What is my Barracuda NG Firewall having trouble resolving URLs while using HTTP proxy?

The Proxy needs a DNS-Server to resolve the URLs. There are 2 ways to configure a DNS-Server for the Proxy-Service.

Configure the DNS-Server in the Box-Settings:

1. Navigate to Config > Box > Administrative Settings > DNS Settings
   
2. Set a DNS-Server in the DNS Server IP list.

3. Set the option in Run Forwarding/Caching DNS Config to No.

4. Restart the Proxy-Service.

Configure the DNS-Server in the advanced configuration of the proxy:

This option should only be used if the proxy will use another DNS-Server as the box itself.

1. Navigate to Config > Box > Virtual Servers > <Servername> > Assigned Services > <Servicename> > HTTP Proxy Settings > Advanced
   
2. Set the option dns_nameservers.
1. dns_nameservers 192.168.10.1
3. Navigate to Config > Box > Administrative Settings > DNS Settings.
4. Set the option in Run Forwarding/Caching DNS Config to No.
5. Restart the Proxy-Service.