Hi all, I'm going to add a new CAS to my infrastructure with Exchange Server 2010 SP2 to provide redundancy for this in fact. I have seen reading on the net that the best way to do this is through NLB. My question, however, is whether there is a proper procedure to be used not only to configure NLB but also to add the new CAS and correctly to ensure that if one of them is down the other is always able to process the requests. Thank you,

You need to configure a CAS Array and then configure Windows NLB /Hardware NLB with a virtual IP. Refer the blog which will give the step by step activity. http://howtoexchange.wordpress.com/2009/12/16/configuring-client-access-array-for-exchange-2010-walkthrough/Shaba

Actually, WNLB is only recommended when you do not have a hardware or 3rd party software load balancer. Having said that, its better than nothing! Since you apparently do not have a CAS Array defined now, you have two hurdles to leap once you create it. 1. Once you define the CAS Array, you will need to define it on the mailbox stores of course. 2. The Outlook clients however will not reflect the RPCClientAccess change name in their profiles unless they create new Outlook profiles or modify them and do a "Check Name". More info on load Balancing with 2010: http://technet.microsoft.com/en-us/library/ff625247.aspx Understanding Load Balancing in Exchange 2010

Thank you both for the reply. Luca