Q#1: Data Link Control (DLC) is responsible for:
(A) Reliable delivery of data frames between two nodes
(B) Routing packets across the network
(C) Modulation of signals
(D) Multiplexing
Answer: (A) Reliable delivery of data frames between two nodes
Q#2: The main functions of DLC include:
(A) Framing, error control, flow control
(B) Routing only
(C) Encryption
(D) Multiplexing
Answer: (A) Framing, error control, flow control
Q#3: Framing is necessary to:
(A) Identify start and end of data frames
(B) Detect errors
(C) Amplify signals
(D) Modulate data
Answer: (A) Identify start and end of data frames
Q#4: Error control in DLC ensures:
(A) Correct reception of frames
(B) Bandwidth allocation
(C) Signal modulation
(D) Routing
Answer: (A) Correct reception of frames
Q#5: Flow control prevents:
(A) Sender overwhelming the receiver
(B) Noise in transmission
(C) Signal loss
(D) Delay
Answer: (A) Sender overwhelming the receiver
Q#6: Types of flow control include:
(A) Stop-and-wait
(B) Sliding window
(C) Both A and B
(D) None
Answer: (C) Both A and B
Q#7: Stop-and-wait flow control:
(A) Sender waits for acknowledgment before sending next frame
(B) Sender sends all frames at once
(C) Uses multiplexing
(D) None
Answer: (A) Sender waits for acknowledgment before sending next frame
Q#8: Sliding window protocol allows:
(A) Multiple frames to be sent before acknowledgment
(B) Single frame only
(C) Fixed frequency
(D) None
Answer: (A) Multiple frames to be sent before acknowledgment
Q#9: Window size in sliding window protocol:
(A) Number of frames sent without acknowledgment
(B) Number of bits per frame
(C) Bandwidth
(D) None
Answer: (A) Number of frames sent without acknowledgment
Q#10: Acknowledgment (ACK) indicates:
(A) Successful reception of frame
(B) Error in frame
(C) Start of transmission
(D) End of frame
Answer: (A) Successful reception of frame
Q#11: Negative acknowledgment (NAK) indicates:
(A) Error detected in frame
(B) Successful reception
(C) Start of frame
(D) End of transmission
Answer: (A) Error detected in frame
Q#12: Two types of error control:
(A) ARQ and FEC
(B) TDM and FDM
(C) Parity and checksum only
(D) None
Answer: (A) ARQ and FEC
Q#13: Stop-and-wait ARQ retransmits:
(A) Frame if acknowledgment not received
(B) All frames
(C) Only parity
(D) None
Answer: (A) Frame if acknowledgment not received
Q#14: Go-Back-N ARQ retransmits:
(A) All frames from the erroneous frame onward
(B) Only erroneous frame
(C) Single bit
(D) None
Answer: (A) All frames from the erroneous frame onward
Q#15: Selective Repeat ARQ retransmits:
(A) Only frames that were received in error
(B) All frames
(C) Single-bit frames
(D) None
Answer: (A) Only frames that were received in error
Q#16: Framing methods include:
(A) Character count, byte stuffing, bit stuffing
(B) Parity check
(C) CRC only
(D) None
Answer: (A) Character count, byte stuffing, bit stuffing
Q#17: Character count method:
(A) Specifies number of characters in frame
(B) Uses start and end flags
(C) Uses parity only
(D) None
Answer: (A) Specifies number of characters in frame
Q#18: Byte stuffing uses:
(A) Special characters (flags) to mark frame boundaries
(B) Bits for error detection
(C) Multiplexing
(D) None
Answer: (A) Special characters (flags) to mark frame boundaries
Q#19: Bit stuffing:
(A) Inserts 0 after consecutive 1s to avoid flag confusion
(B) Adds parity bits
(C) Uses bytes
(D) None
Answer: (A) Inserts 0 after consecutive 1s to avoid flag confusion
Q#20: Error detection methods at DLC layer:
(A) Parity, CRC, checksum
(B) Hamming code
(C) Reed-Solomon
(D) All of the above
Answer: (D) All of the above
Q#21: DLC layer ensures:
(A) Reliable node-to-node delivery
(B) End-to-end delivery
(C) Multiplexing
(D) None
Answer: (A) Reliable node-to-node delivery
Q#22: Acknowledgment schemes include:
(A) Positive ACK
(B) Negative ACK (NAK)
(C) Both A and B
(D) None
Answer: (C) Both A and B
Q#23: Stop-and-wait disadvantage:
(A) Low efficiency for long delay links
(B) Complex implementation
(C) Cannot detect errors
(D) None
Answer: (A) Low efficiency for long delay links
Q#24: Sliding window advantage:
(A) Higher throughput
(B) Low delay
(C) Simple
