300-410 NAT and PAT Configuration Scenarios

Explanation: Option A is correct because static NAT is created with the global configuration command ip nat inside source static <inside-local> <inside-global>, which permanently maps one inside local address to one inside global address. Option B is correct because the router must know which interface is the internal side, and that is done by entering the interface configuration and issuing the ip nat inside command on the interface facing the internal network. Option C is wrong because ip nat outside must be applied to the external-facing interface, not the internal one. Option D is wrong because an access list is used for dynamic NAT or PAT with the pool/overload syntax, not for a static one-to-one mapping. Option E is wrong because there is no global ip nat service command required to activate NAT on Cisco IOS; NAT is enabled by the inside/outside interface designations and the translation statements themselves.

Explanation: The output shows three dynamic NAT translations, all using the same inside global address 192.0.2.10 with unique source ports (10000, 10001, 10002). This is the hallmark of Port Address Translation (PAT) or NAT overload, where multiple inside hosts (10.0.0.10, 10.0.0.11, 10.0.0.12) share a single public IP address by differentiating sessions via layer-4 port numbers. The 'overload' keyword in the dynamic mapping confirms PAT is active and working correctly.

Explanation: CoPP policies that are too restrictive can drop legitimate control plane traffic, causing routing protocol adjacencies to flap. In this scenario, the policer rate of 1 Mbps is insufficient for OSPF and BGP traffic, leading to intermittent OSPF drops. Increasing the policed rate and burst size allows normal routing updates to pass while still providing protection against excessive traffic.

Explanation: The configuration uses an ACL (access-list 1) to match traffic from the 192.168.1.0/24 subnet, and the 'ip nat inside source list 1 interface GigabitEthernet0/1 overload' command translates all matching source IP addresses to the single IP address 203.0.113.1 (the outside interface IP) using Port Address Translation (PAT). This is a classic dynamic NAT overload configuration, where multiple internal hosts share one public IP by multiplexing on source ports.

Explanation: The configuration uses a static NAT with TCP port translation (also known as NAT with port forwarding). The command `ip nat inside source static tcp 10.0.0.10 80 198.51.100.10 8080 extendable` creates a one-to-one mapping between the inside local address/port (10.0.0.10:80) and the inside global address/port (198.51.100.10:8080). This means any incoming packet destined to 198.51.100.10 on TCP port 8080 will have its destination translated to 10.0.0.10 port 80, and the response traffic is reverse-translated. Option B correctly describes this behavior.