Bangladesh Bank — Assistant Director (ICT) — Exam: 07.02.2025 (DU) | প্রশ্ন ও সমাধান

Question 1Programming

Find Output:

int fun(int *p) {
    *p = *p + 10;
    return *p;
}
int main() {
    int x = 5;
    cout << fun(&x);
    return 0;
}

a)15
b)10
c)25
d)5

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Question 2Programming

Find Output:

int main() {
    int x=3, y=2;
    if (x==3)
        y=2;
    else
        y=3;
    cout<<x<<" "<<y<<endl;
    return 0;
}

a)3 3
b)3 2
c)2 3
d)3 1

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Question 3Digital Logic

Which one is a Universal logic gate?

a)NAND
b)AND
c)OR
d)NOT

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Question 4Data Structures

Which data structure is preferred for Priority Queue?

a)Heap Tree
b)Graph
c)Stack
d)Table

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Question 5Digital Logic

What is the work of a rectifier?

a)Converts DC to AC
b)Converts AC to DC
c)Stores Electrical Energy
d)Increases Voltage

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Question 6Database

A transfers a balance to B, but it does not reach B. Which property in ACID is responsible?

a)Atomicity
b)Consistency
c)Isolation
d)Durability

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Question 7Digital Logic

What is the 2's complement of (65)16 number?

a)10011011
b)10011010
c)00011011
d)10011100

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Question 8Digital Logic

What does inductance depend on?

a)Number of turns in the coil
b)Permeability of the core material
c)Cross-sectional area of the coil
d)All of the above (correct answer)

Answer and explanation

Correct answer: (d) All of the above

For a coil of N turns, cross-sectional area A and length l, the self-inductance is L = μN²A ÷ l, where μ = μ₀μᵣ is the permeability of the core material. So inductance:

rises with the square of the number of turns (double N → 4 × L);
rises in proportion to the core permeability (a magnetic core of relative permeability μᵣ multiplies L by μᵣ compared with the same coil in air);
rises in proportion to the cross-sectional area;
falls as the coil is made longer for the same number of turns.

Since (a), (b) and (c) are all genuine factors, "All of the above" is the complete answer.

Why the other options are wrong

(a) Number of turns in the coil: True (L ∝ N²), but it is only one of the factors.
(b) Permeability of the core material: True (L ∝ μ), but incomplete on its own.
(c) Cross-sectional area of the coil: True (L ∝ A), but incomplete on its own.

Tip: L = μN²A ÷ l: more turns, a magnetic core or a fatter coil raise L; a longer coil lowers it.

Source: What Is Inductance? – Keysight Oscilloscope Glossary

Question 9Digital Logic

Zener diode is a

a)Unidirectional
b)Bidirectional
c)Multidirectional
d)Tri-directional

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Question 10Programming

Which of the following does NOT achieve encapsulation?

a)Using private access specifier
b)Using classes in object-oriented programming
c)Using getter and setter methods
d)Using global variables (correct answer)

Answer and explanation

Correct answer: (d) Using global variables

Encapsulation keeps an object's data together with the methods that work on it, and hides that data so outside code can reach it only through those methods. A global variable does the opposite: it belongs to no object, and any function anywhere in the program can read or change it directly, with no checks. It gives neither bundling nor hiding.

Why the other options are wrong

(a) Using private access specifier: private limits a member to its own class. This is the main tool for data hiding.
(b) Using classes in object-oriented programming: a class puts fields and the methods that operate on them into one unit. That is the bundling half of encapsulation.
(c) Using getter and setter methods: they are the controlled path to private fields and can validate values (for example, reject a negative age). That is controlled access.

Tip: encapsulation = bundle + hide + controlled access. Anything that lets every part of the program change data freely breaks it. (Java has no true global variables; public static fields come closest and weaken encapsulation in the same way.)

Source: What Is an Object? (The Java Tutorials, Oracle)

Question 11Cyber Security

Which algorithm is used in email security?

a)AES
b)RSA
c)SHA
d)All of the above

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Question 12Digital Logic

In the given circuit, resistors of 10Ω, 20Ω, and 30Ω are connected in parallel, and a voltage source of 60V is applied across them. What is the equivalent current flowing from the voltage source?

a)8 A
b)9 A
c)11 A
d)12 A

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Question 13Operating Systems

A process needs I/O operations, it switches to

a)Ready
b)Running
c)Waiting (Blocked)
d)Terminated

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Question 14Web Technology

Which of the following is not a web server?

a)Apache Tomcat
b)PHP
c)Jetty
d)Tornado

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Question 15Database

Which clause is executed first in an SQL query?

a)WHERE
b)SELECT
c)FROM (correct answer)
d)ORDER BY

Answer and explanation

Correct answer: (c) FROM

A query is written SELECT … FROM … WHERE … ORDER BY, but it is evaluated in a different logical order. The engine first needs the rows to work on, so the FROM clause (with its joins) is processed first. Then WHERE filters rows, GROUP BY and HAVING form and filter groups, SELECT computes the output columns, and ORDER BY sorts the result:

FROM → WHERE → GROUP BY → HAVING → SELECT → DISTINCT → ORDER BY

This is the logical (binding) order. The optimiser may choose a different physical plan, but the result must be the same as if this order were followed.

