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Combined Defense Service (CDS).


CDS stands for Combined Defence Services, candidates who wants to be a part of Indian Military Academy, Officers Training Academy, Indian Naval Academy and Indian Air Force Academy have to apply for Combined Defence Services Examination. CDS exam is conducted twice in a year by UPSC (Union Public Services Conducted), candidates who have cleared CDS written exam will be called for interview by Service Selection Board (SSB) and the successful candidates will be appointed with respective training academies.

CDS Exam Pattern:

The competitive exam comprises of two stages viz:

  • Written Exam

  • Interview for intelligence and personality test


The subjects of CDS written exam, the time allowed and the maximum marks allotted to each subject is tabulated below: 

For Indian Military, Indian Naval and Air Force Academy






For Officers Training Academy

CDS Exam Pattern in Detail:

Mode of Exam: 

Offline i.e. candidates will be allocated an OMR sheet wherein they must color the appropriate response. 

Type of Questions: 

Objective Type i.e. each question will have four options. A candidate must choose the most appropriate response.

Medium of Exam: 

Bilingual in Hindi as well as English

Standard of Questions: 

Given below is the expected standard of each section in CDS Exam:

  • The standard of the papers in Elementary Mathematics will be of Matriculation level. The standard of papers in other subjects will approximately be such as may be expected of a graduate of an Indian University.

  • English: The question paper will be designed to test the candidates’ understanding of English and workmanlike use of words.

  • General Knowledge: General Knowledge including knowledge of current events and of such matters of everyday observation and experience in their scientific aspects as may be expected of an educated person who has not made a special study of any scientific subject. The paper will also include questions on History of India and Geography of a nature which candidate should be able to answer without special study.


Other Facts:

  • Candidates must write the papers in their own hand. In no circumstances will they be allowed the help of a scribe to write answers for them.

  • The Commission has the discretion to fix qualifying marks in any or all the subjects of the examination.

  • The candidates are not permitted to use a calculator for answering objective type papers (Test Booklets). They should not, therefore, bring the same inside the Examination Hall.

  • Those who qualify in the written test are called for the second stage i.e., Intelligence and Personality Test. 

  • The maximum marks allotted to the written examination and to the interviews will be equal for each course i.e. the maximum marks allotted to the written examination and to the interviews will be 300, 300, 300 and 200 each for admission to the Indian Military Academy, Indian Naval Academy, Air Force Academy and Officers’ Training Academy respectively.


CDS Marking Scheme:

Negative marking is applicable for every wrong marked answer. In CDS paper, each question carries 4 options and out of which only 1 option is correct. For each incorrect answer, 1/3 of the marks will be deducted. More than one option marked is treated as incorrect. However, if a question is left unanswered there will be no negative marking.

The following table explains the detailed marking scheme of the exam.














The following table shows Marking scheme for OTA (Officers Training Academy):

Distribution of Questions:

Equal weightage is given to all the sections- GK, Mathematics and English.



The selection of the candidates is on the basis of marks scored in the interviews. Total marks for interview for Indian Military Academy, Naval Academy, and Air Force Academy is 300 marks, whereas 200 marks are allotted for interview for OTA.


CDS Intelligence and Personality Test Pattern:

SSB interview will be the 2nd part of the selection procedure. SSB Interview will contain two stages i.e. Stage 1 and Stage 2. Candidates qualify the stage 1 exam will be called for stage 2.

Stage 1: It is an OIR (Officer Intelligence Rating) Test which contains Picture Perception and Description Test (PP& DT). Candidates will be shortlisted as per their performance in OIR test and PP and DT.

Stage 2: Candidates passing stage 1 will be called for this stage. This part consists of Group Testing Officer Tasks, Interview, Conference and Psychology Test. These tests are organized in four days.

CDS Syllabus for English:

English question paper will be designed to test the candidates' understanding of English language. As per previous year analysis, following are the important topics asked in English paper.


Recommended Books :

CDS Exam Preparation English books are mentioned below:


CDS Syllabus for General Knowledge:

For GK paper, candidates can cover the following topics:

  • Latest Current Affairs

  • Indian Constitution

  • Indian History

  • Indian Economy

  • Indian Geography

  • Indian Politics

  • Indian Navy & Military

  • Religions

  • Books & Authors

  • Sports, Awards, etc


As per previous year analysis following are the important topics for GK paper:


Preparation Books:

CDS does not have a well-structured syllabus for General Knowledge so a thorough study is needed for GK paper. The following books can be followed to study for GK paper.






CDS Syllabus for Elementary Mathematics:

Mathematics paper covers topics from diverse topics. Following are the topic covered in CDS Mathematics paper.

  • Arithmetic

  • Number System

  • Elementary Number Theory

  • Algebra

  • Trigonometry

  • Geometry

  • Mensuration

In the following table, previous year paper analysis of mathematics paper is mentioned.

Recommended Books: 

Candidates can follow the NCERT books to clear the basics but for competitive exam level mathematics, you need a book on quantitative aptitude to learn and practice advanced concepts.

List of Mathematics books is as follows:

Instructions to Fill CDS Answer Sheet:

Candidates are advised to follow the instructions to fill OMR sheet very carefully as the answer sheets are to be evaluated on the machine and any violation of these instructions may result in the reduction of scores. Before marking responses on the Answer Sheet, aspirants have to fill in various particulars in it.

After receiving CDS Answer Sheet, candidates have to check that it is numbered at the bottom. If it is un-numbered, it has to be replaced by a numbered one. The top of the answer sheet will have the particulars shown in the figure below.


The following points should be kept in mind while filling CDS answer sheet:

  • Write with black ball pen only.

  • The test Booklet Series will be indicated by Alphabets A, B, C or D at the top right-hand corner of the Booklet.

  • Find out the appropriate subject code from the test booklet. Thereafter, encode the test booklet series, subject code and the roll number by using black pen.

  • Write and encode test booklet series after receiving the Test Booklet. For example, for English paper of ‘A’ Test Booklet Series you have to encode the subject code, which is 01 as shown below:

  • In the next step, you have to encode the Roll No. An example to encode the Roll Number is shown below.

  • Candidates have to make sure that they have carefully encoded their subject Test Booklet series and Roll Number.

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