Greetings,

Exchange Server 2013 / Client Access Server is deployed in two sites

site 1: CAS1: Public IP 212.213.1.1 / Private IP 10.10.1.1

Site 2: CAS2: Public IP 212.213.2.1 / Private IP 10.10.2.1

EDGE1 deployed in Site1, EDGE2 deployed in Site2

How to achieve CAS availability across sites, i.e. if CAS1 Fails? is it enough to use DNS RR for both External and Internal CAS records? or it needs HW Load Balancers, and in this case, does the load balancer work for two CAS Servers even if they are in different sites?

Thanks

Hi

A hardware load balancer will be much better. you can use round robin if you dont have that avaialble. Your dns will point to the load balancer.

Ed,

does the HW Load balancer, balances load on two servers even if they are in two different sites?

Thanks

An HLB won't load balance between two sites, it would have to be a global load balancing solution. You could use round robin for the public DNS records to rotate between sites, it would be best to have load balancers with the proper probes setup at each site to mark a server as unresponsive or not if OWA is down for some reason. 

An HLB won't load balance between two sites, it would have to be a global load balancing solution. You could use round robin for the public DNS records to rotate between sites, it would be best to have load balancers with the proper probes setup at each site to mark a server as unresponsive or not if OWA is down for some reason. 

• Marked as answer by Simon_WuMicrosoft contingent staff, Moderator Friday, February 06, 2015 2:11 PM

Hi,

 Which HLB you are referring too ?. We had same issues, when we try to setup Citrix HLB we got failed.

Hence, please give me a recommendations to fix it?