Combined Defence Service Examination is conducted twice every year by Union Public Service Commission (UPSC).

As you want to know the important dates of the examination here I am telling you the same:

Date of Notification: 19.07.2014
Start of receipt of applications: 19.07.2014
Last date for receipt of applications: 18.08.2014
Date of Examination: 26.10.2014
Results: First week of April 2015

Eligibility:
For Indian Military Academy and Officer's Training Academy:
The applicant should hold Degree of a recognized university or equivalent.

For Naval Academy:
You should have completed B.Sc (with Physics & Mathematics) or Bachelor of Engineering.

For Air Force Academy
The applicant should hold Degree of a recognised University (with Physics & Mathematics at 10+2 level) or Bachelor of Engineering.