Under what conditions is Apple's 'advertisingIdentifier' reset?

Question

Other than the user manually resetting it, has anyone observed other things that will cause the ADID to be reset? OTA OS Upgrades? iTunes Restores?

Answer 1

Two cases:

• Manually choosing “Reset Advertising Identifier”. But if the app is running in the background, the identifier will remain active until the application is relaunched.
• Manually choosing “Reset All Content and Settings”.

Backups, OS upgrades, app re-install, or choosing “Limit Ad Tracking” won't reset the identifier.

AFAIK you could send the vendor ID and the advertising ID to the server, and when the user resets the advertising ID with “Reset Advertising Identifier”, you can match the new with the old one, because the vendor ID survives. No idea how Apple intends to prevent this.