DNS Record Change for Exchange Failover

We are looking to configure\fine tune our Exchange 2010 failover scheme. Currently we have a cas array (via a Kemp Load balancer) in production by the name of CAS00. CAS00 is the RPC server for all of our local Outlook clients.

We also have a CAS server in our disaster recovery site by the name of CAS03. We are thinking, when CAS00 in production goes down, we can manually change the DNS A record of CAS00 to point to the IP address of the DR Cas server. This way the clients still point to the CAS00 RPC server but the DR server is actually handling the exchange requests.

I was told something about creating a cname record that points record to tie into the failover scheme which would have a shorter TTL than the A record to create some sort of DNS redundancy and make the process more automated.

Can anybody shed any light as to how to accomplish this?
GR JNAsked:
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piwowarcConnect With a Mentor Commented:
Hello

DNS is not "state aware" load aware mechanism. You can't achieve any failure aware system that would automatically failover to DR server. For that you need actual load balancer.

Active Load Balancing can be achieved with DNS actually. IT is frequent for high traffic and reslient deployments (do nslookup of google for ex). If you give all servers behind this Kemp LB same name, DNS will return addresses to users at random achieving load sharing. It will still be a bit worse that actual LB you have as it will still give IPs of servers that may have gone down.

In general Load Balancers are way better to do any auto failovers than using DNS.

Regards
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MaheshArchitectCommented:
Yes, you have to change the DNS Record for the CAS Array name in DNS in order to route all connections to the DR CAS Server

Mahesh
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GR JNAuthor Commented:
Yes, I know that but is it just the A record or can we tie in a cname record as well?
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MaheshArchitectCommented:
Cname record is not required

You need to point your existing  CAS server \ CAS Array Host(A) record to DR CAS server

http://social.technet.microsoft.com/Forums/exchange/en-US/704695d4-dfb2-40dd-ad58-46b34dc1aa38/exchange-2010-site-resiliency-cas-array-failover?forum=exchange2010

Mahesh
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GR JNAuthor Commented:
wa
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