CCNPv8 ENCOR ( Version 8.0) – L2 Redundancy Exam Answers

Last updated Apr 22, 2022

CCNPv8 ENCOR (Version 8.0) – L2 Redundancy Exam Answers

Chapters 1 – 5: L2 Redundancy Exam Answers

1. What is the goal of Layer 3 switching?

to process packets at Layer 2 switching speeds while utilizing the scalability of routing
to provide a better path to the Internet without using routing protocols
to integrate all of the networking functions into one device
to implement the routing process by using routed protocols

Hint/Explanation: Switches that perform Layer 3 switching process packets at Layer 2 hardware speeds while providing the scalability of routing.

2. Which two statements are true about routed ports on a multilayer switch? (Choose two.)

To create a routed port requires removal of Layer 2 port functionality with the no switchport interface configuration command.
The interface vlan global configuration command is used to create a routed port.
A routed port is not associated with a particular VLAN.
A routed port behaves like a regular router interface and supports VLAN subinterfaces.
A routed port is a physical switch port with Layer 2 capability.

Hint/Explanation: A switch routed port is a Layer 3 port that requires removal of Layer 2 port functionality with the no switchport interface configuration command. VLANs are associated with switch Layer 2 access and trunk ports.

3. Which two statements are true about the 802.1Q trunking protocol? (Choose two.)

The native VLAN interface configurations must match at both ends of the link or frames could be dropped.
Untagged frames will be placed in the configured native VLAN of a port.
It is a proprietary protocol that is supported on Cisco switches only.
Private VLAN configurations are not supported.

Hint/Explanation: 802.1Q is a standard trunking protocol where untagged frames are placed on the native VLAN. The native VLAN must be configured the same at both ends of the trunk link.

4. Which technology does CEF switching use on Cisco hardware-based routers to forward packets?

forwarding engines implemented in specialized ASICs
interVLAN routing using subinterfaces
router general-purpose CPU
route processors using stateful switchover

Hint/Explanation: CEF switching on Cisco hardware-based routers uses forwarding engines implemented in specialized ASICs to forward packets. Cisco software-based routers use the general-purpose CPU for packet switching. InterVLAN routing using subinterfaces is not a CEF technology, and route processors using stateful switchover is a redundancy technology used by routers.

5. What type of specialized memory is used to facilitate high performance switching in Cisco multilayer switches?

address resolution protocol (ARP) memory
content-addressable memory (CAM)
ternary content addressable memory (TCAM)
Cisco Express Forwarding (CEF) memory

Hint/Explanation: CAM is used by ARP to store MAC and IPv4 address pairs. CEF uses a FIB.

6. Which protocol is required for Cisco Express Forwarding to be able to successfully forward packets on a multilayer switch?

VLAN Trunking Protocol
Cisco Discovery Protocol
Dynamic Trunking Protocol
Spanning Tree Protocol
Address Resolution Protocol

Hint/Explanation: In order to forward packets, Cisco Express Forwarding (CEF) requires the MAC address of the next hop provided by ARP.

7. If left to default configuration settings, what will determine which switch becomes the spanning-tree root bridge in a Layer 2 domain?

the lowest switch MAC address
the highest bridge ID
the highest bridge priority
the highest management IP address

Hint/Explanation: By default, all switches will have the same priority value, so the election of the root bridge will be based on the lowest MAC address.

8. During the implementation of Spanning Tree Protocol, all switches are rebooted by the network administrator. What is the first step of the spanning-tree election process?

All the switches send out BPDUs advertising themselves as the root bridge.
Each switch with a lower root ID than its neighbor will not send BPDUs.
Each switch determines the best path to forward traffic.
Each switch determines what port to block to prevent a loop from occurring.

Hint/Explanation: After a Cisco switch boots, it will send out BPDUs containing its individual BID and the root ID for the network. By default, the initial root ID at bootup will be the ID of that individual switch. After a root bridge is elected, port states and paths are chosen.

