Exchange Server 2010 : Managing Web and Mobile Access (part 1) - Enabling and Disabling Outlook Web App Features, Configuring Ports, IP Addresses, and Host Names Used by Web Sites

IIS handles incoming requests to a Web site within the context of a Web application. A Web application is a software program that delivers content to users over HTTP or HTTPS. Each Web site has a default Web application and one or more additional Web applications associated with it. The default Web application handles incoming requests that you haven't assigned to other Web applications. Additional Web applications handle incoming requests that specifically reference the application.

When you install a Client Access server, virtual directories and Web applications are installed to support various Exchange services. Each Web application must have a root virtual directory associated with it. The root virtual directory sets the application's name and maps the application to the physical directory that contains the application's content. Typically, the default Web application is associated with the root virtual directory of the Web site and any additional virtual directories you've created but haven't mapped to other applications.

In the default configuration, the default application handles an incoming request for the / directory of a Web site as well as other named virtual directories. IIS maps references to / and other virtual directories to the physical directory that contains the related content. For the / directory of the default Web site, the default physical directory is %SystemRoot%/inetpub/wwwroot.

In most cases, you only need to open port 443 on your organization's firewall to allow users to access Exchange data hosted by IIS. Then you simply tell users the Uniform Resource Locator (URL) that they need to type in their browser's Address field or in their smart phone's browser. Users can then access Outlook Web App or Exchange ActiveSync when they're off-site. The URLs for Outlook Web App and Exchange ActiveSync are different. The Outlook Web App URL is https://yourserver.yourdomain.com/owa, and the Exchange ActiveSync URL is https://yourserver.yourdomain.com/Microsoft-Server-ActiveSync. Generally, however, the address users enter for both matches the OWA address.

You can configure Outlook Web App and Exchange ActiveSync for single-server and multi-server environments. In a single-server environment, you use one Client Access server for all your Web and mobile access needs. In a multiple server environment, you could instruct users to access different URLs to access different Client Access servers, or you could use a technique such as Round Robin Domain Name System (DNS) to load-balance between multiple servers automatically while giving all users the same access URLs. However, for optimal scalability and availability, you should configure a Client Access server (CAS) array and then use a software or hardware load balancer.

You can use Outlook Web App and Exchange ActiveSync with firewalls. You configure your network to use a perimeter network with firewalls in front of the designated Client Access servers and then open port 443 to your Client Access servers or to the URL for the CAS array.

When you install a Client Access server, Exchange Setup installs and configures virtual directories and Web applications for use. The virtual directories and Web applications allow authenticated users to access their messaging data from the Web. In the Exchange Management Shell, you can use the Get-OWAVirtualDirectory cmdlet to view information about OWA virtual directories, the New-OWAVirtualDirectory cmdlet to create an OWA directory if one does not exist, the Remove-OWAVirtualDirectory cmdlet to remove an OWA directory, and the Test-OWAConnectivity cmdlet to test OWA connectivity. There are similar sets of commands for ActiveSync, Autodiscover, ECP, OAB, Windows PowerShell, and Web services. If you examine the virtual directory structure for the default Web site, you'll find several important virtual directories and Web applications, including

This section examines key tasks that you use to manage IIS, virtual directories, and Web applications.

Microsoft uses the term segmentation to refer to your ability to enable and disable the various features within Outlook Web App. Segmentation settings applied to the OWA virtual directory on Client Access servers control the features available to users. If a server has multiple OWA virtual directories or you have multiple Client Access servers, you must configure each directory and server separately. Table 1 provides a summary of the segmentation features that are enabled by default for use with Outlook Web App.

You can enable or disable segmentation features by completing the following steps:

In the Exchange Management Shell, you can enable or disable segmentation features using the Set-OWAVirtualDirectory cmdlet. To enable or disable these features for individual users, use the Set-CASMailbox cmdlet.

Each Web site hosted by IIS has one or more bindings. A binding is a unique combination of ports, IP addresses, and host names that identifies a Web site. For unsecure connections, the default port is TCP port 80. For secure connections, the default port is TCP port 443. The default IP address setting is to use any available IP address. The default host name is the Client Access server's DNS name.

Normally, you won't want to multihome a Client Access server. However, when the server is multihomed, or when you use it to provide Outlook Web App or Exchange ActiveSync services for multiple domains, the default configuration isn't ideal. On a multihomed server, you'll usually want messaging protocols to respond only on a specific IP address. To do this, you need to change the default settings. On a server that provides Outlook Web App and Exchange ActiveSync services for multiple domains, you'll usually want to specify an additional host name for each domain.

When you are working with IIS 7.0 or IIS 7.5, you can change the identity of a Web site by completing the following steps: