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Encyclopedia Ethereum · Entry 106

Chain IDs: why the same address can exist on different networks

AI-assisted research · separate automated verificationCorrections

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Ethereum
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5 cited records
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About 3 minutes
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In this article

At a glance

Key facts

Key facts for Chain IDs: why the same address can exist on different networks
FactDetailSource
Replay scopeEIP-155 changes the signed legacy transaction payload to include a chain ID.[1]
AddressAddress bytes alone do not specify a network.[3][1]
Typed dataAn EIP-712 domain can include chainId, but applications must implement replay protections.[2]
01

One address string can refer to several chain states

The same key can correspond to the same address bytes on several compatible networks while balances, contracts and transaction histories differ. Choosing a network changes which ledger you query or submit to.

A token contract address must therefore be paired with the chain. A familiar symbol and address display are insufficient if the wallet is on a different network.

02

Bind authorization to the intended domain

Without appropriate domain separation, a signed transaction valid in one setting might be accepted elsewhere. EIP-155 addresses this for the transaction format it specifies.

The protection depends on the actual transaction signing rules and chain configuration. It is not a certification system that makes any network using a particular number safe.

03

Off-chain signatures need their own checks

Typed-data applications can bind a signature to a chain and verifying contract, alongside an application name or version. Nonces and deadlines address additional reuse questions.

Review these fields when signing. A chain-aware transaction format does not automatically secure a separate permit or order-signature implementation.

Direct answers

Questions people ask

Does switching networks in my wallet move the funds?

No. It changes the network context the wallet displays or interacts with. Moving assets between networks requires a separate transfer or bridge mechanism.

Inspect the evidence

The answer and key facts have stable claim links. These records retain the scope and qualification when reused.

A chain ID is a number used to distinguish transaction-signing domains on Ethereum-compatible networks. EIP-155 incorporated it into legacy transaction signing to limit cross-chain replay. It does not identify an asset by itself, prove a network is trustworthy or automatically protect every off-chain signature.

Scope: Ethereum · data through 2026-10-02. Verification: verified · 2026-10-02T18:12:41.505Z.

Link to this claim
Replay scope: EIP-155 changes the signed legacy transaction payload to include a chain ID.

Scope: Ethereum · data through 2026-10-02. Verification: verified · 2026-10-02T18:12:41.505Z.

Link to this claim
Address: Address bytes alone do not specify a network.

Scope: Ethereum · data through 2026-10-02. Verification: verified · 2026-10-02T18:12:41.505Z.

Link to this claim
Typed data: An EIP-712 domain can include chainId, but applications must implement replay protections.

Scope: Ethereum · data through 2026-10-02. Verification: verified · 2026-10-02T18:12:41.505Z.

Link to this claim
Revision history
  1. — First publication after primary-source research and independent automated verification.

Source register

Sources and references

Retrieval dates and locators are recorded individually.
  1. Simple replay attack protectionEthereum Improvement Proposals

    Transaction chain ID domain separation; not blanket protection for all signatures.

    Locator: Specification · Version / scope: EIP/ERC-155; retrieved document hash recorded · Retrieved: 2026-10-02T17:03:42.312ZOpen source
  2. Typed structured data hashing and signingEthereum Improvement Proposals

    Typed-data encoding and domain fields; replay protection is application-specific.

    Locator: Specification; Security Considerations · Version / scope: EIP/ERC-712; retrieved document hash recorded · Retrieved: 2026-10-02T17:03:42.239ZOpen source
  3. Ethereum accountsethereum.org contributors

    Key-controlled and code-controlled accounts, balances, nonces and storage.

    Locator: Account types; An account examined; Account creation · Retrieved: 2026-10-02T17:03:41.958ZOpen source
  4. Permit Extension for EIP-20 Signed ApprovalsEthereum Improvement Proposals

    Signed token allowances, deadlines, nonces and domain checks.

    Locator: Specification; Security Considerations · Version / scope: EIP/ERC-2612; retrieved document hash recorded · Retrieved: 2026-10-02T17:03:42.295ZOpen source
  5. Ethereum JSON-RPCethereum.org contributors

    RPC response fields, transaction receipts, call simulation and log filtering.

    Locator: eth_getTransactionByHash; eth_getTransactionReceipt; eth_call; eth_getLogs; eth_getCode; eth_estimateGas; eth_getBalance; eth_getStorageAt; eth_getTransactionCount; default block parameter · Retrieved: 2026-10-02T17:03:42.060ZOpen source
How this article was made

Research and drafting use AI assistance. A separate automated review checks claims against primary sources; no external expert or named human review is implied. Publication, substantive editing, source retrieval and verification are recorded separately. This version was independently checked by an automated reviewer on 2 October 2026.

Editorial method and corrections

Degrees of Satoshi editorial project. “Chain IDs: why the same address can exist on different networks.” Published 2026-10-02; updated 2026-10-02. https://degreesofsatoshi.com/encyclopedia/ethereum-chain-id/