Data Transmission and Error Detection Quiz

Which of the following is a key feature of the ARQ protocol?

• Data encryption

• Packet acknowledgment

• Data compression

• Parallel processing

Answer explanation

The ARQ (Automatic Repeat reQuest) protocol primarily relies on packet acknowledgment to ensure reliable data transmission. It requires the receiver to acknowledge received packets, allowing the sender to retransmit lost packets.

What happens to the packets after a NACK is received in Go-Back-N ARQ?

• They are stored

• They are resent

• They are ignored

• They are encrypted

Answer explanation

In Go-Back-N ARQ, when a NACK (Negative Acknowledgment) is received, it indicates that a packet was not received correctly. Consequently, all subsequent packets are resent to ensure data integrity.

What is the main disadvantage of Stop-N-Wait ARQ?

• High complexity

• Slow data transmission

• High error rate

• Requires large bandwidth

Answer explanation

The main disadvantage of Stop-N-Wait ARQ is slow data transmission. This protocol waits for an acknowledgment after each packet, leading to idle time and reduced throughput, especially in high-latency networks.

What is the main function of buffering in Selective Repeat ARQ?

• To discard packets

• To resend packets

• To handle out-of-order frames

• To ignore packets

Answer explanation

The main function of buffering in Selective Repeat ARQ is to handle out-of-order frames. This allows the receiver to store frames that arrive out of sequence until the missing frames can be received and processed.

Which layer is directly above the Data Link Layer in the OSI model?

• Network Layer

• Physical Layer

• Transport Layer

• Application Layer

Answer explanation

The Network Layer is directly above the Data Link Layer in the OSI model. It is responsible for routing data packets between devices across different networks, making it the correct choice.

What is the purpose of using parity in ECC?

• To detect errors

• To increase data speed

• To compress data

• To encrypt data

Answer explanation

The purpose of using parity in ECC (Error Correction Code) is to detect errors in data transmission or storage. Parity bits help identify discrepancies, ensuring data integrity.

What is the parity bit for the last column in the ECC example?

• 1

• 0

• 2

• 3

Answer explanation

The parity bit for the last column is determined by counting the number of 1s. If the count is odd, the parity bit is 1; if even, it's 0. In this case, the count is odd, so the correct parity bit is 1.

What is the parity bit for the fourth row in the ECC example?

• 0

• 1

• 2

• 3

Answer explanation

The parity bit for the fourth row is calculated by ensuring the total number of 1s is even. In this case, the count results in an even number, so the parity bit is 0, making the correct answer 0.

In a 2D parity error detection system, what does the intersection of a row and column with parity bit errors indicate?

• The location of the bad bit

• The start of a new data block

• The end of the data stream

• The need for data compression

Answer explanation

In a 2D parity error detection system, if both a row and a column show parity bit errors, their intersection indicates the exact location of the bad bit, allowing for targeted correction.

How is a single bit error identified in a 2D parity system?

• By checking the data size

• By finding the intersection of row and column errors

• By compressing the data

• By encrypting the data

Answer explanation

In a 2D parity system, a single bit error is identified by checking the parity bits of the corresponding row and column. If both the row and column parity indicate an error, their intersection points to the exact location of the error.