I presente my situation : I've just install a NLB on my cas array with 2 nodes. Since, this step, it impossible to access the CAS2 server's certificate from the CAS1 server. The cmdlet : Get-ExchangeCertificate -Server "CAS2", from the CAS1 server gave the error "Cannot connect to the RPC service on the server named CAS1. Verify that a valide computer name was used and the MES host service is started" I found some IPV6 DNS entries in my DNS, i don't knwo it is a DNS problem, but when i tried to access to the CAS servers's certificates from the others servers (MBX), there was no problem.

Either DNS or some ports got mucked up. Try to put a host file to eliminate the DNS resolution.James Chong MCITP | EA | EMA; MCSE | M+, S+ Security+, Project+, ITIL msexchangetips.blogspot.com

hi, According to the error, have you checked these services first: RPC/ MES host service on CAS1? Because you say:"but when i tried to access to the CAS servers's certificates from the others servers (MBX), there was no problem." So it seems that your issue is not caused by the NLB. Can you check your app log on cas1 to find more information? hope can help you thanks, CastinLu TechNet Community Support

Hi, How is your NLB configured? If you are running in Unicast-mode with a single NIC it's normal that you have no communication between your nodes. This is because, in unicast-mode, both nodes share the same MAC and the NLB cannot tell them apart. If that's the case, add a second NIC with a unique MAC and you should be fine. Cheers, MichaelMichael Van Horenbeeck Check out my blog or find me on twitter

Hi, How is your NLB configured? If you are running in Unicast-mode with a single NIC it's normal that you have no communication between your nodes. This is because, in unicast-mode, both nodes share the same MAC and the NLB cannot tell them apart. If that's the case, add a second NIC with a unique MAC and you should be fine. Cheers, MichaelMichael Van Horenbeeck Check out my blog or find me on twitter