Question: QUESTION 1 What is the difference between Blockchain and Bitcoin? A.There is no difference and the terms can be used interchangeably. B.Bitcoin is the underlying
QUESTION 1
What is the difference between Blockchain and Bitcoin?
A.There is no difference and the terms can be used interchangeably.
B.Bitcoin is the underlying technology and blockchain is one famous application.
C.Blockchain is the underlying technology and Bitcoin is one famous application.
D.Blockchain and Bitcoin are too completely non-related concepts.
QUESTION 2
Which of the following statement characterizes a Hash function?
A.Digests cannot be reversed to produce inputs in theory.
B.A tiny change to the input slightly alters the digest.
C.Hash functions deterministically transform data of arbitrary size (inputs) to data of fixed size (digests)
D.Hash functions are two-way functions, so the input can be derived from the output, and vice-versa
QUESTION 3
Which of the following is true of SHA-256 hash function?
A.It has been proven not to have a collision
B.However secure it is Bitcoin adopts other hash functions
C.No collision has ever been publicly found
ID. t has been proven that there is no fast way to find collisions
QUESTION 4
Which of these keys are required for verifying a signature?
A.The secret key
B.The public key
C.Both the secret and the public key
D.None. Keys are required only for signing; anyone can verify the signature without a key
QUESTION 5
For any blockchain, what data is always recorded within each block?
A.The previous block's hash
B.The current block's hash
C.The next block's hash
D.All previous blocks' hashes
QUESTION 6
Who keeps record of the ledger for Bitcoin transactions?
A.Satoshi Nakamoto
B.A group of core developers
C.The central bank
D.miners
QUESTION 7
Which of the following statement is true about the bitcoin peer-to-peer network?
A. Each node is directly connected to all other nodes in the network
B. Each node is directly connected to a server who ensures the well-functioning of Bitcoin
C. Different nodes may hear about the same transaction at different times
D.All nodes agree on the status quo of all transactions at all times
QUESTION 8
Suppose miner Alice closely adheres to the "longest-chain rule". While building block 12 she receives a message about another block 12. What should Alice do?
A.Ignore the just-received block 12 and keep building her block 12.
B.Stop immediately and start building block 13 appending to the just-received block 12.
C.Verify the just-received block 12 is correct; if so immediately stop building her block 12 and start building block 13 appending to the just-received block 12.
D.Wait until block 13 appending the just-received block 12 (if she still not done with her block 12) is received to abandon her block 12 and keep building block 14 appending it.
QUESTION 9
Which mechanism most directly prevents a user from spending the same cryptocurrency more than once (double-spend attack) in a blockchain-based payment system?
A.Secrete-public key cryptography
B.Merkle tree data structure
C.A central bookkeeper or a large group of miners
D.Peer-to-peer network
QUESTION 10
Which of the following steps is not required from a central party (e.g. Scrooge) to maintain an immutable/trustworthy blockchain?
A.Publish the hash of the latest block
B.Publish the signature of the hash of the latest block
C.Publish its public key
D.Publish its secret key
QUESTION 11
Two conflicting transactions A -> B and A -> C are both broadcast almost simultaneously from different nodes, what determines which one will eventually end up in the blockchain?
A.The transaction that reaches the majority of nodes first will win
B.The transaction that was broadcast first will win
C.The miner who finds the next block will likely resolve the tie by including one of the transactions in the block
D.Each node has its own blockchain version containing the transaction it heard about first
QUESTION 12
Which of the following statement precisely explains why in bitcoin mining it is a Nash equilibrium for all miners to follow the "longest chain rule" (assuming that all miners have negligible computing powers compared to the global computing power)
A.When all other miners follow the longest chain rule, it is better to follow the longest chain rule too
B.When all other miners do not follow the longest chain rule, it is better to not follow the longest chain rule either
C.When all other miners follow the longest chain rule, it is better to not follow the longest chain rule
D.When all other miners do not follow the longest chain rule, it is better to follow the longest chain rule
QUESTION 13
Which of the following statement is correct for a game given by the following payoff matrix:
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