We are looking to setup a three node PKI infrastructure, all running Server 2012 r2: Standalone Root CA (not in the domain) and 2 Enterprise Subordinate CA's (in the same domain. We already have the root CA and one of the enterprise CA's deployed and it's working great. We would like to add a 2nd enterprise CA so that when the first enterprise CA is not available it can still respond to certificate requests; however, I'm not able to find much online documentation for doing such a thing. The 2 enterprise CA's would essentially be at the same level on the domain and when both are running, either one could respond to requests. Can you provide me with any documentation on doing this or have any steps/recommendations for accomplishing this task?