There is a known issue with Microsoft Hotfix KB979683
The behavior I experienced was pretty strange, mainly:
- When I added the DNS A Record for the MDS-IS service, I could no longer sign into the Blackberry Administration Console using Active Directory Authentication. I could only use BAS Authentication ... but i was able to access the configuration for the MDS-IS Component
- When I removed the DNS A Record for the MDS-IS service, I was able to sign in via AD Authentication but was unable to configure the MDS-IS Component
- Numerous error messages were displayed from timezone issues to message routing problems
- BES would stop redirecting email after 6 - 8 hours depending on load
Removal of the Hotfix appears to have cured all these issues and more.
Thanks to the Blackberry Support Community Forums for pointing me in the right direction, specifically this post