We have two ADFS servers in different data centers. I've tested I can connect to them both externally by changing my local host file, no problem. I'm trying to set up Azure Traffic Manager for failover from the primary site to the secondary. Under configuration --> for the path --> is it fqdn/adfs/ls/idpinitiatedsignon.aspx ? Or adfs/probe?
I'm not finding much information on it.
Internally I can browse fqdn/adfs/ls/idpinitiatedsignon.aspx but when I try adfs/probe, I receive a blank page.
You should use adfs/probe. It listens on TCP 80 so this must be open. Be aware if you want full redundancy (in case of both WAP or ADFS backend failure) you need to use a workaround in your Azure Traffic Manager (or AWS Route 53) and your WAP configuration. You find the workaround here: http://skrubbeltrang.com/fault-tolerant-adfs-setup/