You design a Business Intelligence (BI) solution by using SQL Server 2008. The solution includes reports hosted on a single SQL Server 2008 Reporting Services (SSRS) server. You plan to modify the report server infrastructure to support a scale-out deployment. You need to ensure that the scale-out deployment meets the following requirements:
-Allows users to access any of the Report Server servers by using the original Report Manager URL.
-Minimizes network traffic.

Which three tasks should you perform? (Each correct answer presents part of the solution. Choose three.)

A.
Add a <HostName> element in the <Service> section of each RsReportServer.config file.

B.
Add the same <machineKey> element in the <system.web> section of all web.config files for each Report Server server.

C.
Add a different <machineKey> element in the <system.web> section of all web.config files for each Report Server server.

D.
Modify the <UrlRoot> element in the <Service> section of each RsReportServer.config file.

E.
Modify the <ReportServerUrl> element in the <UI> section of each RsReportServer.config file.

F.
Modify the <sessionState> element in the <system.web> section of the web.config file in each ReportManager folder.

Explanation:
Tip: "network traffic" = "<HostName>" / "same <machineKey>" / "<UrlRoot>"

http://msdn.microsoft.com/en-us/library/ms156453(SQL.90).aspx
Configuring a Report Server Scale-Out Deployment
A scale-out deployment refers to an installation configuration that has multiple report server instances sharing a single report server database.
Configuring View State Validation
– Open the Web.config file for Report Manager and set the <machineKey> element. You must specify the validation key, decryption key, and the type of encryption used for validation of data.
– Repeat these steps for each report server in the scale-out deployment. Verify that all Web.Config files in the Reporting ServicesReport Manager folders contain identical <machineKey> elements in the <system.web> section.
Specifying the Virtual Server Name in Reporting Services Configuration files
If you configure the report server scale-out deployment to run on an NLB cluster, you must manually update report server URL settings in the configuration files to use the virtual server name.
– Set the <ReportServerUrl> to the virtual server name and remove the entry for <ReportServerVirtualDirectory>. This step ensures that all requests coming through Report Manager are load-balanced to the report servers that are running in the scale-out deployment.
– Set the <UrlRoot> to the virtual server address. This step ensures that all hyperlinks in reports point back to the scale-out deployment and are load-balanced accordingly. This setting is also used to complete report delivery.

http://msdn.microsoft.com/en-us/library/ms157273.aspx
RSReportServer Configuration File
The RSReportServer.config file stores settings that are used by Report Manager, the Report Server Web service, and background processing. All Reporting Services applications run within a single process that reads configuration settings stored in the RSReportServer.config file.
Service section specifies the application settings that apply to the service as a whole. For more information about the internal components of the service.
UrlRoot – Used by the report server delivery extensions to compose URLs that are used by reports delivered in e-mail and file share subscriptions. The value must be a valid URL address to the report server from which the published report is accessed. Used by the report server to generate URLs for offline or unattended access. These URLs are used in exported reports, and by delivery extensions to compose a URL that is included in delivery messages such as links in e-mails.
The report server determines URLs in reports based on the following behavior:
– When UrlRoot is blank (the default value) and there are URL reservations, the report server automatically determines URLs the same way that URLs are generated for the ListReportServerUrls method. The first URL returned by the ListReportServerUrls method is used. Or, if SecureConnectionLevel is greater than zero (0), the first SSL URL is used.
– When UrlRoot is set to a specific value, the explicit value is used.
– When UrlRoot is blank and there are no URL reservations configured, the URLs in rendered reports and in e-mail links are incorrect.