Why the other options are wrong

(a) WHERE: It comes second; it filters the rows that FROM has produced, so it cannot run before them.
(b) SELECT: It is evaluated after WHERE, GROUP BY and HAVING. That is why a column alias defined in SELECT cannot be used in WHERE in standard SQL.
(d) ORDER BY: It comes last (only TOP/LIMIT/OFFSET follow it), which is why ORDER BY can use a SELECT alias.

Tip: Logical order starts with FROM and ends with ORDER BY, whatever the written order.

Sources: SELECT (Transact-SQL) - Microsoft Learn; SELECT - PostgreSQL Documentation; Problems with Column Aliases - MySQL 8.4 Reference Manual

Question 16Digital Logic

What should be true for a Zener Diode?

a)Reverse bias for amplifying
b)Operates in forward bias only
c)Works in reverse breakdown region
d)Used for rectification

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Question 17Database

Which of the following is a DML (Data Manipulation Language) command?

a)CREATE
b)DELETE
c)DROP
d)ALTER

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Question 18Data Structures

What is the worst case time complexity of inserting n elements into an empty linked list, if the linked list needs to be maintained in sorted order?

a)Θ(n)
b)Θ(n log n)
c)Θ(n²)
d)Θ(1)

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Question 19Data Structures

Which one of the following is an application of Stack Data Structure?

a)Managing function calls
b)The stock span problem
c)Arithmetic expression evaluation
d)All of the above

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Question 20Data Structures

What is the best way to implement priority queue?

a)Array
b)Linked List
c)Heap (correct answer)
d)Stack

Answer and explanation

Correct answer: (c) Heap

A priority queue must always hand out the item with the highest (or lowest) priority. A binary heap is a complete binary tree in which every parent's key is at least as extreme as its children's, so the top-priority item sits at the root.

Find max/min: read the root → O(1)
Insert: add at the last position and sift up along the height ⌊log₂ n⌋ → O(log n)
Delete max/min: move the last item to the root and sift down → O(log n)

Why the other options are wrong

(a) Array: Unsorted: insert O(1) but finding/removing the top item O(n). Sorted: removal is cheap but each insert costs O(n) shifting.
(b) Linked List: Same trade-off — one of insert or delete-top is O(n).
(d) Stack: LIFO — it returns the newest item, ignoring priority.

Tip: Priority queue ⇒ heap: O(log n) insert and delete, O(1) peek.

Sources: priority queue — NIST Dictionary of Algorithms and Data Structures; binary heap — NIST Dictionary of Algorithms and Data Structures

Question 21Cyber Security

What kind of encryption is used for securing emails in transit?

a)Symmetric Encryption
b)Asymmetric Encryption
c)TLS (Transport Layer Security)
d)Hashing

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Question 22Cyber Security

Digital Signature uses which algorithm?

a)AES
b)RSA (correct answer)
c)DES
d)Diffie-Hellman

Answer and explanation

Correct answer: (b) RSA

A digital signature needs an asymmetric algorithm: the signer uses a private key to generate the signature over a hash of the message, and anyone verifies it with the matching public key. RSA is one of the signature algorithms approved in the U.S. Digital Signature Standard (FIPS 186-5), alongside ECDSA and EdDSA.

Why the other options are wrong

(a) AES: a symmetric block cipher; both sides share the same key, so it cannot prove which of them produced a message.
(c) DES: also a symmetric block cipher, with the same shared-key limitation.
(d) Diffie-Hellman: a key-agreement (key-establishment) method used to set up a shared secret; it neither encrypts messages nor produces signatures.

Tip: Signature algorithms: RSA, DSA, ECDSA, EdDSA. Diffie–Hellman = key exchange.

Source: FIPS 186-5: Digital Signature Standard (DSS); RFC 4949: Internet Security Glossary, Version 2

Question 23Web Technology

What does HTTP Status Code 500 indicate?

a)Bad Request
b)Unauthorized Access
c)Internal Server Error
d)Not Found

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Question 24Database

Which one makes data access from a database faster?

a)Indexing
b)Normalization
c)Denormalization
d)All of the above

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Question 25Operating Systems

Priority Scheduling (Non-Preemptive) with No Arrival Time. Consider the following set of processes with their burst times and priorities:

Process	Burst Time (BT)	Priority
P1	10	3
P2	1	1
P3	2	4
P4	1	5
P5	5	2

Using Non-Preemptive Priority Scheduling (lower number = higher priority), what is the Average Turnaround Time (TAT)?

a)10
b)8.6
c)12
d)9.2

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Question 26Software Engineering

What is the major drawback of the waterfall model?

a)It is difficult to manage
b)It requires too many resources
c)It is inflexible and not suitable for changing requirements (correct answer)
d)It lacks proper documentation

Answer and explanation

Correct answer: (c) It is inflexible and not suitable for changing requirements

The waterfall model runs its phases strictly in order: one phase cannot start until the previous one is finished, and the requirements are expected to be completely specified at the end of the requirements phase. A requirement that changes later forces rework of design, code and tests already completed, and working software appears only near the end. That rigidity is its best-known drawback.

