Based on your description, it would appear that NLB is not working properly. I’ve discussed the process for configuring NLB at http://blogs.kraftkennedy.com/index.php/2009/11/25/configuring-nlb-for-exchange-2010-cas-load-balancing/ but there are also a few other articles on the Internet for how to configure this properly.

Whenever I open Outlook, I got error…”The set of folder can not be opened…”

Frank- If you are using NLB as your method of load balancing, yes, you would need to enable IP forwarding via netsh if you are using multiple NICs. I discuss this in more detail in my post on NLB and Exchange 2010 CAS load balancing at http://blogs.kraftkennedy.com/index.php/2009/11/25/configuring-nlb-for-exchange-2010-cas-load-balancing/.

Thank you so much for your input.

To give you a better picture.

- a forest with multiple domain.
- Root forest in France, there is a Exchange 2007 installed
- two sub domains, UK and Germany also have Exchange 2007 installed

Recently install Exchange 2010 on Asia domain with
- 2 x hub/cas roles (configure for NLB)
- 2 x mailbox role (configure for DAG)

There is no exchange server deployed in Malaysia and other Asian AD site, Singapore Exchange 2010 will provide email for Malaysia, Brunei, Indonesia, etc…
All AD site have their own email domain.
- domainmalaysia.com
- domainbrunei.com, etc…

All these domains will be accepted by the Exchange Server.

Correct me if I am wrong, is the procedure like this

1. user in AD site malaysia launch outlook 2007, if he is joined to the domain, the email address (user@domainmalaysia.com) will be filled automatically.
2. this will queries the autodiscover.domainmalaysia.com right?
3. then it will get all the exchange server name (should be the NLB if it is set up correctly)

Here is my questions

1. Do I have to created autodiscover DNS record in all AD Site?
2. We have to point (e.g.autodiscover.domainmalaysia.com) to be able to reach the clientAccessArray IP address right?
3. And the certificate SAN name must also include all accepted email domain above?

Thanks for the feedback.

Do you have Exchange 2010 servers also deployed in the Malaysia AD site such that you are asking how to ensure that users hosted in that site are referred to an appropriate CAS server in that site? Or is Exchange only in the Singapore AD site and you are asking about users in the Malaysia site accessing Exchange in the Singapore site?

If it’s the former, you would point the Internet Autodiscover record to your largest data center (e.g. Singapore) and then configure the ExternalUrls for your various CAS virtual directories in Malaysia. When a Malaysia user queries Autodiscover (in Singapore) for an Exchange service, Autodiscover will determine the best CAS for that user to be in Malaysia and return the proper ExternalUrl (for Outlook Anywhere, ActiveSync, etc.) or InternalUrl (for Outlook RPC) for CAS in the Malaysia site.

If it’s the latter, then you don’t need to do anything special. Since your Exchange infrastructure is consolidated in Singapore, that is where your users would access CAS services and, therefore, Autodiscover will return information from that site appropriately.

Alternatively, if you’re asking how to make Autodiscover leverage the CAS Array you’ve created, you can change the Autodiscover Internal URL value via “Set-ClientAccessServer -Identity -AutoDiscoverServiceInternalUri: https://cas.singapore.domain.com/Autodiscover/Autodiscover.xml” for each CAS server in the Singapore site. However, if you change this value, make sure that you add the CAS Array FQDN as a Subject Alternative Name on your installed SSL certificate.

I hope this helps.

I have a scenario now and i sincerely hope you can help me.
A forest with multiple domains and i have an exchange server 2010 in Singapore with 2 hub/cas in a NLB and 2 mailbox servers. And these Exchange servers serves the Asia Pacific region users from different AD site. i have created a new array:
new-ClientAccessArray -name SingaporeCAS -fqdn cas.singapore.domain.com -Site Singapore

However, I have Malaysia AD site (and others), what do i need to do so that they can those users can point to the server for autodiscover and automatically map those users at Malaysia to the CAS array server?

Thank you.

In my comment, I was referring to the case where CAS and MBX were separate and the CAS selection would be random. I almost always co-locate HTS/CAS on the same servers and separate out MBX unless there is a specific client need/limitation that requires all roles on the same server(s).

You are absolutely correct that, if you co-locate CAS and MBX on the same server, the local CAS would be chosen.

I’m not aware of anything special that needs to be done other than setting the RPCClientAccessServer attribute as per the instructions in this post. If you don’t set this attribute yourself, a random CAS will be used for this attribute and this would cause access issues if this CAS is ever unavailable. Thus, even if you have only one CAS in your environment, it makes sense to leverage a ClientAccessArray and the RPCClientAccessServer attribute in case your environment grows in the future.

If you do come across any additional information, please let me know.