You try to access an RSS (Really Simple Syndication) feed that points to a resource that requires authentication. (The RSS feed is located on the same Web site as the resource.) After you do this, you receive the following error message in Microsoft Office SharePoint Server 2007:
The RSS webpart does not support authenticated feeds
This issue occurs if there is a CNAME record for the SharePoint server and if the record points to an alias that does not have a registered Service Principal Name (SPN).
This issue occurs if you use NTLM authentication for the RSS feed instead of one of the following authentication methods:
To resolve the issue, use the resolution that is appropriate to the cause.
To resolve this issue, you must create a CNAME record that points to a name that has a registered SPN. To do this, follow these steps.
Check the registered SPNs for the SharePoint server
On a domain controller that has the Windows Support Tools installed, open a command prompt.
At the command prompt, type the following command, and then press ENTER:
Setspn –l Hostname_of_SharePoint_Server
In the list that is displayed, locate the entry that corresponds to the following entries: