Unit 5 - Practice Quiz

1 Which elementary data link protocol assumes that the receiver can process incoming data at an infinite rate?

2 In the Stop-and-Wait protocol, what must the sender do after transmitting a data frame?

3 What is the primary difference between error detection and error correction?

4 Which of the following describes a 'burst error' in data communication?

5 What does CRC stand for in computer networks?

6 If a system uses 'even parity', what happens if the data bits have an odd number of 1s?

7 The Hamming code is primarily known for its ability to perform which function?

8 Which error detection method involves dividing the data into segments, adding them together using 1's complement arithmetic, and sending the complement of the sum?

9 What does MAC stand for in the context of the Data Link Layer?

10 The Data Link Layer is generally divided into two sublayers. One is the MAC sublayer; what is the other?

11 What is the basic rule for a station transmitting data in Pure ALOHA?

12 How does Slotted ALOHA improve upon Pure ALOHA?

13 What does the 'CD' in CSMA/CD stand for?

14 What does a station do first in the CSMA protocol?

15 Which of the following is a key characteristic of random access protocols?

16 What is the consequence of two stations transmitting at the same time in a random access network?

17 Which of the following is an example of a controlled access protocol?

18 In the polling access method, what is the role of the primary station?

19 What is the IEEE standard number for traditional Ethernet?

20 How long is a standard Ethernet MAC address?

21 If a data word has bits, what is the minimum number of redundant bits required for a Hamming code to correct single-bit errors?

22 To guarantee the correction of up to errors in a data frame, the minimum Hamming distance of the block code must be at least:

23 If a Cyclic Redundancy Check (CRC) uses a generator polynomial , how many bits will the CRC remainder appended to the data be?

24 In CRC, if the received message polynomial is perfectly divisible by the generator polynomial using modulo-2 arithmetic, what can be concluded?

25 Which of the following statements is true regarding a Two-Dimensional Parity Check?

26 A sender calculates the checksum for data words $1010$ and $0101$ using 4-bit one's complement arithmetic. What is the value of the checksum transmitted?

27 In a Stop-and-Wait protocol, if the propagation delay is and the transmission time is , the maximum link utilization (efficiency) is given by which formula? (Assume )

28 In a Go-Back-N ARQ protocol using bits for sequence numbers, what is the maximum permissible sender window size?

29 For a Selective Repeat ARQ protocol using 4 bits for sequence numbering, what is the optimal window size for both the sender and receiver?

30 Which of the following best describes the primary responsibility of the Medium Access Control (MAC) sublayer?

31 What is the maximum throughput (efficiency) of Pure ALOHA and Slotted ALOHA, respectively?

32 In Pure ALOHA, if the frame transmission time is , what is the vulnerable time during which a collision can occur?

33 In a CSMA/CD network, a station must transmit a frame of at least a minimum length () to ensure it can detect a collision before it finishes transmitting. If the network bandwidth is bps and the one-way propagation delay is , what is the formula for ?

34 Why is CSMA/CD generally not utilized in wireless networks (like Wi-Fi)?

35 In the standard Ethernet Binary Exponential Backoff algorithm, after collisions (where ), a station chooses a random delay time multiplied by the slot time. The random number is chosen from the range:

36 Which of the following controlled access methods requires one specific node to act as a primary node that authorizes secondary nodes to transmit data?

37 In a Token Passing network, what happens if the station holding the token currently has no data to send?

38 An Ethernet MAC address is a unique identifier assigned to a network interface controller. What is the length of an Ethernet MAC address?

39 In an IEEE 802.3 Ethernet frame, what is the purpose of the 7-byte Preamble followed by the 1-byte Start Frame Delimiter (SFD)?

40 What is the minimum and maximum size of an Ethernet frame payload (data field) in standard IEEE 802.3?

41 In a sliding window protocol, if the sequence numbers are represented using bits, what is the maximum permissible sender window size for Go-Back-N and Selective Repeat protocols, respectively, to ensure correct operation under worst-case delay?

42 If a code has a minimum Hamming distance of , what is the maximum number of errors it can detect () and the maximum number of errors it can correct ()?

43 To transmit data bits along with redundant bits using a Hamming code such that all single-bit errors are correctable, which of the following inequalities must strictly hold?

44 Given the generator polynomial and the message polynomial , what is the transmitted codeword polynomial in systematic form?

45 Consider a Two-Dimensional Parity Check scheme applied to an matrix of data bits. Which of the following error patterns is GUARANTEED to go undetected?

46 If the 16-bit Internet checksum is used, and a bit sequence of 16 zeros is altered to 16 ones during transmission while another 16-bit block changes from 16 ones to 16 zeros, what is the effect on the receiver's checksum validation?

47 Which of the following best describes the fundamental trade-off addressed by the Medium Access Control (MAC) sublayer in a broadcast network?

48 In Pure ALOHA, if the frame transmission time is , what is the vulnerable time, and at what offered load (in frames per ) is the maximum throughput achieved?

49 In a CSMA/CD network operating at 1 Gbps with a maximum cable length of 200 meters and signal propagation speed of m/s, what is the minimum frame size required to ensure collision detection?

50 In the Binary Exponential Backoff algorithm used after collisions in Ethernet, the sender chooses a random wait time from the interval . If , what is the probability that two colliding stations choose the same backoff time?

51 In a token ring network with stations, assuming the token propagation time around the ring is and frame transmission time is , what is the maximum channel utilization if the protocol uses Single-Token operation (release after reception)?

52 Which of the following fields in the classic IEEE 802.3 Ethernet frame is responsible for clock synchronization, and what is its specific bit pattern?

53 A CRC generator polynomial is defined as , where is a primitive polynomial of degree . Which set of errors is this guaranteed to detect?

54 In the Stop-and-Wait ARQ protocol, what is the link utilization given a frame transmission time , propagation delay , and assuming acknowledgment transmission time is negligible?

55 Why is CSMA/CD fundamentally unsuitable for wireless LANs (like 802.11), necessitating the use of CSMA/CA instead?

56 If an Ethernet frame is padded to reach the minimum frame size of 64 bytes, how does the receiving network layer know the actual length of the payload?

57 When constructing a Hamming code, parity bits are placed at bit positions that are powers of 2. For an 8-bit data sequence, at which positions (starting from 1) will the parity bits be placed, and what is the total codeword length?

58 In a slotted ALOHA system with active nodes where each transmits with probability in a slot, the efficiency is maximized at . As , what does the maximum efficiency asymptotically approach?

59 In a Reservation protocol where time is divided into a reservation frame containing minislots followed by data frames, if the system is heavily loaded such that every minislot results in a reservation, what is the maximum efficiency? (Let minislot length be and data frame length be )

60 In a communication channel with a high error rate, why does the Selective Repeat protocol generally outperform Go-Back-N, despite having higher memory requirements?