Ethereum's Transactions, Validation, and Upgrades BDC Practice Questions (Page 2)

Questions 6–10

1. 6application · medium

   A developer is building a wallet that sends multiple transactions from the same account in quick succession. The wallet currently uses a fixed nonce value for all transactions. Users report that only the first transaction is confirmed and the rest are stuck. What is the most likely cause and the correct fix?

   • AThe nonce is not incremented per transaction; the wallet must track and increment the nonce for each outgoing transaction.
   • BThe gas price is too low; increase the gas price for all pending transactions.
   • CThe signature is invalid because the private key is not stored securely; re-import the key.
   • DThe account balance is insufficient; the wallet should request more ETH from a faucet.
   Reveal Solution Discussion Select an answer first
2. 7application · medium

   A developer wants to propose a change to Ethereum that alters the gas cost of a specific opcode. What is the correct process to get this change implemented?

   • ASubmit an EIP, gather community consensus, and coordinate a network upgrade (hard fork) at a specific block number.
   • BCreate a soft fork that only affects new transactions, leaving old blocks unchanged.
   • CDeploy a new smart contract that overrides the opcode's gas cost for all transactions.
   • DAsk the Ethereum Foundation to update the client software directly without a formal proposal.
   Reveal Solution Discussion Select an answer first
4. 8foundation · easy

   Which component of an Ethereum transaction is NOT part of the signed data but is derived from the signature?

   • Avalue
   • Bfrom
   • CgasLimit
   • Dto
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5. 9expert · hard

   A developer is debugging a transaction that was rejected by the network. The transaction has a valid signature, the nonce is correct, and the account has sufficient balance. However, the transaction was rejected. What is the most likely cause?

   • AThe transaction's data field is empty, which is invalid for a contract call.
   • BThe transaction's chain ID is missing, but the network allows it.
   • CThe transaction's priority fee is set to zero, making it unattractive to validators.
   • DThe transaction's gas limit is lower than the intrinsic gas required for the transaction.
   Reveal Solution Discussion Select an answer first
6. 10expert · medium

   A developer is designing a smart contract that performs a complex computation. They are concerned about the transaction failing due to out-of-gas. Which strategy is most effective to avoid out-of-gas failures?

   • AOptimize the contract code to reduce gas consumption and set a gas limit that covers the estimated usage with a buffer.
   • BSplit the computation into multiple transactions, each with a lower gas limit.
   • CSet the gas limit to the maximum possible value to ensure the transaction never runs out of gas.
   • DUse a higher gas price to prioritize the transaction, which also increases the gas limit.
   Reveal Solution Discussion Select an answer first