We have an AD domain with FQDN domain.local
Using split-dns for our domain contoso.com

Questions 1)
Currently we have setup Exchange 2010 as in image below, is this a Ambiguous URL scenario?
(I think not because the CAS array FQDN is different)

Question 2a)
Cause we can utilize split-dns we use same internal and external URL (internal DNS points to Exchange and external DNS points to reverse prxoy), is this supported/best practise and is this done by more people?

Question 2b)
What will be pro and cons for this setup (sharing same URL internal and external)?

Question 2c)
Why would/should we go for different external and internal URL?

Question 3)
If we use same URL internal and external, how does "Exchange" know if we hit the internal or external URL (does it look at source IP)?

No, that is not ambiguous.  there is a separate name space for RPC client access.

Yes use split dns.

Having different internal and external URLs is more complicated and confusing. Why should users  care about an Owen URL for internal access and a separate one for  external....

That's  also the client interaction too.  if the name resolves, outlook uses internal.

Hi Rhoderick,

Thanks for the quick reply.

All clear now :-)

Last question, I see on lot of blog post on team exchange blog different URL for EWS, OWA etc.

What would be the purpose of this and why no use one url there also as we have now?

Regards.

Few reasons.  Allow splitting of traffic for management purposes.  Allows different affininty options per VIP.....

Hi. For Split DNS i'm always check. 

1. Get-ClientAccessArray | fl

New-ClientAccessArray -fqdn "mail.domain.com" -Site "Default-First-Site-Name"

Set-MailboxDatabase -RPCClientAccessServer mail.domain.com

Get-MailboxDatabase | Set-MailboxDatabase -RPCClientAccessServer mail.domain.com

2. I'm always check: Get-OutlookProvider 

Set-OutlookProvider -Identity EXPR -CertPrincipalName msstd:mail.domain.com
Set-OutlookProvider -Identity EXCH -CertPrincipalName msstd:mail.domain.com

In DNS create zone domain.com and A record: mail.domain.com (ip addresses NLB or WinNLB or DNS RR), autodiscover.domain.com (ip addresses NLB or WinNLB or DNS RR).