Hello Aspirant ,

No , you do not need dummy school with coaching classes to prepare for NDA examination , a student can easily clear NDA exam without any coaching classes if he prepares with hard and smart work but you should always look for guidance from someone like teacher , senior etc but if you think it is really hard for you to prepare for NDA you should look for coaching in your locality and there is no need of dummy school.

Giving 2 to 3 hours daily can easily help you clear NDA exam .

Hope this helps.