9. After the election of the root bridge has been completed, how will switches find the best paths to the root bridge?

Each switch will analyze the port states of all neighbors and use the designated ports to forward traffic to the root.
Each switch will analyze the sum of the hops to reach the root and use the path with the fewest hops.
Each switch will analyze the sum of all port costs to reach the root and use the path with the lowest cost.
Each switch will analyze the BID of all neighbors to reach the root and use the path through the lowest BID neighbors.

Hint/Explanation: After the election of a root bridge has occurred, each switch will have to determine the best path to the root bridge from its location. The path is determined by summing the individual port costs along the path from each switch port to the root bridge.

10. Which statement is true about the port roles of the 802.1w Rapid Spanning Tree Protocol?

An alternate or backup port can immediately change to a forwarding state without waiting for the network to converge.
Cisco-proprietary enhancements to the legacy 802.1D, such as UplinkFast and BackboneFast, are compatible with RSTP.
Ports are manually configured to be in the designated role.
It takes an edge port 15 seconds to go from blocking to forwarding.

Hint/Explanation: In order to create a loop-free topology, 802.1w RSTP has the following port roles: root, designated, alternate, edge, and backup. RSTP is able to actively confirm that a port can safely transition to the forwarding state without having to rely on a timer configuration.

11. Which three components are combined to form a bridge ID?

cost
MAC address
extended system ID
IP address
bridge priority
port ID

Hint/Explanation: The three components that are combined to form a bridge ID are bridge priority, extended system ID, and MAC address.

12. In which two port states does a switch learn MAC addresses and process BPDUs in a PVST network? (Choose two.)

forwarding
listening
blocking
learning
disabled

Hint/Explanation: Switches learn MAC addresses at the learning and forwarding port states. They receive and process BPDUs at the blocking, listening, learning, and forwarding port states.

13. Which STP priority configuration would ensure that a switch would always be the root switch?

spanning-tree vlan 10 priority 61440
spanning-tree vlan 10 root primary
spanning-tree vlan 10 priority 0
spanning-tree vlan 10 priority 4096

Hint/Explanation: Although the spanning-tree vlan 10 root primary command will ensure a switch will have a bridge priority value lower than other bridges introduced to the network, the spanning-tree vlan 10 priority 0 command ensures the bridge priority takes precedence over all other priorities.

14. Why is it important that the network administrator consider the spanning-tree network diameter when choosing the root bridge?

The cabling distance between the switches is 100 meters.
BPDUs may be discarded because of expiring timers.
The network diameter limitation is 9.
Convergence is slower as the BPDU travels away from the root.

Hint/Explanation: The optional diameter keyword in the spanning-tree vlan vlan-id root {primary | secondary} [diameter diameter] command allows for tuning of the STP convergence. The diameter keyword should reference the maximum number of Layer 2 hops that a switch can be from the root bridge and modify the timers accordingly. The timers do not need to be modified on other switches because they are carried throughout the topology through the root bridge BPDUs.

15. A network administrator enters the spanning-tree portfast bpduguard default command. What is the result of this command being issued on a Cisco switch?

Any switch port that has been configured with PortFast will be error-disabled if it receives a BPDU.
Any trunk ports will be allowed to connect to the network immediately, rather than waiting to converge.
Any switch port will be error-disabled if it receives a BPDU.
Any switch port that receives a BPDU will ignore the BPDU message.

Hint/Explanation: The spanning-tree bpduguard default command will enable BPDU guard on all switch ports that have PortFast-enabled. This will put the port in an error-disabled state if a BPDU from another switch is received on a PortFast-enabled interface.

16. In what situation would a network administrator most likely implement root guard?

on all switch ports that connect to a Layer 3 device
on all switch ports that connect to another switch that is not the root bridge
on all switch ports that connect to host devices
on all switch ports that connect to another switch
on all switch ports (used or unused)

Hint/Explanation: Root guard in conjunction with PortFast, and BPDU guard is used to prevent an STP manipulation attack.

17. Which technology is used to protect the switched infrastructure from problems caused by receiving BPDUs on ports that should not be receiving them?

