Chapter 11 - Implementing Ethernet Virtual LANs Flashcards
In a LAN, which of the following terms best equates to the term VLAN?
a. Collision domain
b. Broadcast domain
c. Subnet
d. Single switch
e. Trunk
B.
A VLAN is a set of devices in the same Layer 2 broadcast domain. A subnet often includes the exact same set of devices, but it is a Layer 3 concept. A collision domain refers to a set of Ethernet devices, but with different rules than VLAN rules for determining which devices are in the same collision domain.
Imagine a switch with three configured VLANs. How many IP subnets are required, assuming that all hosts in all VLANs want to use TCP/IP?
a. 0
b. 1
c. 2
d. 3
e. You cannot tell from the information provided.
D.
Although a subnet and a VLAN are not equivalent concepts, the devices in one VLAN are typically in the same IP subnet and vice versa.
Switch SW1 sends a frame to switch SW2 using 802.1Q trunking. Which of the answers describes how SW1 changes or adds to the Ethernet frame before forwarding the frame to SW2?
a. Inserts a 4-byte header and does change the MAC addresses
b. Inserts a 4-byte header and does not change the MAC addresses
c. Encapsulates the original frame behind an entirely new Ethernet header
d. None of the other answers are correct
B.
802.1Q defines a 4-byte header, inserted after the original frame’s destination and source MAC address fields. The insertion of this header does not change the original frame’s source or destination address. The header itself holds a 12-bit VLAN ID field, which identifies the VLAN associated with the frame.
Imagine that you are told that switch 1 is configured with the dynamic auto parameter for trunking on its Fa0/5 interface, which is connected to switch 2. You have to configure switch 2. Which of the following settings for trunking could allow trunking to work?
(Choose two answers.)
a. on
b. dynamic auto
c. dynamic desirable
d. access
e. None of the other answers are correct.
A and C.
The dynamic auto setting means that the switch can negotiate trunking, but it can only respond to negotiation messages, and it cannot initiate the negotiation process. So, the other switch must be configured to trunk or to initiate the negotiation process (based on being configured with the dynamic desirable option).
A switch has just arrived from Cisco. The switch has never been configured with any VLANs, but VTP has been disabled. An engineer gets into configuration mode and issues the vlan 22 command, followed by the name Hannahs-VLAN command. Which of the following are true?
(Choose two answers.)
a. VLAN 22 is listed in the output of the show vlan brief command.
b. VLAN 22 is listed in the output of the show running-config command.
c. VLAN 22 is not created by this process.
d. VLAN 22 does not exist in that switch until at least one interface is assigned to that VLAN.
A and B.
The configured VTP setting of VTP transparent mode means that the switch can configure VLANs, so the VLAN is configured. In addition, the VLAN configuration details, including the VLAN name, show up as part of the running-config file.
Which of the following commands identify switch interfaces as being trunking interfaces: interfaces that currently operate as VLAN trunks?
(Choose two answers.)
a. show interfaces
b. show interfaces switchport
c. show interfaces trunk
d. show trunks
B and C.
The show interfaces switchport command lists both the administrative and operational status of each port. When a switch considers a port to be trunking, this command lists an operational trunking state of “trunk.” The show interfaces trunk command lists a set of interfaces: the interfaces that are currently operating as trunks. So, both of these commands identify interfaces that are operational trunks.
