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Ethereum Flashcards

7 cards from real CBCP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. What is the 'Spurious Dragon' hard fork best known for introducing?

    Answer: EIP-161 state-clearing which removed empty accounts, and EIP-170 which capped contract code size at 24KB

    Spurious Dragon (Nov 2016) followed the Shanghai DoS attacks and cleaned up empty accounts while capping bytecode size.

  2. Which cryptographic curve does Ethereum use for signing transactions?

    Answer: secp256k1

    Ethereum uses the secp256k1 elliptic curve for ECDSA signatures, the same curve used by Bitcoin.

  3. What is a 'proxy pattern' in Ethereum smart contract upgradability?

    Answer: A contract that delegates calls to an implementation contract, allowing logic to be upgraded without changing the proxy's address

    The proxy holds state and forwards calls via DELEGATECALL to an upgradeable logic contract, preserving the original address.

  4. In Ethereum's ERC-721 standard, what does the tokenURI function return?

    Answer: A URI pointing to a JSON file describing the NFT's metadata including name, image, and attributes

    tokenURI returns a URL (often IPFS or HTTPS) to a JSON metadata file following the ERC-721 metadata standard.

  5. What problem does EIP-712 (Typed Structured Data Hashing and Signing) solve?

    Answer: Prevents signature replay across different contracts and chains by encoding domain-specific context into signed messages

    EIP-712 binds a signature to a specific contract, chain, and structured payload, making phishing and replay attacks harder.

  6. What is the 'SELFDESTRUCT' opcode's effect post-EIP-6780 (Cancun upgrade)?

    Answer: It only destroys the contract and sends ETH if called in the same transaction that created the contract; otherwise it only sends ETH

    EIP-6780 restricts SELFDESTRUCT so it only eliminates code/storage if creation and destruction occur in one transaction.

  7. In Ethereum's Casper FFG finality mechanism, what is required for a checkpoint to be 'justified'?

    Answer: A supermajority (≥2/3) of the total staked ETH must attest to a link between two checkpoints

    Casper FFG requires a two-thirds supermajority vote by stake weight to justify a source-to-target checkpoint link.