Loop guard
PortFast
BPDU guard
RSPAN
Root guard

Hint/Explanation: To form a single path through a Layer 2 network, Layer 2 devices communicate with one another by the use of bridge protocol data units (BPDUs) as part of the Spanning Tree Protocol (STP). An attacker manipulates STP by spoofing the root bridge so that a device that is controlled by the attacker becomes a root bridge. The attacker can then obtain more information about the network or networks. BPDU guard can be used on ports that connect to user devices that are configured with PortFast so that BPDUs will not be accepted through that port.

18. What are the two options that describe the effects of the spanning-tree portfast command? (Choose two.)

Enabling PortFast on trunks that connect to other switches improves convergence.
If a switch port is configured with PortFast, it is an access port that immediately transitions from a blocking to forwarding state.
If the switch port is configured with PortFast, it waits 15 seconds before transitioning from a blocking to forwarding state.
Portfast bypasses the learning state and moves immediately into blocking.
Portfast enables the port to bypass the listening and learning states of STP.

Hint/Explanation: The portfast feature is enabled on a specific access port with the spanning-tree portfast command. One of the benefits of the STP portfast feature, is that the access ports bypass the earlier 802.1D STP states (learning and listening) and forward traffic immediately.

19. Which statement describes the term blocking in the operation of STP?

It indicates that the port has transitioned from a blocking state and can send or receive BPDUs, but cannot forward any other network traffic.
It indicates that the port is in an administratively off position.
It is a port state that is enabled but does not forward any traffic to ensure that a loop does not occur.
It is a port state that work traffic that it receives, but only forwards BPDUs and not any other network traffic.

20. What are two configuration parameters that must match for all switches in the same MST region? (Choose two.)

region name
trunk link encapsulation method
port status
version number
bridge priority

Hint/Explanation: The mst version number and region name must match for all switches in the same MST region. These parameters can be adjusted through MST configuration.

21. Assuming that all switches in a network have the default bridge priority for each MST instance, what effect does the command spanning-tree mst 10 root seconday have when entered on a single switch?

sets the bridge priority on the switch to 28672 for MST instance 10
sets the bridge priority on the switch to 24586 for MST instance 10
sets the bridge priority on the switch to 24576 for MST instance 10
sets the bridge priority on the switch to 24582 for MST instance 10

Hint/Explanation: In MST configuration, an MST instance priority can be defined in one of two methods:
spanning-tree mst instance-number priority priority , where the priority is a value between 0 and 61,440, in increments of 4096
spanning-tree mst instance-number root { primary | secondary }[ diameter diameter ], where the primary keyword sets the priority to 24,576, and the secondary keyword sets the priority to 28,672

22. Which two statements describe the MST internal spanning tree instance? (Choose two)

It is always instance 0.
It carries all VLANs traffic.
It runs on all switch port interfaces of switches that are designated as root bridges.
It runs on all switch port interfaces of switches in the MST region.
It carries identical setup information among interconnected MST regions.

Hint/Explanation: MST uses a special STP instance called the internal spanning tree (IST), which is always the first instance, instance 0. The IST runs on all switch port interfaces for switches in the MST region, regardless of the VLANs associated with the ports.

23. Refer to the exhibit. A network administrator is configuring MST tuning on SW1. The objective is to change the path cost value of the interface Gi1/0/1 to represent a higher-speed bandwidth link. Which value could be used in the command spanning-tree mst 0 cost for this task?

CCNPv8 ENCOR (Version 8.0) - L2 Redundancy Exam Q35 — CCNPv8 ENCOR (Version 8.0) – L2 Redundancy Exam Q35

0
1
24576
32768

Hint/Explanation: As shown in the output, the interface STP cost is derived from the media speed of the interface using the long-mode method. Using this method, the range of the interface path cost is from 1 to 200000000. A lower path cost represents higher-speed transmission bandwidth.

24. What are two misconfigurations within an MST region that might introduce port blocking unintentionally? (Choose two.)

misconfigured region name across the MST region
trunk link pruning
too many VLANs assigned to an instance
VLAN assignment to the IST
misconfigured revision number across the MST region

Hint/Explanation: VLAN assignment to the IST and trunk link pruning are two common misconfigurations within the MST region. A misconfigured region name or misconfigured revision number will cause the failure in forming the MST region.

