On-Chain Royalties (EIP-2981) Flashcards

Before EIP-2981, why were royalties inconsistent across marketplaces?

Answer: Each marketplace used its own proprietary, off-chain royalty configuration

Without a standard, every marketplace stored and applied royalties differently, so they didn't carry across platforms.

What is the primary benefit of storing royalty info on-chain via EIP-2981?

Answer: Any marketplace can read the same royalty data interoperably

On-chain, standardized royalty data lets all platforms query the same source, improving interoperability.

Which gas consideration favors a default royalty over per-token royalties?

Answer: A default avoids writing storage for every token

Using a single default avoids the storage write cost of recording a royalty for each individual token.

Can the royalty receiver address differ from the contract owner or NFT creator?

Answer: Yes, the receiver is set independently and can be any address

The royalty receiver is configured separately and can point to any address, such as a treasury or splitter.

What does it imply if a contract's supportsInterface returns false for 0x2a55205a?

Answer: The contract does not advertise EIP-2981 royalty support

A false return for the EIP-2981 interface ID means the contract does not declare royalty support under the standard.

When migrating a collection's royalties, what is a safe pattern for updating the default fee?

Answer: Restrict _setDefaultRoyalty to an owner/admin role

Gating the royalty setter behind an access-control role prevents unauthorized changes to fees or receivers.

How does EIP-2981 interact with secondary-sale royalties on resales?

Answer: It provides the same royaltyInfo lookup on every resale, so each compliant sale can pay the receiver

Marketplaces can call royaltyInfo on any sale, including resales, so each compliant secondary sale pays the receiver.