Fortinet DNS Servers

[yeowkm99]

is it really useful to add fortinet DNS servers in the fortigate firewall DNS settings or we can use any public DNS servers ?

what are the benefits of adding fortinet DNS servers, 208.91.112.53 inside the fortigate firewall ?

[sjoshi · Accepted solution]

Dear yeowkm99,

Thank you for posting to the Fortinet Community Forum.

Problem Description:-
Query regarding Fortinet DNS server

The DNS server you have configured in FGT DNS settings will be used for fortiguard services and it is important.
Even though you use public dns still the fortiguard services will work but it is recommended to use fortiguard dns

If you add 208.91.112.53 then all your query related to the fortiguard services will be reach out to the fortiguard server and fortiguard dns server will be respinsible to solve those queries

Please find the article for the same
https://docs.fortinet.com/document/fortigate/6.2.0/cookbook/121810/using-a-fortigate-as-a-dns-server....

Let us know if this helps.

Thanks

[yeowkm99]

the reason for asking this is because recently, i have one remote office which encountered Internet outage.

We cannot even see the firewall WAN IP on the dashboard. 

After some troubleshooting, we discovered that we have 2 fortinet DNS servers configured on the firewall.  After replacing one of the DNS server with google DNS, the Internet works immediately.