CDS

You can not apply for NDA anymore as your age limit is over now. You can apply for CDS but you need to complete your degree for that. You can apply for CDS in your final year of graduation and thereafter till the age limit crosses. The age limits are different for different modules of CDS.
IMA- age limit: 19-24 years. Graduate in any stream.
OTA- 19-25 years, and graduate in any stream.
INA - 19-22 years. B.E/B.Tech or degree in Physics or Maths.
AFA - 19-23 years. BE/B.Tech or Graduate in any subject but must have Physics and Maths at 12th level.

Hi Shivam!
These are some good CDS coaching centre in Delhi:
1. Achiever's vision private limited
2. Cambridge Institute of Professional Studies
3. The Exam Guru
4. Brilliant Academy of Learning.

Yes, you can apply for only CDS exam for IMA and Officer Training. You cannot apply for Indian Naval Academy (it needs a degree in engineering or B.Sc with physics and maths) and Air Force (it needs a degree from a recognised university (with physics and maths at +2 Level or B.E/B.Tech).

CDS is a Combined Defence Services Examination conducted by UPSC Union Public Service Commission twice a year probably in February and in October/November. It is a written examination consisting of three papers Maths Gk and English it is a multiple choices question paper. Paper does have negative marking. For each correct answer you will get 0.8 marks while for each wrong answer 0.3 marks will be deducted.

Hello Abhishek,
M.Sc is a master course so, the syllabus is big. If you can handle it then you can go for it. There are many colleges like IGNOU etc. which give distance education. You can join the coaching for the course you desire and go ahead.

After clearing CDS you can continue with your regular studies until you join training at IMA or OTS. Once you join training at IMA or OTS, you may continue with your studies on completion of your cadet training as external a candidate. You may not get any leave to appear for examination after training starts. You can appear in exams as external candidates during official breaks or holidays in training. Once, you get commission, you can take necessary approvals from your Commanding Officer to continue with further education.