How often can one make a change in Development that blows up Production? Within the User Profile Service Application one can configure the MySite Host Location. However watch out, as I made a change in a Dev environment that propogated and affected all Production users.
In Dev, I set the Trusted Host Location without setting a target audience. This broadcast to all farms (including Production) that this location should be the default. Users attempting to go to their MySite were instantly redirected to Dev! Of course DNS and Production didn’t offer a clue. Removing the Trusted Host location in Dev eliminated the problem.
In a related annoyance, the My Site Host location in Setup MySite defaults back to the Default Zone for the MySite web app. With AAM set up correctly, it will change any entry back to the default zone. So to change the MySite Host Location, it seems I’ll need to rebuild the web app with the desired default MySite URL. Not too convenient since I have quite a few Web App custom settings such as Maximum file upload size and Super User Publishing Cache account definitions.