Although I've read a few posts from people with the same problem as me, I couldn't find any solutions that would work for us.
The problem is that corporate laptops had the IE home page set to our intranet. When laptop users disconnected from the corp network went home, some users would experience a random redirect to a parked domain page, (or in some cases gambling websites?!), since the intranet is obviously not available when not connected to the corp network.
To get round this issue, we set the IE homepage from http://intranet
(where we have split brain DNS with an internal company.com zone). On the public DNS servers, we set a redirect for intranet.company.com to the corporate web site.
This works in as much as users get the intranet when connected to the corp network, and are redirected to the corp web site when not connected to the corp network. However... Internet Explorer 9 (and other browsers) appear to be caching the redirect from external DNS servers, and when users reconnect to the corp network and open IE, they get the corp web site rather than the intranet, since IE 'remembered' the redirect!
1) Does anyone know a work around to stop IE from remembering the redirect?
2) I'm thinking of using GPO to set the IE homepage to the intranet, so that when users login to the corp network, they get the correct intranet home page. But I'd then also need a way of having IE default to the corporate web site when the users are not on the corp network and GP is unavailable. How could this part work?