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Unit 3 - Practice Quiz

CSE306

1 Which of the following is the primary responsibility of the Data Link Layer?

A. End-to-end delivery of packets
B. Node-to-node delivery of frames
C. Routing of packets
D. Process-to-process delivery

2 In the context of framing, what is the purpose of Bit Stuffing?

A. To increase the data transfer rate
B. To detect errors in the frame
C. To distinguish frame delimiters from data by adding extra bits
D. To pad the frame to a minimum length

3 Which sublayer of the Data Link Layer is responsible for controlling access to the shared transmission medium?

A. Logical Link Control (LLC)
B. Media Access Control (MAC)
C. Network Control Protocol (NCP)
D. Physical Layer Control (PLC)

4 In a Stop-and-Wait ARQ system, if is the propagation delay and is the transmission time, what is the link utilization efficiency?

A. where
B. where
C. where
D.

5 What is the Hamming distance between the codewords 10101 and 11110?

A. 2
B. 3
C. 4
D. 5

6 To correct errors in a data stream, the minimum Hamming distance required in the coding scheme is:

A.
B.
C.
D.

7 In Cyclic Redundancy Check (CRC), if the generator polynomial is , what is the divisor in binary form?

A. 1011
B. 1101
C. 1001
D. 1110

8 When using a checksum for error detection, the sender calculates the sum of data segments using:

A. 1's complement arithmetic
B. 2's complement arithmetic
C. Modulo-2 arithmetic
D. Floating point arithmetic

9 Which of the following best describes Piggybacking?

A. Sending multiple frames at once
B. Attaching an acknowledgment to a data frame going in the reverse direction
C. Retransmitting a frame immediately after a timeout
D. Using a token to control access

10 In the Go-Back-N ARQ protocol, if bits are used for the sequence number, the sender window size must satisfy:

A.
B.
C.
D.

11 In Selective Repeat ARQ, if the sequence number space is size , what is the maximum size of the sender window?

A.
B.
C.
D.

12 What is the standard length of a MAC address?

A. 32 bits
B. 48 bits
C. 64 bits
D. 128 bits

13 A Layer 2 Switch makes forwarding decisions based on:

A. Source IP address
B. Destination IP address
C. Destination MAC address
D. Source MAC address

14 Which of the following is the Broadcast MAC address?

A. 00:00:00:00:00:00
B. FF:FF:FF:FF:FF:FF
C. 127.0.0.1
D. AA:BB:CC:DD:EE:FF

15 In Pure ALOHA, the vulnerable time (the time interval during which a collision can occur) is:

A. (Frame transmission time)
B.
C.
D. Indeterminate

16 What is the maximum theoretical efficiency (throughput) of Pure ALOHA?

A. 18.4%
B. 36.8%
C. 50%
D. 100%

17 What is the maximum theoretical efficiency of Slotted ALOHA?

A. 18.4%
B. 36.8%
C. 50%
D. 80%

18 In CSMA/CD, what does the station do immediately after detecting a collision?

A. It stops transmitting and waits for a random time
B. It continues transmitting to ensure all nodes detect the collision (Jamming Signal)
C. It switches to Slotted ALOHA mode
D. It drops the packet permanently

19 Which CSMA persistence method transmits immediately if the channel is idle, but transmits with probability ?

A. Non-persistent
B. 1-persistent
C. p-persistent
D. 0-persistent

20 The Binary Exponential Backoff algorithm is used in Ethernet to:

A. Calculate the CRC
B. Determine the window size for flow control
C. Determine the waiting time after a collision
D. Assign IP addresses

21 For CSMA/CD to work correctly, the minimum frame size must be:

A.
B.
C.
D. Equal to the header size

22 Why is CSMA/CD not typically used in Wireless LANs (802.11)?

A. Wireless signals travel faster
B. The Hidden Station problem makes collision detection difficult
C. Wireless has no bandwidth limit
D. CSMA/CD is too fast for wireless

23 Which protocol is used in Wireless LANs instead of CSMA/CD?

A. CSMA/CA (Collision Avoidance)
B. Pure ALOHA
C. Token Ring
D. Slotted ALOHA

24 Which of the following is a Controlled Access protocol?

A. ALOHA
B. CSMA/CD
C. Token Passing
D. Ethernet

25 In the Token Ring topology, what happens when a station holds the token?

A. It must forward the token immediately
B. It can transmit data frames
C. It enters sleep mode
D. It listens for collisions

