Hi,

In my current environment I have 2 Exchange 2010 servers with DAG no CAS NLB. I installed Exchange 2013 with 2 CAS with WNLB and 2 Mailboxes with DAG. The main requirement is to configure Single name space to access in between Exchange 2010 and Exchange 2013. On Exchange 2010 DAG there is a URL using is owa.domain.com and I also configured in Exchange 2013 all the virtual directories with this name owa.domain.com but having an issue that when I open explorer and use the owa.domain.com URL the user on Exchange 2013 gets their mailbox but user on Exchange 2010 gets error HTTP 403 blank page.

I observed that in Exchange Organization settings CAS settings one server OWA, ECP etc shows their internal external URL but the other server unable to open the OWA, ECP URL and give error message that "An IIS directory entry couldn't be created. The error message is Access is denied. HResult = -2147024891"

Please guide how to resolve this issue and use the same name URL in Exchange 2010 and Exchange 2013

Thanks, 

Hi,

See the below brief:

User will connect to mail.contoso.com as his namespace endpoint. CAS2013 in Site1 will authenticate the user, do a service discovery, and determine that the mailbox version is 2010 and is located within the local AD site. CAS2013 will proxy the request to an Exchange 2010 Client Access server which will retrieve the necessary data from the Exchange 2010 Mailbox server

Go through the full blog for better understanding of the redirection.

Client Connectivity with Exchange 2013

Hope you have changed your DNS records to direct connections only to your new Exchange 2013 server. You'll move the host names (for example, mail.contoso.com) users have been using to connect to Outlook Web Access, Autodiscover, and so on, from your Exchange 2010 server to your Exchange 2013 server. When an Exchange 2010 user tries to open their mailbox, the Exchange 2013 server will proxy their request and communicate with the Exchange 2010 server on their behalf.

• Change the primary host names, such as mail.contoso.com, autodiscover.contoso.com, and owa.contoso.com (if used) to point to the external, publically-accessible, IP address of the Exchange 2013 Client Access server with your public DNS provider.

• Change the primary host names, such as mail.contoso.com (or internal.contoso.com if you're using different internal host names) and owa.contoso.com (if used) to point to the internal machine name of the Exchange 2013 Client Access server on your internal DNS servers.

NOTE- Go through the Exchange Deployemnt Assitant - Configure DNS Records s

Also check This.

OWA redirection and SSL offloading fail after you install an Exchange Server service pack

https://support.microsoft.com/en-us/kb/2839692

Hello Satyajit,

Thanks for your input and I have already strived all these steps but unfortunately could not fix the issue. I want to fix the issue on my second Exchange 2010 server where the OWA, ECP URL field showing null entry and couldn't allow me to enter the URL and giving the IIS directory error which I have mentioned above.

Please guide to resolve the problem.

Thanks

Hi Lucky,

You IIS directories might be corrupted. Try these with caution.

Reset Client Access Virtual Directories

Hi,

As Satyajit mentioned, please try to empty the virtual directory setting in Exchange 2010. The command as below:
Set-AutodiscoverVirtualDirectory Identity ExternalUrl $Null InternalUrl $Null
Set-EcpVirtualDirectory Identity ExternalUrl $Null InternalUrl $Null
Set-OwaVirtualDirectory Identity ExternalUrl $Null InternalUrl $Null
Set-WebServicesVirtualDirectory Identity ExternalUrl $Null InternalUrl $Null
Set-OABVirtualDirectory Identity ExternalUrl $Null InternalUrl $Null
Set-ActiveSyncVirtualDirectory Identity ExternalUrl $Null InternalUrl $Null
Note: please point all DNS and MX record to Exchange server 2013, instead of Exchange 2010.

Thanks