(D) None
Answer: (A) Higher throughput
Q#25: Go-Back-N uses:
(A) Single acknowledgment for cumulative frames
(B) Individual acknowledgment
(C) No acknowledgment
(D) None
Answer: (A) Single acknowledgment for cumulative frames
Q#26: Selective Repeat requires:
(A) Individual acknowledgment for each frame
(B) Cumulative acknowledgment
(C) No acknowledgment
(D) None
Answer: (A) Individual acknowledgment for each frame
Q#27: Flow control prevents:
(A) Buffer overflow at receiver
(B) Signal loss
(C) Noise
(D) Modulation errors
Answer: (A) Buffer overflow at receiver
Q#28: Bit-oriented protocols use:
(A) Flags and bit stuffing
(B) Character count
(C) Bytes only
(D) None
Answer: (A) Flags and bit stuffing
Q#29: Character-oriented protocols use:
(A) Byte values to identify frame boundaries
(B) Bit flags
(C) CRC only
(D) None
Answer: (A) Byte values to identify frame boundaries
Q#30: DLC frame structure includes:
(A) Header, data, trailer
(B) Header and payload only
(C) Data only
(D) None
Answer: (A) Header, data, trailer
Q#31: Header fields contain:
(A) Source and destination address
(B) Sequence number
(C) Control information
(D) All of the above
Answer: (D) All of the above
Q#32: Trailer usually contains:
(A) Error detection code (CRC or checksum)
(B) Header
(C) Control bits only
(D) None
Answer: (A) Error detection code (CRC or checksum)
Q#33: Acknowledgment number indicates:
(A) Next expected frame
(B) Last received frame
(C) Sequence number
(D) None
Answer: (A) Next expected frame
Q#34: Flow control and error control can be implemented:
(A) Separately or combined
(B) Only together
(C) Only separately
(D) None
Answer: (A) Separately or combined
Q#35: Bit stuffing prevents:
(A) Accidental flag pattern in data
(B) Noise
(C) Delay
(D) Bandwidth loss
Answer: (A) Accidental flag pattern in data
Q#36: Sliding window maximum size depends on:
(A) Sequence number bits
(B) Data bits
(C) Bandwidth
(D) None
Answer: (A) Sequence number bits
Q#37: ACK timeout in ARQ triggers:
(A) Retransmission
(B) Flow control
(C) Frame numbering
(D) None
Answer: (A) Retransmission
Q#38: Bit-oriented protocol example:
(A) HDLC
(B) ASCII
(C) EBCDIC
(D) None
Answer: (A) HDLC
Q#39: Stop-and-wait efficiency:
(A) = Transmission time / (Transmission + propagation + acknowledgment)
(B) = Transmission time only
(C) = Bandwidth / data size
(D) None
Answer: (A) = Transmission time / (Transmission + propagation + acknowledgment)
Q#40: Sliding window protocol prevents:
(A) Both flow and error problems
(B) Only flow
(C) Only errors
(D) None
Answer: (A) Both flow and error problems
Q#41: Sequence numbers are used to:
(A) Detect lost frames
(B) Detect errors
(C) Control flow
(D) All of the above
Answer: (D) All of the above
Q#42: Cyclic redundancy check (CRC) is:
(A) Polynomial-based error detection in DLC
(B) Parity bit only
(C) Stop-and-wait only
(D) None
Answer: (A) Polynomial-based error detection in DLC
Q#43: Frame retransmission occurs when:
(A) ACK not received or NAK received
(B) Timeout occurs
(C) Both A and B
(D) None
Answer: (C) Both A and B
Q#44: Bit-oriented protocols are suitable for:
(A) Both text and binary data
(B) Only text
(C) Only binary
(D) None
Answer: (A) Both text and binary data
Q#45: Header sequence number field allows:
(A) Proper frame ordering
(B) Error detection
(C) Flow control
(D) All of the above
Answer: (D) All of the above
Q#46: ARQ protocols are part of:
(A) DLC layer
(B) Network layer
(C) Physical layer
(D) None
Answer: (A) DLC layer
Q#47: Sliding window requires:
(A) Buffers at sender and receiver
(B) Only sender buffer
(C) Only receiver buffer
(D) None
Answer: (A) Buffers at sender and receiver
Q#48: Acknowledgment numbers wrap around:
(A) Sequence number modulo maximum value
(B) Random
(C) Never wrap
(D) None
Answer: (A) Sequence number modulo maximum value
Q#49: Flow control is necessary because:
(A) Receiver may process slower than sender
(B) Network congestion
(C) Both A and B
(D) None
Answer: (C) Both A and B
Q#50: Primary goal of Data Link Control:
(A) Reliable node-to-node communication
(B) End-to-end routing
(C) Multiplexing
(D) Modulation
Answer: (A) Reliable node-to-node communication