# How does replica know which canister to serve from

**URL:** <https://forum.dfinity.org/t/how-does-replica-know-which-canister-to-serve-from/2438>\
**Category:** Developers\
**Created:** [April 9, 2021, 10:59pm UTC](https://forum.dfinity.org/t/how-does-replica-know-which-canister-to-serve-from/2438 "2021-04-09T22:59:03Z")\
**Posts on this page:** 1\
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**Author:** ![nomeata](https://sea1.discourse-cdn.com/flex023/user_avatar/forum.dfinity.org/nomeata/32/733_2.png) [@nomeata](https://forum.dfinity.org/u/nomeata)\
**Post date:** [April 20, 2021, 8:35am UTC](https://forum.dfinity.org/t/how-does-replica-know-which-canister-to-serve-from/2438/3 "2021-04-20T08:35:07Z")

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Sorry, late repsonse, but it’s not the referrer. Eventually it will be the `Host` (`canister-id.ic0.app`); for local development a query parameter `?canister_id=abcde-fgh` is used.

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