Merge pull request #6862 from segmentio/prigiattiperrut-patch-4

Update custom-domain.md

Author: forstisabella

src/connections/sources/custom-domain.md

@@ -94,3 +94,7 @@ Segment also uses AWS Certificate Manager (ACM) to manage and renew certificates
 Yes, Custom Domain allows Segment to rename `window.analytics` to a unique name to avoid being blocked by some ad blocking software. 
 
 Customers who have access to the Custom Domain feature can rename analytics to `<workspaceid>/<sourceid>.js` by choosing an Alias for Analytics.js within the source settings that are available after the workspace is enabled for Custom Domain. 
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+### What happens to the Analytics.js cookies already set on the user's browser prior to a Custom Domain implementation?
+Analytics.js cookies are not lost in the transition to Custom Domain. When users revisit your website, the previous Analytics.js cookies continue to be fetched and added to events, if available.
+