# SEO - Will using custom domains alongside the CANISTER\_ID.icp0.io cause duplicate content issues? **URL:** https://forum.dfinity.org/t/seo-will-using-custom-domains-alongside-the-canister-id-icp0-io-cause-duplicate-content-issues/28817 **Category:** Developers **Tags:** Frontend **Created:** [March 24, 2024, 9:08am UTC](https://forum.dfinity.org/t/seo-will-using-custom-domains-alongside-the-canister-id-icp0-io-cause-duplicate-content-issues/28817 "2024-03-24T09:08:14Z") **Posts on this page:** 2 **Page:** 1
### Author: ![karim](https://sea1.discourse-cdn.com/flex023/user_avatar/forum.dfinity.org/karim/32/4680_2.png) [@karim](https://forum.dfinity.org/u/karim) #### Post date: [March 24, 2024, 9:08am UTC](https://forum.dfinity.org/t/seo-will-using-custom-domains-alongside-the-canister-id-icp0-io-cause-duplicate-content-issues/28817/1 "2024-03-24T09:08:14Z")
When we set up custom domains either via the boundary nodes as described in the docs or via the service worker (the old approach), won’t this cause duplicate content issues? And if not: Can somebody explain why? My thinking always was that we should not have the same content on two domains and CANISTER\_ID.icp0.io obviously is a domain. Or does it do a 301 redirect, which would be the typical SEO way to solve this, if we follow [the docs for custom domains on boundary nodes](https://internetcomputer.org/docs/current/developer-docs/web-apps/custom-domains/using-custom-domains/#custom-domains-on-the-boundary-nodes)? ---
### Author: ![peterparker](https://avatars.discourse-cdn.com/v4/letter/p/b9bd4f/32.png) [@peterparker](https://forum.dfinity.org/u/peterparker) #### Post date: [March 24, 2024, 11:08am UTC](https://forum.dfinity.org/t/seo-will-using-custom-domains-alongside-the-canister-id-icp0-io-cause-duplicate-content-issues/28817/2 "2024-03-24T11:08:57Z")
Indeed, it’s might be indexed twice unless Google is clever enough to recognize it’s the same content. To prevent this issue, it’s best practice I think to add a `canonical` meta tag to your app/site. Example: ```auto ``` Documentation: > **[How to Specify a Canonical with rel="canonical" and Other Methods | Google...](https://developers.google.com/search/docs/crawling-indexing/consolidate-duplicate-urls)** > > When a site has duplicate content, Google chooses the canonical URL. Learn more about canonical URLs and how to consolidate duplicate URLs.