26 The IEEE standard for Ethernet is:

A. 802.11
B. 802.3
C. 802.5
D. 802.15

27 What line coding scheme is used in Standard Ethernet (10BaseT)?

A. NRZ-L
B. Manchester Encoding
C. Differential Manchester
D. AMI

28 An Ethernet frame begins with a Preamble. What is its pattern?

A. Alternating 1s and 0s
B. All 1s
C. All 0s
D. Sequence of flag bytes

29 Which field in the Ethernet frame follows the Preamble and signals the beginning of the frame?

A. Source MAC
B. Length
C. SFD (Start Frame Delimiter)
D. CRC

30 What is the minimum frame length of a standard Ethernet frame?

A. 32 bytes
B. 46 bytes
C. 64 bytes
D. 128 bytes

31 If the data payload in an Ethernet frame is less than 46 bytes, what happens?

A. The frame is discarded
B. Padding is added to make it 46 bytes
C. The frame is sent as a 'runt' frame
D. The CRC is omitted

32 The CRC in an Ethernet frame is located in the:

A. Header
B. Preamble
C. Frame Check Sequence (FCS) field at the end
D. Type field

33 In 100Base-TX Ethernet, the '100' stands for:

A. 100 meters maximum length
B. 100 Mbps transmission speed
C. 100 nodes maximum
D. 100 MHz frequency

34 Which component splits a collision domain into multiple smaller collision domains?

A. Repeater
B. Hub
C. Switch
D. Cable

35 What is p-persistent CSMA?

A. Station transmits with probability 1 if idle
B. Station transmits immediately if idle
C. Station transmits with probability if idle, waits with probability
D. Station never transmits

36 Which Hamming code parity configuration (Even/Odd) ensures that the total number of 1s in the code is even?

A. Odd Parity
B. Even Parity
C. CRC Parity
D. Zero Parity

37 Calculate the Hamming code redundancy bits () required for a 7-bit data word (). (Using )

A. 3
B. 4
C. 2
D. 5

38 What is a Burst Error?

A. A single bit flip
B. Two or more bits in the data unit have changed
C. Error in the header only
D. Error caused by router congestion

39 The divisor in a CRC generator is always:

A. The same size as the data
B. One bit less than the generator polynomial degree
C. One bit more than the degree of the generator polynomial
D. Always 16 bits

40 In a switch, the Address Learning process involves:

A. Reading the destination MAC and storing it in the table
B. Reading the source MAC of incoming frames and mapping it to the port
C. Sending a broadcast to ask for names
D. Manually typing IP addresses

41 Which mechanism is used for Flow Control in the Data Link Layer?

A. CRC
B. Hamming Code
C. Sliding Window Protocol
D. Manchester Encoding

42 What is the result of in Modulo-2 arithmetic?

A. 0100
B. 0101
C. 0011
D. 1111

43 In Polling (Controlled Access), who controls the link access?

A. Any station
B. The Primary Station
C. The station with the token
D. The station with the highest IP

44 Gigabit Ethernet (1000Base-T) supports a data rate of:

A. 10 Mbps
B. 100 Mbps
C. 1000 Mbps
D. 10 Gbps

45 What is the purpose of the Inter-Frame Gap in Ethernet?

A. To detect collisions
B. To allow the receiver to process the previous frame and prepare for the next
C. To increase the data rate
D. To stuff bits

46 Which of the following is NOT a Random Access Protocol?

A. CSMA/CD
B. ALOHA
C. CSMA/CA
D. Reservation

47 In Byte Stuffing, if the flag byte appears in the data, what is inserted before it?

A. A zero bit
B. Another flag byte
C. An Escape (ESC) byte
D. A parity bit

48 The Maximum Transmission Unit (MTU) for standard Ethernet is typically:

A. 64 bytes
B. 1500 bytes
C. 1518 bytes
D. 4096 bytes

49 In 2D Parity check, errors can be detected:

A. Only in rows
B. Only in columns
C. In both rows and columns
D. Only if there is a single bit error

50 What happens if a switch receives a frame with a destination MAC address that is not in its forwarding table?

A. It drops the frame
B. It sends it back to the sender
C. It floods the frame out of all ports except the receiving one
D. It sends an ARP request