I have to upgrade a customer Exchange 2010 environment to 2013 and during the investigation of customer's current 2010 environment I noticed that the namespace was configured with same URL for CAS Arrays and internal HTTPS services which introduces a serious problem with co-existence as stated in this article (http://blogs.technet.com/b/exchange/archive/2013/05/23/ambiguous-urls-and-their-effect-on-exchange-2010-to-exchange-2013-migrations.aspx)
This article advices to change the cas array to a unique name that is only resolvable in internal DNS and change RPC endpoint in databases and force all Outlook clients to connect Internally with https to prevent problems before introducing Exchange 2013 servers to organization.
My question is that if I introduce a completely new namespace to Exchange 2013 will this Ambiguous URL problem affect the deployment. Let's say that the old environment uses exchange.company.com in internal HTTPS and CAS Array and webmail.company.com as external namespace. If I install Exchange 2013 to organization and configure it to use new mail.company.com namespace will I be able to prevent this issue? Of course introducing a new namespace means new URLS for OWA and ActiveSync etc but in this particular case it would be easier approach.
