1.
Which of the following fully encapsulates the original Ethernet frame in a trunking header rather than inserting another header inside the original Ethernet header?
Correct Answer
B. ISL
Explanation
ISL (Inter-Switch Link) is the correct answer because it fully encapsulates the original Ethernet frame in a trunking header rather than inserting another header inside the original Ethernet header. ISL is a Cisco proprietary protocol used for VLAN trunking, allowing multiple VLANs to be carried over a single link between switches. It adds a 26-byte header to the original Ethernet frame, including VLAN information, and then encapsulates the entire frame in a new Ethernet frame. This allows the VLAN information to be preserved as the frame is forwarded between switches.
2.
Which of the following adds the trunking header for all VLANs except one?
Correct Answer
C. 802.1Q
Explanation
802.1Q is the correct answer because it is a protocol used for trunking in Ethernet networks. It adds a 4-byte header to the Ethernet frame, which includes information about the VLAN the frame belongs to. This allows multiple VLANs to be carried over a single trunk link. Unlike ISL, which adds a header for all VLANs, 802.1Q allows for the exclusion of specific VLANs, making it the appropriate choice for adding the trunking header for all VLANs except one.
3.
Which of the following VTP modes allow VLANs to be configured on a switch?
Correct Answer(s)
B. Server
C. Transparent
Explanation
The VTP modes that allow VLANs to be configured on a switch are Server and Transparent. In Server mode, the switch can create, modify, and delete VLANs, and these changes are propagated to other switches in the VTP domain. In Transparent mode, the switch can create, modify, and delete VLANs, but these changes are not propagated to other switches. The other VTP modes, Client and Dynamic, do not allow VLAN configuration on the switch.
4.
Imagine that you are told that switch 1 is configured with the 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?
Correct Answer(s)
A. Trunking turned on
C. Desirable
Explanation
The 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.)
5.
A switch has just arrived from Cisco. The switch has never been configured with any VLANs, VTP configuration, or any other configuration. 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?
Correct Answer
A. VLAN 22 is listed in the output of the show vlan brief command.
Explanation
The default VTP setting of VTP server mode means that the switch can configure VLANs, so the VLAN is configured. However, being in server mode, the configuration commands only show up in the show vlan brief command output, and are not listed as part of the running-config file.
6.
Which of the following commands list the operational state of interface Gigabit 0/1 in regard to VLAN trunking?
Correct Answer(s)
B. Show interfaces gi0/1 switchport
C. Show interfaces gi0/1 trunk
Explanation
The command "show interfaces gi0/1 switchport" lists the operational state of interface Gigabit 0/1 in regard to VLAN trunking. This command specifically displays the switchport configuration and status information for the specified interface. On the other hand, the command "show interfaces gi0/1 trunk" is not applicable in this context as it displays information about trunk interfaces and their associated VLANs.
7.
An engineer has just installed four new 2960 switches and connected the switches to each other using crossover cables. All the interfaces are in an “up and up” state. The engineer configures each switch with the VTP domain name Fred and leaves all four switches in VTP server mode. The engineer adds VLAN 33 at 9:00 a.m., and then within 30 seconds, issues a show vlan brief command on the other three switches, but does not find VLAN 33 on the other three switches. Which answer gives the most likely reason for the problem in this case?
Correct Answer
C. None of the links between the switches trunk because of the default 2960 trunking administrative mode of auto.
Explanation
VTP does not require a password, although if a password is used, the password must match. VTP sends VTP updates immediately after a VLAN database change. However, VTP only sends VTP messages over trunks, and 2960s default to using a trunking administrative mode of auto, which does not initiate the trunking negotiation process. So, none of the switches automatically form a trunk, and no VTP messages are sent.
8.
Switches SW1 and SW2 connect through an operational trunk. The engineer wants to use VTP to communicate VLAN configuration changes. The engineer configures a new VLAN on SW1, VLAN 44, but SW2 does not learn about the new VLAN. Which of the following configuration settings on SW1 and SW2 would not be a potential root cause why SW2 does not learn about VLAN 44?
Correct Answer(s)
C. VTP pruning enabled and disabled, respectively
D. VTP modes of server and client, respectively
Explanation
The domain name and password must be equal, and the switches must connect using a trunk before VTP will work. It is normal to have some switches as servers and some as clients. A mismatched pruning configuration setting does not prevent the synchronization of VLAN databases.
