We Have Exchange 2010 environment,We have two CAS servers in the site with NLB configuration. Recently after patching ,one of the CAS servers started behaving erratically and would give password prompting errors etc ..despite escalating the call the problem was not resolved,Since then I have taken the CAS server out of the NLB. Now the CAS  is being serviced by a single server in the NLB cluster.

My requirement is bring back a new CAS server which will work as a standby just in case the existing CAS server fails.

What are my options ?

Is it possible to bring in a 3rd CAS server to the existing NLB ? if yes what is the procedure.

Please

Hello

I think search for error cas.
https://support.microsoft.com/en-us/kb/2634633
but if need new server:
uninstall "wrong" exchagne
install exch with same ru
install certificate
set internal/external url
add nlb member.

Can I bring in a new server as standby and then quckly ad the NLB if and when required? ..I do not want to reinstall on the old server

Hello

yes but if have nlb why not use it simple not need open any firewall and etc...

You can simply install a new CAS server and patch it up to the level of the "correct" CAS, but you have to be aware that as soon as the CAS is running, it could be queried by the clients for specific services. One example is Autodiscover, who - simplifying the discussion - will return for the Outlook clients a list of CAS servers in the same site, which the clients will use to connect to the specified AutodiscoverServiceInternalURI. You'll have to modify this to point to your NLB name, so that the new CAS isn't "used". Same goes for the OAB, ActiveSync, etc virtual directories.

Thanks Albert ..Wondering if you get shed some light on the commands I need to use to set AutodiscoverServiceInternalURI   . my current output of the get-ClientAccessServer -AutoDiscoverServiceInternalUri

Identity                       : HO-xx-01
AutoDiscoverServiceInternalUri : https://autodiscover.xx.com//Autodiscover/Autodiscover.xml

Identity                       : HO-xx-02 (This is the problematic CAS)
AutoDiscoverServiceInternalUri : https://autodiscover.xxt.com/Autodiscover/Autodiscover.xml

Identity                       : DR-xx-01
AutoDiscoverServiceInternalUri : https://autodiscover.xx.com//Autodiscover/Autodiscover.xml

-----------------------------------------

thanks 

Shiva

Hi,

Simply add third CAS server to NLB should works fine.
Please ensure that WebServices, Autodiscover and OWA, ECP virtual directory URL configuration on new CAS servers are identical to existing CAS servers in NLB.
If you cannot remove problematic CAS server, we can run below command to disable autodiscoveruri:
set-clientaccesserver -identity problemserver -autodiscoverinternaluri $NULL

To remove a host or all hosts from a Network Load Balancing cluster:
1. To open NLB Manager, click Start, click Administrative Tools, and then click Network Load Balancing Manager. You can also open NLB Manager by typing Nlbmgr at a command prompt.
2. If Network Load Balancing Manager does not list the cluster, connect to the cluster.
3. To remove a single host, right-click the host on which you want to disable Network Load Balancing, and click Delete Host.
More details about it, for your reference: https://technet.microsoft.com/en-us/library/cc733098.aspx

Thanks

Thanks ..one more question ..hardware wise the current model of the server will be different than the new server which I will be introducing ,will it be Ok ? I intend to use the same amount of memory as the live ones now ..

Will dissimilar hardware be OK ?

Hi,

Its OK.
Exchange 2010 System Requirements, for your reference:
https://technet.microsoft.com/en-us/library/aa996719(EXCHG.141).aspx

Thanks

Thanks