CDN is provided only for Q releases, Beta releases and SP releases.
You are using an internal build, which does not have CDN. To resolve this issue, you need to upgrade either to official release, or disabled the CDN. Disabling the CDN happens either in the web config or per page settings (depends on your actual case).
For the various settings available for the CDN you can check the following help topic -- http://www.telerik.com/help/aspnet-ajax/scriptmanager-cdn-support.html
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