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Chapter 5: Data Communication, Computer Network and Organization: MCQ Practice for the NEC License Exam (AItE)

This chapter contributes 10 of the 100 questions in the IT Engineering license exam. Below are its subtopics, what is usually tested, and 12 free sample questions with answers and explanations.

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Subtopics in this chapter

What is usually tested

Networking questions follow the layers: the OSI and TCP/IP models, devices, Ethernet and CSMA/CD, IP addressing and subnetting, routing protocols, IPv6, TCP versus UDP, ports, congestion control, DNS, e-mail and FTP. Security questions cover cryptography, RSA, digital signatures, firewalls and common attacks. The chapter also includes socket programming calls, WAN technologies such as frame relay and ATM, and computer organisation: control units, addressing modes, RISC versus CISC, pipelining, cache memory and multiprocessors.

Sample questions with answers

Try each question before opening the answer. These 12 are taken from the 210 questions for this chapter in the practice bank.

1. Which OSI layer is responsible for routing? (5.1 Introduction to computer networks, physical layer and data link layer)

  1. Data link
  2. Network
  3. Transport
  4. Session
Show answer
Answer: B. Network
The network layer handles logical addressing and routing.

2. Which protocol maps an IP address to a MAC address? (5.1 Introduction to computer networks, physical layer and data link layer)

  1. ARP
  2. DNS
  3. RARP
  4. DHCP
Show answer
Answer: A. ARP
ARP resolves IP addresses to MAC addresses.

3. TCP establishes a connection using: (5.2 Network layer and transport layer)

  1. Two-way handshake
  2. Three-way handshake
  3. Four-way handshake
  4. No handshake
Show answer
Answer: B. Three-way handshake
SYN, SYN-ACK, ACK: the three-way handshake.

4. The default subnet mask of a Class C network is: (5.2 Network layer and transport layer)

  1. 255.0.0.0
  2. 255.255.0.0
  3. 255.255.255.0
  4. 255.255.255.255
Show answer
Answer: C. 255.255.255.0
Class C default mask is /24 = 255.255.255.0.

5. The default port number for HTTPS is: (5.3 Application layer and network security)

  1. 80
  2. 21
  3. 443
  4. 8080
Show answer
Answer: C. 443
HTTPS uses port 443 by default.

6. The default port number of HTTP is: (5.3 Application layer and network security)

  1. 25
  2. 80
  3. 53
  4. 110
Show answer
Answer: B. 80
Port 25 is SMTP, 53 is DNS and 110 is POP3.

7. In a digital receiver, sampling time (clock) recovery means: (5.4 Synchronization, network management, protocols and programming model)

  1. Deriving the timing of the bit intervals from the received signal
  2. Finding the first bit of each frame
  3. Measuring the power of the received signal
  4. Converting the signal to a higher frequency
Show answer
Answer: A. Deriving the timing of the bit intervals from the received signal
The receiver must sample each bit at the correct instant, so it extracts the clock from the incoming data.

8. Frame time recovery (framing) at a receiver means: (5.4 Synchronization, network management, protocols and programming model)

  1. Recovering the frequency of the carrier
  2. Identifying where each frame begins in the received bit stream
  3. Amplifying the received frames
  4. Removing noise from the frames
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Answer: B. Identifying where each frame begins in the received bit stream
A known framing pattern is searched for so that the bits can be assigned to the right time slots.

9. In a microprogrammed control unit, the control signals are generated from: (5.5 Control and central processing units)

  1. The input devices
  2. A fixed network of gates and flip-flops
  3. The main memory of the user programs
  4. Microinstructions stored in a control memory
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Answer: D. Microinstructions stored in a control memory
A hardwired control unit, in contrast, generates the signals with logic circuits.

10. Compared with microprogrammed control, hardwired control is: (5.5 Control and central processing units)

  1. Faster but harder to modify
  2. Slower but easier to modify
  3. Slower and harder to modify
  4. Faster and easier to modify
Show answer
Answer: A. Faster but harder to modify
Changing a hardwired design means changing the circuits; a microprogram can simply be rewritten.

11. Cache memory is placed between: (5.6 Computer arithmetic and memory system and IO)

  1. Hard disk and RAM
  2. CPU and hard disk
  3. RAM and I/O devices
  4. CPU and main memory
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Answer: D. CPU and main memory
Cache sits between the CPU and main memory to reduce access time.

12. Booth's algorithm is used for: (5.6 Computer arithmetic and memory system and IO)

  1. Detecting errors in memory
  2. Dividing unsigned binary numbers
  3. Converting binary numbers to decimal
  4. Multiplying signed binary numbers in two's complement form
Show answer
Answer: D. Multiplying signed binary numbers in two's complement form
It handles positive and negative multipliers uniformly and skips over runs of identical bits.

Practise this chapter

The full mock tests mix 10 questions from this chapter with 10 from each of the other nine, under the real 2-hour limit. Chapter practice mode lets you work through this chapter alone, untimed, with the explanation shown after every question.

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