Which NAT-related items should you inspect when troubleshooting port forwarding?

• A. Routing table
• B. DNS settings
• C. DHCP server
• D. Firewall NAT rules and logs

Answer: (D)

Port forwarding relies on NAT translating an external port to an internal IP and port, controlled by firewall rules. The items to inspect are the firewall NAT rules themselves and the logs, because they show exactly what port mappings exist, which internal host and port they point to, and whether traffic is being allowed, dropped, or misrouted. The logs can reveal misconfigurations like the wrong internal address, mismatched ports, or a rule that isn’t active, all of which explain why port forwarding isn’t working as expected.

Routing information affects how packets reach the NAT device but doesn’t establish or verify the actual port-forward mapping. DNS settings influence name resolution rather than how ports are forwarded. DHCP server settings affect IP addresses assigned to internal hosts, which can impact NAT if addresses change, but they don’t define the forward mappings themselves.