Hello,

Are you enquiring for Officers Training Academy in regards to Combined Defense Exam conducted by UPSC, if yes then in order to apply for the same you need to pass graduation in any discipline from a recognized university, so first of all you need to complete your graduation in order to appear for OTA in CDS, when it comes to exam pattern for OTA it has mathematics and english which has 120 questions individually, each one consists of 100 marks and conducted for a duration of two hours, the syllabus is as follows-

English has synonyms ,antonyms ,Idioms & Phrases, comprehension, error spotting, cloze test, sentence completion, jumbled sentences

General Knowledge has general science, economics, history, polity, geography, art and culture, books and author

after being familiar with exam pattern and syllabus, it's important to choose study materials appropriate for the exam, you can refer Lucent's GK for static portion of General Knowledge and for dynamic portion you can read newspaper such as The Hindu/The Indian Express on a daily basis, for English refer Wren and Martin for grammar, Word Power Made Easy for vocabulary and SP Bakshi's Objective General English, you have to make a proper time table and assign required number of hours for each subject, go through previous year papers which you can access from our site by https://competition.careers360.com/articles/cds-question-papers and apply mock test to evaluate your preparation level.