🚀 ISRO and DRDO - India's Premier Space and Defence Research Organisations
ISRO and DRDO Recruitment 2026 - Scientist, Engineer and Technical Assistant - Mock Tests, Syllabus and Exam Pattern
Complete guide for ISRO and DRDO recruitment across all major posts. ISRO ICRB recruits Scientist/Engineer SC through its own CBT (80 technical + 15 aptitude questions, 50% written + 50% interview). DRDO CEPTAM recruits Senior Technical Assistant B and Technician A through a two-tier CBT with no separate interview. DRDO RAC recruits Scientist B through written test and interview. All three are prestigious central government science and defence R and D career paths. Free mock tests, organisation-wise exam patterns, discipline-wise syllabus, cut-offs and expert tips - all in one place.
ISRO - 95 Qs, 50-50 Merit
CEPTAM - Two-tier CBT
RAC - Scientist B
No GATE Required for ISRO
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ISRO
Own CBT, No GATE Needed
50-50
ISRO Written + Interview
764
DRDO CEPTAM 11 Vacancies
L-10
Scientist Pay Level
65%
Min. Marks for ISRO
🗺️ Three Distinct Recruitment Routes - Understand Which One Applies to You
🚀 ISRO ICRB - Scientist/Engineer SC
For BE/BTech graduates (65% min). Own CBT exam - no GATE needed. 80 technical + 15 aptitude questions. 50% written + 50% interview. Pay Level 10.
🛡️ DRDO CEPTAM - STA-B and Technician A
For Diploma holders (STA-B) and ITI/Class 10+2 (Tech-A). Two-tier CBT - no interview. Tier II is decisive for STA-B. Pay Level 6.
🔬 DRDO RAC - Scientist B
For BE/BTech/ME/MTech graduates. Written test + interview. Sometimes GATE score used for shortlisting. Pay Level 10. Separate RAC notification.
📋 Table of Contents
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🎯 Practice Mock Tests - Subject-wise
ISRO and DRDO technical exams are at GATE-equivalent depth. The aptitude and general awareness sections in these exams are also important. Practice below.
🚀 ISRO and DRDO technical exams are at GATE-equivalent depth: 80% of the ISRO Scientist/Engineer written exam (Part A) is from your engineering discipline at GATE level. DRDO CEPTAM Tier II is discipline-specific at diploma level. DRDO RAC Scientist B technical section is at GATE/post-graduation level. GATE preparation is the most efficient foundation for all three routes.
⚖️ ISRO vs DRDO - All Recruitment Routes Compared
Choose your route based on qualification level and career goal. ISRO and DRDO RAC are for graduate engineers; DRDO CEPTAM is for diploma holders.
🚀 ISRO ICRB - Scientist/Engineer SC Exam Pattern
ISRO's own ICRB (Centralized Recruitment Board) exam - no GATE needed. 65% minimum in BE/BTech mandatory. Interview carries 50% weight in final selection.
📄 ISRO Written Exam
95 questions total - 2 hours - 1/3 negative marking - objective MCQ
1/3 negative marking per wrong answer. 2 hours for 95 questions. Disciplines: Electronics, Mechanical, Computer Science (main ICRB cycles); also Civil, Electrical and others in specific notifications. Marks: question-wise marks not fixed at same value - check specific notification.
🚀 ISRO Key Facts
- Department of Space - directly under Prime Minister's Office
- Core work: Satellite design, launch vehicles (GSLV, PSLV, LVM3), space science, remote sensing
- Main centres: VSSC (Thiruvananthapuram), ISAC (Bengaluru), SAC (Ahmedabad), URSC, NRSC
- 320 vacancies in 2025 ICRB cycle (Electronics, Mechanical, CSE)
- Also separate notifications from individual centres (SAC, VSSC, etc.)
- Minimum 65% marks or CGPA 6.84/10 in BE/BTech
- Age limit: 35 years (with standard relaxations)
- Interview carries 50% weight - equal to written test
- Entry Pay: Level 10 - Rs.56,100 to Rs.1,77,500
💡 ISRO technical questions are at GATE difficulty level and sometimes harder in specific topics like Space Applications and Satellite Technology. Prepare using GATE material + ISRO previous year papers.
