GATE 2023 CS question paper PDF and answer key

The official GATE 2023 Computer Science & Information Technology paper, organised by IIT Kanpur: 65 questions for 100 marks in 3 hours. Download the official question paper and answer key as PDFs. Below is how the marks were split by topic, the complete official answer key and 5 questions solved step by step.

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Question paper (PDF)Official answer key (PDF)

Source: the official paper and answer key published by IIT Kanpur for GATE 2023 (official GATE site). Spotted a mistake? Email team@lemyte.com.

General Aptitude: 10 · 15 marks
Computer Science & Information Technology: 55 · 85 marks
MCQ / MSQ / NAT: 34 / 15 / 16
Marks to all: None

Where the marks were

GATE 2023 CS topic-wise marks

Computer Science & Information Technology questions only; General Aptitude adds 15 marks on top. The top three topics carried 30 of the 85 subject marks.

Topic	Questions	Marks
Discrete Mathematics	7	11
Operating System	7	10
Theory of Computation	6	9
Programming and Data Structures	6	9
Computer Organization and Architecture	5	9
Computer Networks	5	8
Compiler Design	4	7
Algorithms	4	6
Digital Logic	4	6
Databases	3	5
Calculus	2	2
Probability and Statistics	1	2
Linear Algebra	1	1

Free solved questions

5 solved questions from GATE 2023 CS

Question text and figures as in the official paper, the answer from the official key, and a worked solution. The other 60 solutions are in your report after you take the paper.

Q4 · General Aptitude · MCQ · 1 mark

A survey for a certain year found that 90% of pregnant women received medical care at least once before giving birth. Of these women, 60% received medical care from doctors, while 40% received medical care from other healthcare providers.

Given this information, which one of the following statements can be inferred with certainty?

(A)
More than half of the pregnant women received medical care at least once from a doctor.
(B)
Less than half of the pregnant women received medical care at least once from a doctor.
(C)
More than half of the pregnant women received medical care at most once from a doctor.
(D)
Less than half of the pregnant women received medical care at most once from a doctor.

Answer (official key): A

Solution

Out of all pregnant women, 90% received medical care at least once. Of those, 60% received care from doctors. So the percentage who received care from doctors is

0.9 \times 0.6 = 0.54 = 54\%.

That is more than half.

Therefore, the correct answer is Option A.

Q6 · General Aptitude · MCQ · 2 marks

Which one of the following sentence sequences creates a coherent narrative?

(i) Once on the terrace, on her way to her small room in the corner, she notices the man right away.
(ii) She begins to pant by the time she has climbed all the stairs.
(iii) Mina has bought vegetables and rice at the market, so her bags are heavy.
(iv) He was leaning against the parapet, watching the traffic below.

(A)
(i), (ii), (iv), (iii)
(B)
(ii), (iii), (i), (iv)
(C)
(iv), (ii), (i), (iii)
(D)
(iii), (ii), (i), (iv)

Answer (official key): D

Solution

A coherent sequence is:

first, Mina has heavy bags
then she climbs the stairs and pants
once on the terrace, she notices the man
finally, the man is described

So the coherent order is (iii), (ii), (i), (iv).

Therefore, the correct answer is Option D.

Q35 · Computer Organization and Architecture · Numerical · 1 mark

Consider a 3-stage pipelined processor having a delay of 10 ns (nanoseconds), 20 ns, and 14 ns, for the first, second, and the third stages, respectively. Assume that there is no other delay and the processor does not suffer from any pipeline hazards. Also assume that one instruction is fetched every cycle.

The total execution time for executing 100 instructions on this processor is __________ ns.

Answer (official key): 2040

Solution

The pipeline clock period is determined by the slowest stage:

\max(10,20,14)=20 \text{ ns}.

For a 3-stage pipeline executing 100 instructions, total cycles required are:

k+n-1 = 3+100-1 = 102.

Hence total execution time is

102 \times 20 = 2040 \text{ ns}.

Therefore, the answer is 2040.

Q39 · Compiler Design · MCQ · 2 marks

Consider the control flow graph shown.

Control Flow Graph for Q37

Which one of the following choices correctly lists the set of live variables at the exit point of each basic block?

(A)
B1: {}, B2: {a}, B3: {a}, B4: {a}
(B)
B1: {i, j}, B2: {a}, B3: {a}, B4: {i}
(C)
B1: {a, i, j}, B2: {a, i, j}, B3: {a, i}, B4: {a}
(D)
B1: {a, i, j}, B2: {a, j}, B3: {a, j}, B4: {a, i, j}

Answer (official key): D

Solution

This is a control-flow / liveness-analysis question. The official answer key marks Option D as correct. A full backward data-flow derivation can be added later if you want the final polished explanation.

Q41 · Computer Networks · MSQ · 2 marks

Suppose you are asked to design a new reliable byte-stream transport protocol like TCP. This protocol, named myTCP, runs over a 100 Mbps network with Round Trip Time of 150 milliseconds and the maximum segment lifetime of 2 minutes.

Which of the following is/are valid lengths of the Sequence Number field in the myTCP header?

(A)
30 bits
(B)
32 bits
(C)
34 bits
(D)
36 bits

Answer (official key): B, C, D

Solution

At 100 Mbps, the sender can inject

100 \times 10^6 \text{ bits/sec} = 12.5 \times 10^6 \text{ bytes/sec}.

Over a maximum segment lifetime of 120 seconds, this is

12.5 \times 10^6 \times 120 = 1.5 \times 10^9 \text{ bytes}.

