Cisco Certified Network Associate (CCNA) Practice Exam

What does the command 'no shut' do on a router interface?

1. Disables the interface

2. Enables the interface

3. Sets the interface to a shutdown state

4. Configures the interface IP address

The correct answer is: Enables the interface

The command 'no shut' is used on a router interface to enable that interface. By default, many router interfaces are in a shutdown state when first configured, meaning they are administratively disabled and cannot send or receive traffic. When the command 'no shut' is applied, it effectively transitions the interface from a shutdown state to an active state, allowing it to operate and participate in the routing functions of the network. This command is essential during configuration because it ensures that the interface can begin processing data packets, including those involved in routing protocols and communication with directly connected devices. When an interface is enabled, it can go through the initialization process, obtain or assign an IP address (if additional configurations are applied), and be included in the routing table, thereby facilitating communication across the network.