Hello, Below is my configuration: Microsoft Windows Server 2003, Enterprise Edition x64 - R2 Version 5.2.3790 ServicePack 2 Nu 3790 - Type x64 **** Microsoft Exchange Environnement: Exchange Server 2007 Microsoft Corporation - Version : 08.01.0263.000 --> In fact, I have 2 hubcas in NLB. I did turn off the HUBCAS1 and leave the HUBCAS2 online to check if everything will be up and running. The fact is that Mailflow did work all right (send/receive) but the Autodiscover and OWA did not work (mainly the OWA - could not authenticate the users). I check the ISA server and found the Even ID # 14200 (ISA Server failed to establish an SSL connection with %1. %2). Could you please tell me what went wrong and how I could fix the problem?? Thanks to all in advance. Graig

Hi, Did you create connectivity verifiers to validate connectivity with your OWA site? You can do this in the console of isa Server Management: - Click Monitoring - Click Connectivity tab - On the tasks tab click "Create New Connectivity Verifier" Check if there is a valid certificate on the target computer. Greetzz, Timmy

hi, you can look through this guides for help with troubleshooting the issue around ssl http://www.msexchange.org/articles_tutorials/exchange-server-2007/high-availability-recovery/load-balancing-exchange-2007-client-access-servers-windows-network-technology-part3.html http://blogs.msdn.com/b/brad_hughes/archive/2007/09/10/cas-load-balancing-certificates-autodiscover-and-webservices.aspx Hope it helps!

Hi, Please ensure the relevant services's internal URL on each CAS to be matched with NLB's name. And the authtication is consistent on each Virtual Directories between the two CAS servers. Thanks Allen

After analyzing the network, I found out that the NLB card on the second CAS/HUB was not receiving requests, (ARP request). The switch configuration showed that the NLB card was in a different NLB network than the other network. In the end, the issue was a network one and not an Exchange configuration. I wish to thank you all for your advices and I hope that thread could help. Graig