Cisco Certified Network Associate (CCNA) Practice Exam

If IP routing is enabled, which command sets the gateway of last resort?

1. ip route 0.0.0.0 0.0.0.0 172.16.2.1

2. ip default-network 0.0.0.0

3. Both ip route 0.0.0.0 0.0.0.0 172.16.2.1 and ip default-network 0.0.0.0

4. ip route 172.16.2.1 0.0.0.0

The correct answer is: Both ip route 0.0.0.0 0.0.0.0 172.16.2.1 and ip default-network 0.0.0.0

The command that sets the gateway of last resort is vital in routing because it determines where IP packets will be sent if there are no specific routes in the routing table for a given destination. Among the options provided, the command for establishing the gateway of last resort involves configurations that define how the router should handle unknown destinations. The command "ip route 0.0.0.0 0.0.0.0 172.16.2.1" explicitly defines a default static route. This command tells the router that if it doesn't have a specific route for a destination, it should forward the packets to the specified IP address, which forms the gateway of last resort, often used to point towards an exit router leading to the Internet or another network. On the other hand, the command "ip default-network 0.0.0.0" also plays a role in establishing a default routing behavior. Although it isn't as commonly used in modern networking scenarios, its purpose is to set a default network that will be used by the router to send packets that do not match any other specific routes. However, it aligns with the legacy methods of defining default behavior. Using both commands effectively sets the router to handle default routing conditions, thus ensuring that