DNS resolution not working when DNS Server configured to 'Same as Interface IP

Products:

FortiGate v5.2 FortiGate v5.4 FortiGate v5.6

This article provides a solution to DNS resolution not working when DNS Server is configured to “Same as Interface IP”.

DNS resolution can be seen to fail

Solution:

Enable the DNS Database Feature.

Configure a DNS Server for the interface that DNS requests will be sent to.

Set the mode to “Forward to System DNS”.

DNS resolution can now be seen to be successful.