9.
Which of the following IEEE 802.1d port states are stable states used when STP has completed convergence?
Correct Answer(s)
A. Blocking
B. Forwarding
Explanation
Listening and Learning are transitory port states, used only when moving from the Blocking to the Forwarding State. Discarding is not an 802.1d STP port state.
10.
Which of the following are transitory IEEE 802.1d port states used only during the process of STP convergence?
Correct Answer(s)
C. Listening
D. Learning
Explanation
Listening and Learning are transitory port states, used only when moving from the Blocking to the Forwarding state. Discarding is not an 802.1d STP port state. Forwarding and Blocking are stable states.
11.
Which of the following bridge IDs would win election as root, assuming that the switches with these bridge IDs were in the same network?
Correct Answer
C. 200:0200.1111.1111
Explanation
The smallest numeric bridge ID wins the election.
12.
Which of the following facts determines how often a nonroot bridge or switch sends an 802.1d STP Hello BPDU message?
Correct Answer
B. The Hello timer as configured on the root switch.
Explanation
Nonroot switches forward Hellos received from the root; the root sends these Hellos based on the root’s configured Hello timer.
13.
What STP feature causes an interface to be placed in the Forwarding State as soon as the interface is physically active?
Correct Answer
D. PortFast
Explanation
PortFast is a feature in STP (Spanning Tree Protocol) that allows an interface to immediately transition to the Forwarding State as soon as it becomes physically active. This feature is used to bypass the usual STP listening and learning states, which can cause delays in network connectivity. By enabling PortFast, the interface can start forwarding traffic without waiting for the usual STP convergence process, making it ideal for interfaces connected to end devices such as computers or printers.
14.
Which answer lists the name of the IEEE standard that improves the original STP standard and lowers convergence time?
Correct Answer(s)
B. RSTP
D. 802.1w
Explanation
The IEEE 802.1w standard, called Rapid STP, provides much faster STP convergence.
15.
Which of the following RSTP port states have the same name as a similar port state in traditional STP?
Correct Answer(s)
B. Forwarding
D. Learning
Explanation
RSTP uses port states of Forwarding, Learning, and Discarding, with Forwarding and Learning States performing the same basic functions as the STP port states with the same name.
16.
On a 2960 switch, which of the following commands change the value of the bridge ID?
Correct Answer(s)
B. Spanning-tree vlan vlan-number root {primary | secondary}
C. Spanning-tree vlan vlan-number priority value
Explanation
The command "spanning-tree vlan vlan-number root {primary | secondary}" changes the value of the bridge ID by specifying whether the switch should be the primary or secondary root bridge for the specified VLAN. The command "spanning-tree vlan vlan-number priority value" also changes the value of the bridge ID by setting the priority value for the specified VLAN.
17.
Examine the following extract from the show spanning-tree command on a Cisco switch:Which of the following answers is true regarding the switch on which this command output was gathered?
Correct Answer
B. The information is about the STP instance for VLAN 3.
Explanation
Cisco switches use the extended system ID format for bridge IDs by default, in which the priority field is broken down into a base priority value (32,768 in this case)plus the VLAN ID. The priority of this switch allows it to be capable of being the root switch, but the command output does not supply enough information to know whether this switch is currently root.
18.
Switch SW3 is receiving only two Hello BPDUs, both from the same root switch, received on the two interfaces listed as follows:SW3 has no STP-related configuration commands. The Hello received on Fa0/13 lists cost 10, and the Hello received on Gi0/1 lists cost 20. Which of the following is true about STP on SW3?
Correct Answer
B. SW3 will choose Gi0/1 as its root port.
Explanation
The two interfaces default to a port cost of 19 (Fa0/13) and 4 (Gi0/1), making SW3’s cost to reach the root 10 + 19 = 29 out Fa0/13, and 20 + 4 = 24 over Gi0/1. SW3 therefore chooses Gi0/1 as its root port. SW3 could then advertise a cost of 24 (cost to reach the root) Hello out Fa0/13, but it would be inferior to the Hello already being
received on Fa0/13 (cost 10), so SW3 would not choose Fa0/13 as a designated port.