As a fundamental protocol for the internet, the DNS protocol must be working smoothly in our OPNsense system to avoid network issues. When users complain about internet connectivity issues, inexperienced analysts probably start the troubleshooting process by looking at the user’s web browser or even on the web proxy or in the firewall ruleset. However, a simple DNS test can sometimes solve the problem and also save a lot of time.

In this section, I’ll focus on the Unbound service because it is the default DNS service, so it’ll be applicable for most cases, but some configurations can be applied to other DNS services.

A common issue related to DNS services is that hosts can’t resolve names.

Common issues related to hosts that can’t resolve DNS names include the following:

• While using a DHCP server on OPNsense: The IP address set on the DHCP server isn’t listening for DNS queries. Check the DNS service configuration...