The telnet tool (on the Advanced > Troubleshooting page) can be used to test connectivity. The Barracuda unit should be able to connect to update01.barracuda.com on port 80 (you would enter update01.barracuda.com 80 and click the Begin Telnet button). Check the output in the pop-up window to see if it's able to connect. If not, some device on your network is likely locking the connection.
If a proxy server or filtering device is configured to monitor port 80, please either exclude the Barracuda unit from the content filtering or provide the Barracuda unit with the correct proxy information on the Basic > IP Configuration page.
Ensure if there is a configured username or password for the proxy, that they are correct
Set DNS force local to yes or toggle it off/on to see if this changes any outcome in DNS resolution
Please contact Barracuda Technical Support if the problem persists.
Link to This Page: http://www.barracuda.com/kb?id=50160000000GSXO