Cisco Certified Network Associate (CCNA) Practice Exam

What command would you enter to configure a subinterface of VLAN 10?

1. (config-subif)#ip address IP ADDRESS AND SUBNET MASK

2. (config-if)#interface INTERFACE.VLAN 10

3. (config-if)#encapsulation dot1q 10

4. (config-subif)#encapsulation 802.1Q 10

The correct answer is: (config-if)#encapsulation dot1q 10

To configure a subinterface for VLAN 10 specifically, the crucial and correct command would define the encapsulation method being used for that subinterface. The command to encapsulate the subinterface with the correct VLAN ID is essential for ensuring that the interface can handle packets tagged with that VLAN. Using the command to encapsulate 802.1Q with VLAN 10 indicates that the subinterface will be responsible for processing traffic associated with that VLAN. This configuration is necessary for routers and multilayer switches that handle VLAN traffic on their interfaces, effectively allowing them to manage inter-VLAN routing. Understanding this setup is fundamental in creating a functional virtual LAN environment, enabling traffic separation and improved network performance. It's worth noting that without proper encapsulation, the traffic for VLAN 10 would not be correctly identified, disrupting network operations.