Hi, I have installed exchange 2007 with clusterd mailbox role (SCC) and another server with client access and hub transport roles. And now want to install another server with client access and hub transport roles for redundancy, can I just install this two roles or I should configure network load balancing for this new server or what? How to install this aditional server with this two roles, what is the best practice?

Hi, The HUB transport role will be load balanced automatically (I assume that you install in the same site), but if you want the CAS server role to be load balanced you need to use NLB. See also: http://forums.microsoft.com/TechNet/ShowPost.aspx?PostID=1865090&SiteID=17 Leif

What if I just install two CAS into my environment without LB, is it posible or they must be in LB?

Hi, I guess that it depends what you are using the servers for. These are used for RPC over http, POP3, IMAP4, OWAand active-sync. Internally AD and DNS should help the clients to find the servers, but if you want to access the environment from the outside and you have only one IP address you need to nlb to get fault tolerance. Leif