Cisco Certified Network Associate (CCNA) Practice Exam

When configuring a trunk interface, which command sets the trunk encapsulation method?

1. (config)#switchport trunk encapsulation dot1q

2. (config)#switchport mode access

3. (config)#interface INTERFACE

4. (config)#switchport mode trunk

The correct answer is: (config)#switchport trunk encapsulation dot1q

The command that sets the trunk encapsulation method is indeed the one that specifies the encapsulation type, such as IEEE 802.1Q. By issuing the command for trunk encapsulation, you are defining how frames are tagged as they traverse a trunk link between switches. This is crucial because it ensures that the frames can be correctly recognized and handled by the receiving device. On the other hand, configuring the interface as "access" restricts it to a single VLAN and does not support trunking, which is not suitable for trunk interfaces. The command that specifies the interface context is important for accessing the configuration mode of the specific interface but does not set the encapsulation method. The command that sets the switch to trunk mode allows the interface to carry multiple VLANs, but it doesn't define how those VLANs are encapsulated. Understanding the specific role of these commands is essential for properly configuring trunk links in a network environment.