🛡️ DRDO CEPTAM - STA-B and Technician A Exam Pattern
DRDO CEPTAM 11 (2026): 764 vacancies - 561 STA-B + 203 Tech-A. Tier I held 23 March 2026; Tier II 15 June 2026. No interview for either post.
📄 CEPTAM STA-B - Tier I (Screening)
150 questions - 150 marks - -0.25 negative marking - CBT mode
-0.25 per wrong answer. Minimum qualifying: 40% (UR/OBC/EWS) | 35% (SC/ST). Shortlisting ratio 1:8 for Tier II. Tier I marks count in merit (not purely screening - marks affect Tier I rank for shortlisting). CBT mode online.
📄 CEPTAM STA-B - Tier II (Decisive)
150 questions - 100 marks - -0.5 negative marking - 90 minutes - CBT mode
Final selection is based entirely on Tier II score. No interview for STA-B. Disciplines for STA-B include: Electronics, Mechanical, Electrical, Computer Science, IT, Civil, Chemical, Instrumentation and others based on notification.
🛡️ DRDO CEPTAM Key Facts
- DRDO under Ministry of Defence - 50+ labs across India
- CEPTAM 11: 764 vacancies (561 STA-B + 203 Tech-A)
- Tier I exam: 23 March 2026 (completed)
- Tier II exam: 15 June 2026
- No interview for STA-B or Tech-A - purely exam-based
- STA-B requires 3-year Diploma in relevant engineering discipline
- STA-B Pay: Level 6 - Rs.35,400 to Rs.1,12,400
- DRDO labs: DRDL, DEAL, CAIR, DMRL, SAG, TBRL, IRDE, and 40+ others
- Tier II -0.5 negative marking is significantly stricter than Tier I's -0.25
🔬 DRDO RAC - Scientist B Recruitment
RAC (Recruitment and Assessment Centre) conducts DRDO Scientist B recruitment for graduate engineers. Separate from CEPTAM - targets higher qualification level.
📄 DRDO Scientist B - RAC Selection
Written test + Interview - exact pattern varies by notification
RAC notifications are released based on specific DRDO lab requirements - not on a fixed cycle. Monitor drdo.gov.in and racdrdo.ac.in regularly. Some RAC notifications specify GATE score as shortlisting criterion - check each notification individually.
🔬 DRDO RAC Key Facts
- RAC = Recruitment and Assessment Centre (also referred to as Recruitment and Assessment Board)
- Recruits directly for specific DRDO labs and projects
- Scientist B is entry-level - equivalent to ISRO Scientist/Engineer SC
- Disciplines vary by notification: Electronics, CS, Mechanical, Electrical, Physics, Chemistry, Life Sciences and more
- Pay Level 10: Rs.56,100 - Rs.1,77,500 (same as ISRO entry)
- More R and D focused than administrative - DRDO labs work on missile technology, radar, sonar, explosives, materials science
- Separate from CEPTAM - do not confuse
- Sometimes GATE 2023/2024 score used for initial shortlisting - check specific notification
✅ Eligibility Criteria
Qualification level is the key differentiator - CEPTAM for diploma holders, ISRO ICRB and DRDO RAC for degree holders
⚙️ Technical Syllabus - Discipline-wise
ISRO and DRDO technical questions are at GATE-equivalent depth. Build from GATE study material for your discipline. DRDO CEPTAM Tier II is at diploma/Class 10+2 engineering level.
