CCNA Practice Exam Test Sample – Question 32

In a switched environment, what does the IEEE 802.1Q standard describe?

A. the operation of VTP
B. a method of VLAN trunking
C. an approach to wireless LAN communication
D. the process for root bridge selection
E. VLAN pruning

Correct Answer: B
Section: LAN Switching Technologies

Explanation:
A broadcast domain must sometimes exist on more than one switch in the network. To accomplish this, one switch must send frames to another switch and indicate which
VLAN a particular frame belongs to. On Cisco switches, a trunk link is created to accomplish this VLAN identification. ISL and IEEE 802.1Q are different methods of putting a VLAN identifier in a Layer 2 frame.
The IEEE 802.1Q protocol interconnects VLANs between multiple switches, routers, and servers. With 802.1Q, a network administrator can define a VLAN topology to span multiple physical devices.
Cisco switches support IEEE 802.1Q for FastEthernet and Gigabit Ethernet interfaces. An 802.1Q trunk link provides VLAN identification by adding a 4-byte tag to an Ethernet Frame as it leaves a trunk port.