FREE NFT Development On-Chain Royalties (EIP-2981) Questions and Answers

Question 1

A developer is implementing EIP-2981 for an NFT collection.
A marketplace needs to determine the royalty payment for a token with `tokenId` 789 that just sold for 10 ETH.
Which function signature must the marketplace call on the NFT contract to get this information?

Accepted Answer

royaltyInfo(uint256 _tokenId, uint256 _salePrice) external view returns (address receiver, uint256 royaltyAmount)

Answer

getRoyalty(uint256 _tokenId) external view returns (address receiver, uint256 percentage)

Answer

calculateRoyalty(uint256 _tokenId, uint256 _salePrice, address _currency) external view returns (uint256 royaltyAmount)

Answer

onSale(uint256 _tokenId, uint256 _salePrice) external payable

Question 2

What is the primary limitation of the EIP-2981 on-chain royalty standard?

Accepted Answer

It can only signal royalty information for a single recipient address.

Answer

It only supports royalty payments in Ether (ETH).

Answer

It is incompatible with the ERC-1155 multi-token standard.

Answer

It requires an excessively high amount of gas to calculate royalties.

Question 3

An NFT project implements EIP-2981, setting a 5% royalty. An owner sells one of the project's NFTs on a marketplace that has publicly stated it does not honor EIP-2981. What is the expected outcome for the creator regarding their royalty payment?

Accepted Answer

The creator will not receive a royalty payment because EIP-2981 is a signaling standard and relies on voluntary adoption by marketplaces.

Answer

The transaction will fail because the marketplace contract does not support the required royalty interface.

Answer

The creator will automatically receive 5% of the sale price, as the logic is enforced by the token's smart contract.

Answer

The marketplace is required to pay the royalty, but the creator must submit an off-chain claim to receive it.

Question 4

When a marketplace calls the `royaltyInfo(tokenId, salePrice)` function, what is the expected format of the `royaltyAmount` that is returned?

Accepted Answer

An absolute monetary value in the same denomination as the `salePrice`.

Answer

A percentage value, represented as a whole number (e.g., 5 for 5%).

Answer

A basis points value (e.g., 500 for 5%).

Answer

A struct containing the amount and the currency type (e.g., ETH, USDC).

Question 5

Which of the following describes a key design goal of the EIP-2981 standard?

Accepted Answer

To provide a minimal, gas-efficient, and standardized way for contracts to signal royalty information.

Answer

To create a complex on-chain system for enforcing royalty payments across all transfers.

Answer

To replace the `transferFrom` function with a new version that automatically splits funds.

Answer

To establish a centralized registry where all NFT royalty information must be stored.

Question 6

A developer wants to set different royalty percentages for different tokens within the same ERC-721 collection (e.g., rare tokens have a higher royalty). How can this be achieved while complying with EIP-2981?

Accepted Answer

By implementing logic within the `royaltyInfo` function that checks the `_tokenId` and calculates the `royaltyAmount` accordingly.

Answer

This is not possible, as EIP-2981 only allows for a single, contract-wide royalty percentage.

Answer

By deploying a separate EIP-2981 extension contract for each royalty tier.

Answer

By using the `setApprovalForAll` function to specify royalty information for each token.