📡 Electronics and Communication Engineering
Primary discipline for ISRO ICRB; also DRDO labs (DEAL, SAMEER, IRDE)
- Engineering Mathematics - Linear Algebra, Probability, Complex Analysis
- Electronic Devices - Semiconductor devices, BJT, FET, op-amps
- Analog and Digital Circuits - Amplifiers, logic gates, sequential circuits
- Signals and Systems - Fourier, Laplace, Z-transform
- Control Systems - Transfer function, stability, Bode plot
- Communications - AM, FM, digital modulation, satellite communication
- Electromagnetic Theory and Antenna systems
- Microprocessors and Embedded Systems
- VLSI, Microwave Engineering, RF Systems
- ISRO-specific: Satellite communication systems, telemetry, telecommand, ground station operations
🔧 Mechanical Engineering
Core for ISRO (launch vehicles, propulsion); DRDO (DRDL missiles, GTRE jet engines)
- Engineering Mechanics and Strength of Materials
- Theory of Machines, Vibrations and Fatigue
- Fluid Mechanics and Fluid Machinery
- Thermodynamics, Heat and Mass Transfer
- Manufacturing Engineering - Machining, Welding, Forming
- Design of Machine Elements - Failure theories, Stress analysis
- Refrigeration and Air Conditioning
- Industrial Engineering - Operations Research, Quality Control
- ISRO-specific: Rocket propulsion, nozzle design, composite materials, launch vehicle structures
- DRDO-specific: Aerodynamics, explosives and warhead design basics, vehicle dynamics
💻 Computer Science
Increasingly important at ISRO (AI/ML for space) and DRDO (command systems, cyber)
- Programming - C, C++, Data Structures, Algorithms
- Theory of Computation - Automata, Languages
- Operating Systems - Process, Memory, File Management
- Database Systems - SQL, ER Model, Normalisation
- Computer Networks - OSI, TCP/IP, Routing, Security
- Software Engineering - SDLC, Testing, UML
- Digital Logic and Computer Architecture
- Compiler Design - Parsing and Code Generation
- ISRO-specific: Real-time systems, embedded software, satellite data processing
- DRDO-specific: Cybersecurity, command and control systems, AI/ML for defence
💰 Salary, Pay Level and Career Growth
ISRO and DRDO Scientist/Engineer posts are Group A central government positions with structured career progression from Scientist SC to Scientist H (Distinguished Scientist)
🚀 ISRO Scientist Career Path
Scientist/Engineer SC (L10) → SD (L11) → SE (L12) → SF (L13) → SG (L13A) → SH (Outstanding Scientist) → Distinguished Scientist → Secretary DOS. Each promotion through Annual Performance Appraisal Reports (APARs) and Time-Based Assured Career Progression (TACP).
🛡️ DRDO Scientist Career Path
Scientist B (L10) → Scientist C (L11) → Scientist D (L12) → Scientist E (L13) → Scientist F/G (L13A) → Distinguished Scientist → Director General DRDO → Scientific Adviser to Raksha Mantri.
🎁 Benefits and Perks
- DA, HRA, TA as per central government norms
- CGHS Medical facilities for scientist and family
- Campus accommodation at ISRO/DRDO centres
- LTC (Leave Travel Concession)
- Research grants and project incentives
- International collaboration and deputation opportunities
- NPS pension scheme
📈 Previous Year Cut-off Marks
ISRO cut-offs are for written test shortlisting to interview. DRDO CEPTAM Tier I cut-offs for Tier II shortlisting.
🚀 ISRO ICRB Written Cut-offs (out of ~100)
| Discipline | GEN | OBC | SC/ST |
|---|---|---|---|
| Electronics | 58 - 68 | 50 - 60 | 42 - 52 |
| Mechanical | 55 - 65 | 48 - 58 | 40 - 50 |
| Computer Science | 60 - 70 | 52 - 62 | 44 - 54 |
Indicative estimates. ISRO does not publish official cut-off marks. Marks out of 95 (80 tech + 15 aptitude).
🛡️ DRDO CEPTAM Tier I Cut-offs (out of 150)
| Category | Qualifying Min | Shortlisting (Est.) |
|---|---|---|
| UR/OBC/EWS | 40% (60 marks) | 90 - 110 |
| SC/ST | 35% (52.5 marks) | 78 - 95 |
CEPTAM 11 Tier I held 23 March 2026. Tier II on 15 June 2026. Top 1:8 ratio shortlisted.
