hi,

see to get admission in any of the iits in bachelor of architecture course, students have to appear in jee main exam, then jee advance test. you are eligible to appear in jee advance test only you get the  qualifying cutoff score in jee main exam. after that you qualify in jee advance test , students who wish to study b.arch course need to appear for JEE Advanced Architecture Aptitude Test (AAT) .

Now that you know about iits b.arch admission process follow our  article at below link to know in details:

https://engineering.careers360.com/articles/jee-advanced-aat