Cisco Certified Network Associate (CCNA) Practice Exam

What is the purpose of the passive-interface command in OSPF?

1. To disable OSPF on the specified interface

2. To prevent OSPF hello packets from being sent on that interface

3. To automatically configure OSPF routers

4. To enable OSPF authentication on that interface

The correct answer is: To prevent OSPF hello packets from being sent on that interface

The passive-interface command in OSPF serves the specific purpose of preventing OSPF hello packets from being sent on a designated interface. By applying this command, OSPF maintains the route information and allows for the routing protocol to still receive updates from other interfaces, while keeping the selected interface from participating in the OSPF neighbor discovery process. This is particularly useful in scenarios where an interface connects to a subnet with no OSPF routers (such as a point-to-point link to a host) or when you want to avoid unnecessary OSPF traffic on a particular interface. The command does not disable OSPF completely on the interface, as it still allows for OSPF to process routing information; it simply stops the transmission of hello packets that are crucial for OSPF’s neighbor establishment. While it doesn't automatically configure routers, nor does it involve enabling OSPF authentication, its primary function is centered around managing the transmission of OSPF packets effectively.