ℹ️ All cut-offs are indicative estimates from coaching institute analysis. Neither ISRO nor DRDO officially publishes cut-off marks for these examinations. ISRO written exam cut-offs depend heavily on the exam difficulty for that specific cycle. DRDO CEPTAM Tier II final merit is 100% based on Tier II score - Tier I only determines shortlisting.
💡 Expert Preparation Tips
From our faculty who have guided candidates to ISRO and DRDO Scientist and Technical Assistant selections
1
GATE preparation is the most efficient base for both ISRO and DRDO Scientist posts - but GATE score itself is not needed - ISRO Scientist/Engineer SC uses its own CBT (not GATE score), and DRDO CEPTAM also uses its own CBT. Neither requires a GATE scorecard. However, the technical questions in both exams are at GATE-equivalent depth and cover the same subjects. The most efficient preparation strategy is to prepare for GATE at full intensity (for the technical depth it forces) and then practice ISRO previous year papers specifically to calibrate difficulty and question style. ISRO papers are sometimes harder than GATE in specific topics like Satellite Communication and Space Applications. DRDO RAC sometimes uses GATE for initial shortlisting - check each specific RAC notification.
2
ISRO interview carries 50% weight - it is literally half the selection, not a formality - Most engineering recruitment exams (NIELIT, BEL, BHEL) weight the interview at 25-33%. ISRO uniquely gives the interview 50% weight - equal to the written test. A candidate who scores 70/95 in the written test but 85/100 in interview will outscore someone who scored 85/95 in written but only 60/100 in interview. ISRO interviews are deeply technical - the panel includes domain experts from your specific ISRO centre who will ask you about your final year project, core technical subjects, and space-specific applications of your discipline. Prepare your technical fundamentals thoroughly, understand ISRO's missions and projects, and practice explaining your final year project clearly at a conceptual level.
3
DRDO CEPTAM Tier II has -0.5 negative marking - twice as punishing as Tier I's -0.25 - Many CEPTAM candidates prepare for the same attempt strategy in Tier II as Tier I because both use the same format (CBT). This is a serious mistake. Tier I has -0.25 per wrong (1/4 of 1 mark); Tier II has -0.5 per wrong (1/2 of 1 mark, since each correct is 100/150 ≈ 0.67 marks). The expected value calculation changes significantly - you need to be much more confident before attempting in Tier II. Additionally, Tier II is discipline-specific technical content where casual guessing is even more unreliable. Target 90-100 confident correct answers in Tier II rather than attempting all 150 questions.
4
Study space and defence domain knowledge - ISRO and DRDO interviews expect this awareness - Both ISRO and DRDO recruit scientists and engineers who will work on actual space missions and defence projects. Their interview panels assess not just your technical textbook knowledge but your awareness of and enthusiasm for the specific domain. For ISRO: know ISRO's recent missions (Chandrayaan-3, Aditya-L1, INSAT, IRNSS/NavIC, Gaganyaan preparations), satellite types, launch vehicles (PSLV, GSLV Mark III/LVM3), ISRO centres and their specific functions. For DRDO: know India's defence systems (Akash, Brahmos, Tejas, Arjun tank), DRDO's key labs and their domains (DRDL for missiles, CAIR for AI, DMRL for materials, SAG for strategic systems), and recent DRDO technology achievements. This domain awareness is what separates technically similar candidates in interviews.
5
Individual centre notifications from ISRO are separate from ICRB - watch for both - ISRO recruits through two parallel channels: the centralised ICRB notifications (for mass recruitment of Scientist/Engineer SC across disciplines) and individual centre-specific notifications from SAC (Space Applications Centre, Ahmedabad), VSSC (Vikram Sarabhai Space Centre, Thiruvananthapuram), ISAC, URSC, NRSC and others. Individual centre notifications sometimes have different eligibility requirements, different disciplines, and even different selection processes (some use GATE scores). Monitor both isro.gov.in and the specific centre websites. Missing an individual centre notification because you only checked ICRB means missing potential opportunities - especially for specialised positions in payload development, remote sensing, or space science.
