Blockchain Technology Smart Contracts and dApps 3

Question 1

What is a 'proxy contract' pattern used for in Ethereum smart contract development?

Accepted Answer

Enabling upgradeable smart contracts

Answer

Proxy contracts delegate calls to an implementation contract, allowing the logic to be upgraded by pointing to a new implementation while preserving storage and address.

Question 2

In the context of dApps, what is a 'wallet connect' flow primarily used for?

Accepted Answer

Allowing users to sign transactions without exposing keys to the dApp

Answer

WalletConnect establishes a secure channel between a dApp and a mobile or hardware wallet so users can approve transactions without sharing private keys.

Question 3

What does 'gas limit' represent in an Ethereum transaction?

Accepted Answer

The maximum amount of computational work the sender authorizes

Answer

The gas limit is the maximum units of computation the sender permits for the transaction; unused gas is refunded and exhausted gas causes a revert.

Question 4

Which consensus mechanism does Ethereum use after 'The Merge' in 2022?

Accepted Answer

Proof of Stake

Answer

After The Merge, Ethereum switched from Proof of Work to Proof of Stake, where validators stake 32 ETH to propose and attest blocks.

Question 5

What is the role of an 'event' in a Solidity smart contract?

Accepted Answer

To log data cheaply that off-chain clients can subscribe to

Answer

Events write data to transaction logs, which are cheaper than storage and can be monitored by off-chain applications via Web3 subscriptions.

Blockchain Practice Test

Blockchain Practice Test

Blockchain Technology Smart Contracts and dApps 3