Why the other options are wrong

(a) It is difficult to manage: the opposite; clear phases, milestones and deliverables make it one of the easiest models to plan and track.
(b) It requires too many resources: resource use is not its defining problem; it needs no more staff than other models for the same scope.
(d) It lacks proper documentation: the waterfall model is document-driven; every phase ends with a document.

Tip: waterfall = stable, well-understood requirements; changing requirements → iterative or Agile models.

Source: SWEBOK Guide V4.0a (IEEE Computer Society)

Question 27Database

Which of the following is a command of Data Definition Language (DDL)?

a)SELECT
b)INSERT
c)UPDATE
d)CREATE

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Question 28General Knowledge

Which connect the two Sea in Suez Canal?

a)Arabian Sea and Mediterranean Sea
b)Mediterranean Sea and Red Sea
c)Persian Gulf and Black Sea
d)Black Sea and Arabian Sea

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Question 29General Knowledge

Who is first ICC ODI men's world Cup winner captain?

a)Clive Lloyd
b)Kapil Dev
c)Alan Border
d)Steve Waugh

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Question 30General Knowledge

Who won Nobel Peace prize in 2024?

a)David Baker
b)John Jumper
c)Nihon Hidankyo
d)Gary Ruvkun

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Question 31General Knowledge

The highest peak in Bangladesh is-

a)Saka Haphong
b)Bijoy Tajingdong
c)Dumlong
d)Keokradong

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Question 32General Knowledge

Strasbourg belongs to which country?

a)France
b)Germany
c)Canada
d)Russia

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Question 33Mathematics

A pipe can fill a tank in 4 hours, and another pipe can fill it in 6 hours. How much time will they take to fill the tank together?

a)40 hours
b)4.5 hours
c)2.4 hours
d)5 hours

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Question 34Mathematics

A went 5 meters to the north, then 3 meters to the east, and then 2 meters to the south. What is the distance from A's starting point to his final position?

a)4.24 meters
b)5.24 meters
c)3.24 meters
d)4 meters

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Question 35Mathematics

Mr. X uses 30% of his salary for one expense, 20% for another, and 10% for another. His remaining amount is 12,000 Taka. What is his total salary?

a)25,000TK
b)30,000TK
c)35,000TK
d)3,000TK

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Question 36Mathematics

The father's age is 36 and the son's age is 16. How many years ago was the father's age three times the son's age?

a)6 years ago
b)36 years ago
c)12 years ago
d)4 years ago

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Question 37Mathematics

There are 8 balls, and one of them is heavier than the other 7, which are of the same weight. How many weighings are required to guarantee finding the heavier ball?

a)1
b)2
c)3
d)4

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Question 38Software Engineering

Integration testing is the process of testing the _____ between two software units or modules.

a)Performance
b)Functionality
c)Interface
d)Security

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Question 39Programming

Which of the following operators should be preferred to overload as a global function rather than a member method?

a)Postfix ++
b)Comparison Operator
c)Insertion Operator <<
d)Prefix ++

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Question 40Algorithms

What are the advantages of Linear Search over Binary Search?

a)The array is ordered.
b)Fewer comparisons
c)Less time and space complexity
d)Linear search can be used irrespective of whether the array is sorted or not

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Question 41Software Engineering

Integration testing is the process of testing the _____ between two software units or modules.

a)Performance
b)Functionality
c)Interface
d)Security

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Question 42Cyber Security

Digital signature uses which algorithm for encryption?

a)Symmetric Key Algorithm
b)Asymmetric Key Algorithm
c)Hashing Algorithm only
d)Stream Cipher

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Question 43Digital Logic

Which device is needed to convert AC to DC?

a)Transformer
b)Rectifier
c)Inverter
d)Amplifier

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Question 44Cloud & Emerging Tech

What is Docker Hub and Docker?

a)Docker is a container platform, and Docker Hub is a cloud repository for Docker images
b)Docker is a virtual machine software, and Docker Hub is a database
c)Docker is a programming language, and Docker Hub is a code editor
d)Docker is a firewall, and Docker Hub is a security tool

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Question 45Networking

An IP address is given 192.168.3.0, needs 254 usable hosts. What is the CIDR value and subnet mask?

a)255.255.255.0
b)255.255.255.128
c)255.255.255.192
d)255.255.254.0

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