Hi All,
I woke up to a very random issue today where one of my CAS/HUB server stopped communicating with one of my mailbox servers. My site consists of 2x CAS/HUB servers (CAS1 & CAS2) and 3x Mailbox servers (MB1, MB2, and MB3).
CAS2 has no issues communicating with all three mailbox servers and CAS1. However, CAS1, can only communicate with MB2, MB3, and CAS2. ALL AD, DNS, IP, and Firewall has not changed and have been triple checked from all servers and all tested fine...Rebooted
all Servers, all services start up fine, and no real errors in the event log.
After much troubleshooting, the issue seems to be that CAS1 cannot establish communication with MB1 and vice versa due to certificate trust issue. From CAS2, MB2, and MB3, I can run "get-exchangecertificate" and get a correct output for all Exchange servers. Furthermore, when using EMC via CAS2, MB2, and MB3, I can see the exchange certificate under "Server Configuration". But from either CAS1 or MB1, if I run the same command to pull data for either server or run EMC, neither server can pull certificate information for the other, but again, they can pull for CAS2, MB2, and MB3.
So long story short, CAS1 and MB1 cannot communicate with either to pull certificate trust to establish a connection but can do so with with all other exchange servers. The common error is "remote procedure call" failed.
I'm stuck...