6
Security clearance is a post-selection requirement - be aware of its implications - Both ISRO and DRDO require security clearance for their scientists and technical staff since they work on classified projects, defence technologies and space assets. The security clearance process involves background verification of the candidate, their family members, and their residential history. This process takes 3-12 months after selection. Candidates with foreign nationality family members, international financial connections, or prolonged foreign residence may face delays or clearance complications. This does not affect the selection itself but affects joining timelines. Candidates should be transparent in all forms and be prepared for the verification process. Security clearance is standard for all government defence and strategic organisations and is not specific to criminal background.
❓ Frequently Asked Questions - ISRO and DRDO Recruitment 2026
Most searched questions about ISRO and DRDO scientist and technical recruitment answered by our experts
GATE score is NOT required for ISRO ICRB or DRDO CEPTAM - both conduct their own examinations. DRDO RAC sometimes uses GATE scores for initial shortlisting in specific Scientist B notifications - check each RAC notification individually. The three routes differ fundamentally in qualification and career level: ISRO ICRB recruits Scientist/Engineer SC for graduate engineers (BE/BTech, 65% minimum) through its own CBT plus interview, with the interview carrying 50% weight. DRDO CEPTAM recruits STA-B for diploma holders and Technician A for ITI/Class 10+2 candidates through a two-tier CBT with no interview. DRDO RAC recruits Scientist B for graduate and postgraduate engineers through written test and interview - similar level to ISRO SC but for DRDO. ISRO SC and DRDO Scientist B are both Pay Level 10; DRDO CEPTAM STA-B is Pay Level 6.
ISRO ICRB conducts Scientist/Engineer SC recruitment approximately once a year but not on a perfectly fixed schedule. Recent major cycles include 2023 and 2025 (320 vacancies in Electronics, Mechanical and CSE). Additionally, individual ISRO centres (SAC, VSSC, ISAC, URSC, NRSC etc.) release separate notifications throughout the year for specific positions. So while the main ICRB centralised notification may come once a year, centre-specific notifications can appear at any time. Monitor isro.gov.in (main ICRB) and individual centre websites. ISRO also recruits for research fellowships (JRF/SRF) and project positions which are not the same as the permanent Scientist/Engineer posts. Always check whether a notification is for permanent Scientist/Engineer posts or for contractual/fellowship positions.
Both are prestigious central government R and D careers but with distinct cultures. ISRO has a highly mission-driven culture focused on space exploration, satellite development, and launch vehicle technology. Projects are high-profile, timelines are defined by mission windows, and there is significant national visibility. ISRO has strong campus infrastructure at its major centres (Thiruvananthapuram, Bengaluru, Ahmedabad) with an academic-like environment. DRDO has a broader mandate covering all defence technologies - missiles, radar, sonar, explosives, materials, cyber, avionics, and more. DRDO has 50+ labs across India in diverse locations. Work is classified and less publicly visible than ISRO. DRDO is generally considered more secretive and security-conscious. For engineers interested specifically in space - choose ISRO. For those interested in defence and military technology with a broader range of disciplines - DRDO offers more variety. Both offer similar pay scales, career progression and service benefits.
No - diploma holders cannot apply for ISRO Scientist/Engineer SC or DRDO Scientist B/RAC positions. These require a BE/BTech degree with minimum 65% (ISRO) or 60%+ (DRDO RAC) marks. However, diploma holders have an excellent opportunity through DRDO CEPTAM - specifically the STA-B (Senior Technical Assistant B) post which requires a 3-year engineering diploma. DRDO CEPTAM STA-B positions offer Pay Level 6 (Rs.35,400+) with career advancement within the technical cadre. Diploma holders can also appear for DRDO Technician A posts. These CEPTAM positions allow diploma holders to work in DRDO labs on the same projects as Scientist B officers, in supporting technical roles. Some DRDO labs also recruit through apprentice schemes for diploma holders as an entry point before pursuing permanent positions.