So the sequence number space must exceed this order of magnitude. Since

2^{30} \approx 1.07 \times 10^9

is too small, 30 bits is invalid, while 32 bits and above are valid.

Therefore, the correct answers are B, C, and D.

The other 60 questions are solved in your report when you take GATE 2023 CS as a 3-hour test.

Take GATE 2023 CS as a test

Official answer key

GATE 2023 CS answer key

All 65 answers from the official key. Numerical answers are ranges; “or” means the key accepts either answer.

Download the official GATE 2023 CS answer key (PDF)

Q	Topic	Type	Marks	Answer
1	Spatial Aptitude	MCQ	1	C
2	Quantitative Aptitude	MCQ	1	A
3	Verbal Aptitude	MCQ	1	B
4	Analytical Aptitude	MCQ	1	A
5	Verbal Aptitude	MCQ	1	A
6	Verbal Aptitude	MCQ	2	D
7	Analytical Aptitude	MCQ	2	D
8	Analytical Aptitude	MCQ	2	B
9	Quantitative Aptitude	MCQ	2	C
10	Spatial Aptitude	MCQ	2	A
11	Theory of Computation	MCQ	1	C
12	Discrete Mathematics	MCQ	1	A
13	Computer Networks	MCQ	1	B
14	Programming and Data Structures	MCQ	1	B
15	Programming and Data Structures	MCQ	1	D
16	Algorithms	MCQ	1	C
17	Linear Algebra	MCQ	1	B
18	Compiler Design	MCQ	1	B
19	Theory of Computation	MCQ	1	C
20	Databases	MCQ	1	A
21	Computer Networks	MSQ	1	A, C
22	Operating System	MSQ	1	C, D
23	Digital Logic	MCQ	1	B
24	Discrete Mathematics	MSQ	1	B, C
25	Theory of Computation	MSQ	1	A, C, D
26	Algorithms	MSQ	1	A, C
27	Calculus	MSQ	1	B, D
28	Operating System	MSQ	1	B, C, D
29	Operating System	MSQ	1	C, D
30	Discrete Mathematics	Numerical	1	2
31	Digital Logic	Numerical	1	110
32	Operating System	Numerical	1	10.2
33	Calculus	Numerical	1	0
34	Programming and Data Structures	Numerical	1	7
35	Computer Organization and Architecture	Numerical	1	2040
36	Operating System	MCQ	2	C
37	Theory of Computation	MCQ	2	A
38	Theory of Computation	MCQ	2	B
39	Compiler Design	MCQ	2	D
40	Compiler Design	MCQ	2	A
41	Computer Networks	MSQ	2	B, C, D
42	Discrete Mathematics	MSQ	2	B, C, D
43	Digital Logic	MCQ	2	C
44	Computer Organization and Architecture	MCQ	2	C
45	Discrete Mathematics	MCQ	2	D
46	Computer Organization and Architecture	MCQ	2	B
47	Programming and Data Structures	MCQ	2	C
48	Computer Organization and Architecture	MCQ	2	C
49	Digital Logic	MCQ	2	A
50	Programming and Data Structures	MCQ	2	B
51	Probability and Statistics	MSQ	2	C, D
52	Computer Networks	Numerical	2	3
53	Discrete Mathematics	MSQ	2	A, D
54	Algorithms	MSQ	2	A, D
55	Theory of Computation	Numerical	2	4
56	Algorithms	Numerical	2	5040
57	Programming and Data Structures	Numerical	2	8
58	Computer Organization and Architecture	Numerical	2	19
59	Operating System	Numerical	2	5
60	Compiler Design	Numerical	2	2.374 to 2.376
61	Databases	Numerical	2	6
62	Discrete Mathematics	MSQ	2	A, B
63	Operating System	Numerical	2	4096
64	Databases	Numerical	2	2
65	Computer Networks	MSQ	2	C, D

Questions about GATE 2023 CS

How many questions are in the GATE 2023 CS paper?

65 questions for 100 marks: 10 General Aptitude questions worth 15 marks and 55 Computer Science & Information Technology questions worth 85 marks. By type, there were 34 MCQs, 15 MSQs, 16 numerical answer (NAT) questions. The paper lasted 3 hours.

Is there negative marking in GATE 2023 CS?

Yes, for MCQs only. A wrong MCQ answer costs one-third of its marks (−⅓ for a 1-mark question, −⅔ for a 2-mark question). MSQ and numerical (NAT) questions have no negative marking, and an MSQ earns marks only when every correct option is chosen.

Which topics carried the most marks in GATE 2023 CS?

Outside General Aptitude, the biggest topics were Discrete Mathematics (11 marks), Operating System (10 marks), Theory of Computation (9 marks). The full topic-wise split is in the table on this page.

Were any GATE 2023 CS questions awarded marks to all?

No. Every question was graded with the answer in the official key.

Where does this GATE 2023 CS answer key come from?

From the official answer key published by IIT Kanpur, which organised GATE 2023. Range answers for numerical questions and questions with more than one accepted answer are kept exactly as the key gives them.

GATE 2023 CS question paper PDF and answer key

GATE 2023 CS topic-wise marks

5 solved questions from GATE 2023 CS

GATE 2023 CS answer key

Questions about GATE 2023 CS

How many questions are in the GATE 2023 CS paper?

Is there negative marking in GATE 2023 CS?

Which topics carried the most marks in GATE 2023 CS?

Were any GATE 2023 CS questions awarded marks to all?

Where does this GATE 2023 CS answer key come from?

More GATE papers