Quiz 2 - Introduction to Blockchain Technology
DeFi MOOC
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Question 1 - Blockchain consensus is building a public append-only data structure. Which of the following statements is incorrect regarding blockchain consensus properties? *
1 point
Question 2 - Which of the following statements is incorrect for a hash function H: M → T? *
1 point
Question 3 - Which of the following is not a blockchain scaling solution? *
1 point
For fun
Traders/bots on Ethereum use "fancy" addresses with leading/trailing 0s. (e.g., 0x00000a600e64c26be24f64169c89f21c1f530000). This can be easily accomplished with brute force. Try the python code we share below offline. Remember you should never share your private key with anyone!

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# install web3py first
# !pip install web3
from eth_account import Account
import secrets
acct = None

expect = "000"

while acct is None or acct.address[2:2+len(expect)] != expect:
priv = secrets.token_hex(32)
private_key = "0x" + priv
acct = Account.from_key(private_key)

print("DO NOT SHARE YOUR PRIVATE KEY WITH ANYONE:", private_key)
print("Address:", acct.address)
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Bonus questions
Question 1 - The difficulty of the proof of work in Ethereum is set to 13 seconds. What would go wrong if it were changed to 1 second, without modifying the other parameters?
1 point
Clear selection
Question 2 - Suppose two groups independently implement the Ethereum protocol. Some miners run implementation A and other miners run implementation B. At some point, an attacker finds a vulnerability in implementation A that causes miners running that implementation to accept invalid transactions. Suppose 90% of the mining power runs the buggy implementation and 10% runs the non-buggy one. What will happen to the blockchain once an invalid transaction with high gas price is propagated within the network?
1 point
Clear selection
Question 3 - (Continue to the second question), Suppose 10% of the mining power runs the buggy implementation and 90% runs the non-buggy one. What will happen to the blockchain once a block containing an invalid transaction is submitted to the network?
1 point
Clear selection
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