I need some help and explanation as to why I need multiple different name spaces for Exchange 2010-2016 co existence ?
With an Exchange 2010 site-resilient design, you needed up to eight different namespaces:
two Internet Protocol namespaces
two for Outlook Web App fallback
one for Autodiscover
two for RPC Client Access
one for SMTP.
My AD domain is just single forest domain.com so what are the best suggested name to choose ?