To resolve all DNS requests on your router regardless of client configuration, what action should be set for the DST-NAT rule?

To ensure that all DNS requests are resolved on the router regardless of client configuration, the action that should be set for the DST-NAT rule is to redirect. When using the redirect action, the DNS requests made by clients are automatically sent to a specific DNS server, which in many cases would be the router itself. This means that any DNS queries sent to the standard port for DNS (UDP port 53) will be intercepted and redirected to the router's DNS service.

This is particularly useful in networks where clients are configured with DNS servers that may not be functioning, or where you want to ensure all DNS queries are handled reliably by the router to improve performance or control. By using the redirect option, you guarantee that the DNS traffic does not just pass through unmodified to potentially unreliable external DNS servers, but rather gets resolved locally by the router.

In contrast, the other options would not achieve this functionality. For example, masquerade is typically used for source NAT where the source address is changed, making it suitable for internet access but not for directing DNS traffic. Dst-nat also changes the destination but does not inherently redirect DNS requests to a predefined service. Not applicable doesn’t contribute to directing the DNS traffic at all, which is the main goal