How to Deploy Options for Exchange Server 2013

          Exchange Server 2013 is available in both the Standard Edition and Enterprise Edition.
          Standard Edition: should meet the messaging needs of most small and medium corporations, but it also may be suitable for specific server roles or branch offices.
          Enterprise Edition: designed for large enterprise corporations, enables you to create additional databases, and includes other advanced features.
          The main difference between Standard and Enterprise versions is that Enterprise version supports up to 50 mailbox databases while with Standard version you can create up to five databases. The version used is determined by product key that you enter when activating your Exchange installation.
          Exchange Server Standard CAL: This license provides access to email, shared calendaring, Outlook Web App, and ActiveSync.
          Exchange Server Enterprise CAL: This license requires a standard CAL, and provides access to additional features such as unified messaging, per-user and per-distribution-list journaling, managed custom email folders, and Microsoft Forefront Endpoint Protection for Exchange Server.
          Single server deployment: We deploy both Exchange Server roles on a single server. This is appropriate for small organizations with limited resources. Deploying all Exchange Server services on a single server has several drawbacks. It is recommended that you deploy Exchange Server inside a virtual machine, and that you keep that virtual machine highly available or at least replicated to another Hyper-V in Windows Server 2012 host. This will provide you with high availability and redundancy for critical Exchange services.
          Multiple server deployment: We usually install the Client Access Server role and the Mailbox server role on separate servers, or you install more than one server with both roles installed. This requires that you provide at least two virtual or physical machines for the Exchange Server deployment. In scenarios where you also want to provide high availability, you should add more machines to build the Client Access load balancing cluster and DAGs. You cannot use DAGs and network load balancing (NLB) on the same set of machines. To achieve full redundancy for Exchange Server, you need at least four servers for Exchange, and at least two domain controllers.
          Hybrid deployment: Provides the ability to extend on-premises Exchange Server
functionality to the cloud.You connect your AD DS and Exchange Server with Microsoft Office 365. This allows you to move some of your Exchange resources to Office 365. A hybrid deployment also can serve as an intermediate step prior to moving completely to an Exchange Online organization.