Cisco Certified Network Associate (CCNA) Practice Exam

Which command initiates the configuration of OSPF for IPv4?

1. (config)#interface ospf

2. (config-router)#router ospf

3. (config)#router ospf PROCESS NUMBER

4. (config-Router)#ip ospf start

The correct answer is: (config)#router ospf PROCESS NUMBER

The command that initiates the configuration of OSPF for IPv4 is crafted to establish an OSPF routing process on a Cisco router. When using the command that includes "router ospf" followed by a process number, you begin the process of configuring OSPF on the device. This process number is a locally significant identifier that allows the router to manage multiple OSPF processes independently if necessary. Entering the command within the global configuration mode puts the device into OSPF router configuration mode, where further OSPF settings, area configurations, network statements, and other related settings can be made. This is the fundamental step that enables OSPF functionality and is crucial for the establishment of OSPF routing in your network architecture. In contrast, other commands listed do not effectively initiate the OSPF configuration process. For example, the command to configure OSPF at the interface level or incorrectly structured command variants would not accomplish the intended goal of starting OSPF for IPv4. Therefore, the command chosen correctly identifies the necessary step to start configuring OSPF.