Is IIS caching DFS referrals under a different context to my local user account?

We're migrating the main media store for our website to a new server. I'm investigating using distributed file system (DFS) to do this, so that instead of replacing all the hard-coded references to \\oldserver\media with \\newserver\media in our website code and config files, I can:

1. Set up \\mydomain.com\dfs as a DFS share
2. Add a media folder to that DFS share, with a target pointing at \\oldserver\media
3. Update all my code and config files to use \\mydomain.com\dfs\media instead of \\oldserver\media

and then when that's all done, add a DFS target of \\newserver\media\, remove the \\oldserver\media target, and (theoretically?) my web servers will then start finding the new server instead of the old one when following that media share.

Nice theory. Doesn't work. Right now, if I go to \\mydomain.com\dfs\media from my workstation in Windows Explorer, I can see the NEW server (which is correct), but virtual directories in IIS that are mapped to \\mydomain.com\dfs\media are still seeing content on the OLD server.

What's bizarre is that the DFS configuration on the domain controller doesn't even have a reference to the old server any more - I've removed the target, and done a dfsutil cache domain flush and dfsutil cache referral flush on my workstation.

Is my local machine maintaining a separate referral cache that's used by IIS but not by Windows Explorer? Is there some other resolution mechanism that could explain why different processes on the same host are seeing different results?