What Is a Chain ID? How Blockchain Networks Prevent Replay…
By Tobi Opeyemi Amure
AI summary of the source article
A chain ID is a numerical identifier that distinguishes blockchain networks and binds transaction signatures to a specific network. Ethereum introduced chain ID-based replay protection in 2016 through EIP-155 to prevent transactions from being reused across different chains.
Why it matters
Chain IDs reduce replay risks because without this protection, "a transaction valid on two networks with compatible transaction rules could potentially be replayed on both, creating unintended transfers or other actions."
Key facts
- Ethereum introduced chain ID-based replay protection in 2016 through EIP-155.
- Chain IDs help wallets and applications determine the active network, such as Ethereum Mainnet using chain ID 1 and Ethereum Classic using chain ID 61.
- Applications and wallets can retrieve the active chain ID using the eth_chainId JSON-RPC method.
Source excerpt · FinanceFeeds
A chain ID is a numerical identifier that distinguishes one blockchain network from another. It helps wallets, applications and blockchain clients identify the network for which a transaction is intended, particularly when signing transactions on Ethereum-compatible networks. For example, Ethereum Mainnet uses chain ID 1, while Ethereum Classic uses chain ID 61. Although both networks share some t…