Blockchain Test 1

Question 1

Which of the following are real-world Blockchain applications?

Accepted Answer

All of the above

Answer

A video sharing website

Answer

Voting

Answer

Identity management

Question 2

On a public Blockchain, who can read the records?

Accepted Answer

Everyone on the Blockchain

Answer

No one

Answer

The users with access permissions

Answer

Only the creator

Question 3

A block header is made up of which item(s)?

Accepted Answer

The hash of the previous block

Answer

The time stamp of the block and the genesis block hash

Answer

The hash of every transaction in a specific block and the next block

Answer

The hash of the Merkle root and the header of the previous block

Question 4

What happens if two blocks are confirmed simultaneously?

Accepted Answer

Which block is added to the Blockchain is decided by the nodes.

Answer

Both chains are removed from the pool, and the unconfirmed transactions are re-added.

Answer

The Orderer Block verifies which block has the most transactions confirmed.

Answer

The blocks are broken up into two chains. Each chain is then extended by adding blocks until it reaches its maximum length. The Blockchain is therefore defined as the longest chain.

Question 5

For cryptocurrencies, which of the following challenges did Blockchain solve?

Accepted Answer

Anonymity

Answer

Double Spending

Answer

Destination of currencies

Answer

None of the above

Question 6

Which of the following attacks requires only a single account and only uses standard blockchain operations?

Accepted Answer

Replay Attack

Answer

51% Attack

Answer

Eclipse Attack

Answer

Routing Attack

Question 7

Which of the following methods for generating pseudo-random numbers for smart contracts is recommended?

Accepted Answer

External oracle

Answer

Block hashes

Answer

Private variables

Answer

Private functions

Question 8

Which of the following biockchains has an architectural design that is channel-focused?

Accepted Answer

Hyperledger

Answer

Ethereum

Answer

Corda

Answer

None of the above

Question 9

What is one typical way for "chaining" pieces of data together in sequence in a blockchain design?

Accepted Answer

Store the hash of the previous block within the current block

Answer

Writing each block into a separate file on the hard disk of the node

Answer

Assigning an order number to each block so they can be sorted when requested

Answer

Having the genesis node store an ordered, mutable array of block hashes