Cisco Certified Network Associate (CCNA) Practice Exam

Which command propagates a default route in OSPF?

1. (config-router)#default-information originate never

2. (config-router)#default-information originate always

3. (config-router)#redistribute static

4. (config-router)#propagate default-route

The correct answer is: (config-router)#default-information originate always

The correct command for propagating a default route in OSPF is to use the "default-information originate" command with the "always" argument. This command tells the OSPF process to advertise a default route to other OSPF routers in the network, regardless of whether the router has a default route configured or not. When the "always" keyword is added, the command will force OSPF to always send out a default route, making sure that all neighboring routers are aware of it. This is particularly useful in networks where you want to ensure all devices can reach an outside network, such as the internet, and facilitates the routing of all traffic that doesn't match any other known routes. In contrast, using "never" in the first command would prevent the propagation of a default route, even if one exists, making it unsuitable for the task at hand. The third option, "redistribute static," would only send static routes, and while it could include a default route if it exists in the routing table, it does not guarantee that a default route will be included. The last option, "propagate default-route," is not a valid command in the context of OSPF, which makes it invalid as well.