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Guide Flashcards

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

Read the first 7 Guide flashcards as text

  1. What is the main risk of a public mint function missing a reentrancy guard?

    Answer: A malicious receiver callback could mint extra tokens

    Without a guard, the onERC721Received callback could re-enter mint and exceed limits.

  2. Why might a developer choose ERC-721A over the standard OpenZeppelin ERC-721?

    Answer: It reduces gas for batch minting multiple tokens

    ERC-721A optimizes storage so minting several tokens in one transaction costs far less gas.

  3. What does 'on-chain' NFT metadata mean?

    Answer: Metadata and artwork encoded directly in the contract storage

    Fully on-chain NFTs store the SVG/JSON in the contract itself, removing external dependencies.

  4. Which Solidity visibility/access pattern protects an admin-only withdraw function?

    Answer: onlyOwner modifier

    An onlyOwner modifier restricts the withdraw function to the contract owner.

  5. What problem does setApprovalForAll being abused by a phishing site cause?

    Answer: An operator can transfer all your NFTs in the collection

    Granting setApprovalForAll to a malicious operator lets it move every token you own in that collection.

  6. When deploying an NFT contract, why verify the source on a block explorer?

    Answer: To let users read and trust the contract code

    Verification publishes the human-readable source, increasing transparency and collector confidence.

  7. What is the function typically used to permanently destroy an NFT?

    Answer: burn

    The burn function removes a token from circulation by sending it to an unrecoverable state.