Cisco Certified Network Associate (CCNA) Practice Exam

What is the correct command to assign a subinterface to a VLAN with 802.1Q trunking?

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

2. (config-subif)#encapsulation dot1q VLAN NUMBER

3. (config)#encapsulation frame-relay

4. (config-if)#frame-relay map ip REMOTE IP ADDRESS

The correct answer is: (config-subif)#encapsulation dot1q VLAN NUMBER

The correct command to assign a subinterface to a VLAN with 802.1Q trunking is the command that sets the encapsulation type to 802.1Q and specifies the VLAN number. This command is essential for configuring subinterfaces on a router to handle traffic coming in and out of a specific VLAN on a trunk link. When using 802.1Q trunking, each subinterface represents a different VLAN, allowing for multiple VLANs to share the same physical interface. By issuing the encapsulation dot1q VLAN NUMBER command in the configuration mode of the subinterface, you define how the router should handle traffic tagged for that VLAN. It effectively informs the router that it will be handling VLAN-tagged traffic, and thus needs to recognize and process the frames correctly based on the VLAN ID. The other commands provided do not pertain to the configuration of subinterfaces with 802.1Q. For instance, commands related to Frame Relay configurations, such as the encapsulation frame-relay and the frame-relay map ip commands, are specific to a different type of network technology and are irrelevant to VLAN trunking. The command in the first choice merely addresses the assignment of an IP address and subnet mask to an interface, without any relation