25. How does an MST region send VLAN information through the PVST simulation mechanism to a switch that runs PVST+?

It sends out one PVST+ BPDU that maps all VLANs into VLAN1.
It sends out multiple PVST+ BPDUs, one for each VLAN, plus the IST.
It sends out PVST+ BPDUs, one for each VLAN, using the information from the IST.
It sends out one PVST+ BPDU with the information from the IST.

Hint/Explanation: The PVST simulation mechanism sends out PVST+ including RSTP BPDUs, one for each VLAN, using the information derived from the internal spanning tree (IST). This requires a mapping of one topology in IST to multiple VLANs toward the PVST link.

26. The network administrator wants to configure a switch to pass VLAN update information to other switches in the domain but not update its own local VLAN database. Which two steps should the administrator perform to achieve this? (Choose two.)

Configure VTP version 1 on the switch.
Configure the switch with the same VTP domain name as other switches in the network.
Verify that the switch has a higher configuration revision number.
Configure the VTP mode of the switch to transparent.
Reset the VTP counters.

Hint/Explanation: Besides the VTP domain name and mode needing to be configured, the switch must connect to other switches in the same VTP domain through a trunk in order to transmit/receive VTP information.

27. Which Cisco proprietary protocol is used for dynamically forming a trunk connection between two switches?

VTP
PAgP
STP
DTP

Hint/Explanation: Dynamic Trunking Protocol (DTP) is a Cisco proprietary protocol used for dynamically negotiating a trunk connection between two Cisco switches.

28. Which LACP technology can identify and remove a LACP enabled link from an EtherChannel within three seconds when the link is experiencing connectivity issues?

LACP min-links
LACP port priority
LACP system priority
LACP fast

Hint/Explanation: LACP fast advertises an LACP packet every second and after three seconds of not receiving an LACP packet, removes the link from the EtherChannel bundle.
LACP port priority allows an LACP enabled switch to select which member interfaces are active within a port-channel that has more member interfaces than the maximum allowed.
LACP system priority allows an LACP enabled switch to be designated as the master switch for a port-channel.
LACP min-links is used to configure a required minimum number of physical connections that must be active in order for the EtherChannel to stay active.

29. Which LACP technology is used for designating a specific number of member interfaces that must remain active in order for the EtherChannel bundle to be usable?

LACP port priority
LACP system priority
LACP min-links
LACP fast

30. Which LACP technology is used for designating which member interfaces will be active in a port-channel configuration where there are more member interfaces than the maximum allowed?

LACP system priority
LACP fast
LACP port priority
LACP min-links

Hint/Explanation: LACP fast advertises an LACP packet every second and after three seconds of not receiving an LACP packet, removes the link from the EtherChannel bundle.
LACP port priority allows an LACP enabled switch to select which member interfaces are active within a port-channel that has more member interfaces than the maximum allowed.
LACP system priority allows an LACP enabled switch to be designated as the master switch for a port-channel.
LACP min-links feature is used to configure a required minimum number of physical connections that must be active in order for the EtherChannel to stay active.

31. Refer to the exhibit. The administrator tried to create an EtherChannel between S1 and the other two switches via the commands that are shown, but was unsuccessful. What is the problem?

CCNPv8 ENCOR (Version 8.0) - L2 Redundancy Exam Q48 — CCNPv8 ENCOR (Version 8.0) – L2 Redundancy Exam Q48

Traffic can only be sent to two different switches if EtherChannel is implemented on Layer 3 switches.
Traffic cannot be sent to two different switches through the same EtherChannel link.
Traffic cannot be sent to two different switches, but only to two different devices like an EtherChannel-enabled server and a switch.
Traffic can only be sent to two different switches if EtherChannel is implemented on Gigabit Ethernet interfaces.

Hint/Explanation: An EtherChannel link can only be created between two switches or between an EtherChannel-enabled server and a switch. Traffic cannot be sent to two different switches through the same EtherChannel link.