Add Multiple DNS IP in Fortigate Fw

[Ranjith1]

Dear Team,

Currently, we are using the 1200D firewall in our corporate office.  In the Box, we have created multiple ADOMs and multiple ISP links as well. Hover, we are facing the issues in DNS lookup field error in the sum of the websites. And we have already configured Global VDOMs in global DNS like 8.8.8.8 and 4.2.2.2. 

But, when we are facing the issue of a DNS lookup failed error, we have to change the DNS IP as per the ISP providing the own DNS IPs. 

Could you tel me any option available in FortiGate to configure the multiple DNS IPs?  If the option it's available please

[IT_Ahan2]

what are the current DNS Ips ?

[Ranjith1]

Current DNS IP 8.8.8.8 and  4.2.2.2

[Mohamed_Gaber]

Does it work for the Global VDOM?

"we have to change the DNS IP as per the ISP providing the own DNS IPs"; It seems the ISP is blocking DNS requests to other DNS servers.

Could FortiGate itself resolve DNS and access FortiGuard?

[Ranjith1]

Ya, We tried Foriguard DNS also, It's getting more latency compared with google DNS.

Do you have any settings required for the DNS configuration in VDOM? 

[Mohamed_Gaber]

"It's getting more latency compared with google DNS"; The latency occurs with google DNS or ISP DNS?

[Ranjith1]

The latency occurs when we configure the Fortiguard DNS. Currently, ISP DNS is not configured. In Fortigate only 2 options are available Primary and secondary. Now we have configured the google DNS.  

[Mohamed_Gaber]

"The latency occurs when we configure the Fortiguard DNS"; It seems that FortiGate could not access FortiGuard.

Configure the ISP DNS and try to execute ping to a site from FortiGate CLI and nslookup from the client's CMD.

[Mohamed_Gaber]

config system dns
set primary <ISP DNS>
set secondary 8.8.8.8

end

[Ranjith1]

Hi, we have the 3 VDOM. in all VDOMs we have 3 ISP links. How to configure the per VDOM DNS?