NPTEL Assignment Answers 2024 Blockchain and its Applications | Week 11

These are NPTEL Programming In Java Week 11 Assignment 11 Answers

Q1. If an attacker initially populates the victim node’s peer tables with attacker’s IP addresses in blockchain network, this attack is known as:

a. Sybil Attack

b. Eclipse Attack

с. Selfish Mining Attack

d. 51% Attack

Answer:

Q2. Which of the following can be used to identify a good blockchain use-case? (Mark multiple options if applied)

a. Participants

b. Assets

с. Transactions

d. Independent of everything

Answer:

These are Blockchain and its Applications Assignment 11 Answers

Q3. Alice is performing an Eclipse Attack, and If her IP replaces another attacker IP, the evicted IP is resent and eventually replaced by honest IP. Is this a valid statement?

a. Yes

b. No

Answer:

Q4. In a decentralized blockchain network, which scenario poses a significant risk known as the “51% Vulnerability”?

a. When a majority of users hold more than 51% of the cryptocurrency tokens.

b. When a single entity or a group controls more than 51% of the network’s computing power.

с. When more than 51% of the nodes in the network experience a temporary outage.

d. When more than 51% of the transactions in a block are invalid due to cryptographic errors.

Answer:

These are Blockchain and its Applications Assignment 11 Answers

Q5. Alice possesses 5 Bitcoins and initiates two separate transactions with the same Bitcoin. In which case does the double spending vulnerability occur?

a. Alice pays for a coffee and a book with the same 5 Bitcoins.

b. Alice accidentally sends 6 Bitcoins to a friend.

c. Alice sends 2 Bitcoins to one friend and 3 Bitcoins to another.

d. Alice checks her wallet balance but forgets to confirm the transaction.

Answer:

Q6. In a selfish mining attack, discovering more blocks by pool develops a longer lead on the public chain, and continues to keep these new blocks _________________.

a. Private

b. Public

Answer:

These are Blockchain and its Applications Assignment 11 Answers

Q7. Which of the following scenarios is NOT a good use case for blockchain technology?

a. A supply chain network where participants require real-time visibility into the movement and origin of goods.

b. An online voting system aiming to enhance transparency, reduce fraud, and ensure the integrity of election results.

c. A centralized banking system seeking to improve transaction speed and reduce costs.

d. A healthcare system aiming to securely share patient records among different healthcare providers for better coordinated care.

Answer:

Q8. What is a major problem with Proof Of Work?

a. It is difficult to implement

b. It is unreliable

c. Multiple miners have to be rewarded

d. It is CPU-intensive and consumes enormous amount of power.

Answer:

These are Blockchain and its Applications Assignment 11 Answers

Q9. In Practical Byzantine Fault Tolerance, __________.

a. A master node selects the next node that adds the next block

b. The node with most coins is chosen for adding the next block

c. The nodes elect a leader and that leader adds the next block

d. None of the above

Answer:

Q10. Alice places a bulk order for a cryptocurrency, and before it is processed, Bob, who is a miner, inserts his own buy order with a slightly higher price. In which case does the front-running attack occur?

a. Alice’s order is confirmed first due to network congestion.

b. Bob’s order is prioritized and confirmed ahead of Alice’s order.

c. Both Alice and Bob’s orders are cancelled due to conflicting transactions.

d. The network rejects both Alice and Bob’s orders, causing delays in confirmation.

Answer:

Q1. b. Eclipse Attack

Q2. a. Participants, b. Assets, c. Transactions

Q3. b. No

Q4. b. When a single entity or a group controls more than 51% of the network’s computing power.

Q5. a. Alice pays for a coffee and a book with the same 5 Bitcoins.

Q6. a. Private

Q7. c. A centralized banking system seeking to improve transaction speed and reduce costs.

Q8. d. It is CPU-intensive and consumes an enormous amount of power.

Q9. c. The nodes elect a leader and that leader adds the next block.

Q10. b. Bob’s order is prioritized and confirmed ahead of Alice’s order.