ISRO ICRB major disciplines are Electronics/ECE (largest), Mechanical (second largest), and Computer Science. The 2025 ICRB notification had 320 vacancies predominantly in these three disciplines. Individual centre notifications add Architecture, Civil, Electrical and others. ISRO primarily needs Electronics engineers (for satellite systems, communication, power systems), Mechanical engineers (for launch vehicle structures, propulsion, spacecraft mechanisms) and CSE engineers (for ground systems, data processing, embedded software). DRDO CEPTAM STA-B vacancies span Electronics, Mechanical, Electrical, CSE, Civil, Chemical, Instrumentation and more - with Electronics and Mechanical typically having the most seats. DRDO RAC Scientist B covers an even wider range including Physics, Chemistry, Life Sciences, Materials Science, Naval Architecture, and Aeronautical in addition to engineering disciplines. The 764-vacancy CEPTAM 11 (2026) covered multiple technical disciplines across DRDO labs nationwide.
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Written and Reviewed by Our ISRO and DRDO Recruitment Expert Faculty
ISRO ICRB and DRDO CEPTAM Specialist | 10+ Years Space and Defence Engineering Exam Coaching
This page has been prepared by our senior engineering exam faculty with experience coaching ISRO Scientist/Engineer SC, DRDO CEPTAM STA-B and DRDO RAC Scientist B aspirants. All exam pattern details, recruitment route explanations, discipline-wise syllabus and preparation strategies are based on official ISRO ICRB and DRDO CEPTAM notifications. Monitor isro.gov.in, drdo.gov.in and racdrdo.ac.in for official notifications.
✅ ISRO ICRB Specialist ✅ DRDO CEPTAM and RAC Expert ✅ 400+ Scientists Selected
ISRO and DRDO Recruitment 2026 - Complete Guide: ICRB Scientist Engineer, CEPTAM STA-B, RAC Scientist B Syllabus and Free Mock Tests
India's two most prestigious science and defence research organisations - ISRO (Indian Space Research Organisation) under the Department of Space and DRDO (Defence Research and Development Organisation) under the Ministry of Defence - recruit engineers and scientists through three distinct pathways. ISRO ICRB (Centralized Recruitment Board) recruits Scientist/Engineer SC through its own CBT of 80 technical + 15 aptitude questions (95 total), 2 hours, 1/3 negative marking - no GATE score needed. Final merit is 50% written test + 50% interview. Minimum eligibility is BE/BTech with 65% or 6.84 CGPA. Entry pay is Level 10 (Rs.56,100+). The 2025 ICRB cycle had 320 vacancies in Electronics, Mechanical and CSE. DRDO CEPTAM recruits STA-B (diploma holders) and Technician A (ITI/Class 10+2) through a two-tier CBT with no interview - CEPTAM 11 (2026) had 764 vacancies (561 STA-B + 203 Tech-A); Tier I was held 23 March 2026; Tier II is on 15 June 2026. DRDO RAC recruits Scientist B for graduate/postgraduate engineers through written test and interview - sometimes using GATE score for shortlisting.
The ISRO written exam Part A (80 questions, 84% of total) is entirely from the chosen engineering discipline at GATE-equivalent depth - covering Engineering Mathematics, and all core subjects of Electronics/ECE, Mechanical, CSE or other disciplines. Part B (15 questions) tests Numerical Ability, Logical Reasoning and Abstract Reasoning. DRDO CEPTAM Tier I (150 questions, 150 marks, -0.25 negative) covers General Intelligence and Reasoning, General Science, General English and Quantitative Aptitude - same for all posts and serves as the screening test with top 1:8 ratio shortlisted. DRDO CEPTAM Tier II (150 questions, 100 marks, 90 minutes, -0.5 negative marking) is discipline-specific and entirely determines final selection. All three routes offer Pay Level 10 (Rs.56,100+) for graduate engineer / scientist posts and Level 6 (Rs.35,400+) for STA-B diploma posts.
Our free ISRO and DRDO mock tests cover all aptitude and general awareness subjects - General Intelligence and Reasoning, General Knowledge and Awareness (including space and defence domain GK), Numerical and Mathematical Ability, English Language, Physics and General Studies - available topic-wise at zero cost at StudiesToday.com. For technical discipline preparation, use GATE study material for your engineering branch as the primary resource.