Hi Ur0s,
The basic ADFS server farm is designed to give some redundancy, however based on your description I understand that you want to go a step beyond that.
Actually, there are a lot of solutions for setup the redundancy environment for ADFS server (including third party solutions), and most of them are using DNS or setup the server farm. I will give you some solutions for reference.
1. We can set up the multi-site ADFS environment for the redundancy solution. You can see detailed information here: http://community.office365.com/en-us/forums/613/p/80717/314956.aspx#314956
2. You can use SQL server instead of the WID (Windows Internal Database) and this can have high-availability features such as fail-over clustering or mirroring:
Federation Server Farm Using WID and Proxies
Federation Server Farm Using SQL Server
(Note that this topology does not provide database redundancy by default.)
3. Using SQL server, you can setup a high-availability solution across multiple data centers. Your SQL server would be mirrored from your datacenter to a DR (Disaster Recovery) datacenter. A network load balancer directs traffic between the two sites.
High Availability Solutions Overview
ADFS 2.0 High Availability and High Resiliency Walkthrough
In addition, since this is a separate ADFS deployment and administration question, I also want to suggest you create a new thread in the TechNet Windows Server forum, the staff in the forum above is devoted into the issues of AD and federation service relevant.
More information: http://social.technet.microsoft.com/Forums/windowsserver/en-US/80220b1c-d024-4f51-af9e-f38c4fe19c31/adfs-high-geo-redundancy?forum=Geneva
Thanks,
Bourne Zhang
