
Thank you 

No u r not eligible for advance with 71% in cbse board.

U need atleas 75%