Your PBXtra contains a GUI option to enable DNS forwarding if your company uses a DNS server (such as a Microsoft Exchange Server).
Your IP Phones must use the PBXtra as their primary DNS (see Why must I use the server as my Primary DNS?), but any computer attached to the LAN port on the back of the phones can have all DNS requests forwarded from the PBXtra to your actual DNS server.
Enable the DNS Forwarder
Login to your Admin Panel
Click on Options --> network
Under the DNS Settings section, insert the IP address of your Primary DNS server next to the DNS Forwarder field.
Click Apply All Changes
What did I accomplish?
By enabling the DNS Forwarder option, you LAN will operate as follows:
IP Phones will use your PBXtra as their Primary DNS server. The phones search for the IP of the server hostname ( sNNNN.pbxtra.fonality.com )
Any PC attached to the LAN port on the back of the phone will send DNS requests to your PBXtra . Your PBXtra will then immediately forward these requests to your actual company DNS server. Because both the PBXtra and your computers all exist on the same LAN, this forwarding operation is so fast that you will not notice any lag at all when browsing external domains (the web, an external FTP server, an off-site data center via VPN, etc.)