CCNP Mock Exam 106 — 25 Questions

Question 1

An engineer is troubleshooting a problem where a trunk link between two Cisco switches is not passing traffic for VLAN 10, but other VLANs are working. The trunk is configured with switchport mode trunk on both sides. The engineer checks the allowed VLAN list and sees VLAN 10 is included. The native VLAN is set to 1 on both sides. What is the most likely cause?

Accepted Answer

VLAN 10 is not created in the VLAN database on one of the switches.. The most likely cause is that VLAN 10 is not created in the VLAN database on one of the switches. Even if VLAN 10 is included in the allowed VLAN list on the trunk, a switch will not forward traffic for a VLAN that does not exist in its local VLAN database. The trunk interface will be operationally down for that specific VLAN, preventing traffic from passing.

Answer

VTP pruning has removed VLAN 10 from the trunk.

Answer

The native VLAN is mismatched.

Answer

Spanning Tree Protocol is blocking VLAN 10 on the trunk.

Question 2

A network engineer runs the following command on Switch SW1:

SW1# show etherchannel summary

Flags:  D - down        P - bundled in port-channel
        I - stand-alone s - suspended
        H - Hot-standby (LACP only)
        R - Layer3      S - Layer2
        U - in use      N - not in use, no aggregation
        f - failed to allocate aggregator

M - not in use, minimum links not met
        u - unsuitable for bundling
        w - waiting to be aggregated
        d - default port

Number of channel-groups in use: 1
Number of aggregators:           1

Group  Port-channel  Protocol    Ports
------+-------------+-----------+--------------------------------------------
1      Po1(SU)         LACP      Gi0/1(P)   Gi0/2(P)   Gi0/3(D)

Based on this output, what can be concluded?

Accepted Answer

The EtherChannel has two active member links.. The output shows that Gi0/1 and Gi0/2 have a flag of 'P' (bundled in port-channel), while Gi0/3 has a flag of 'D' (down). Therefore, only two ports are actively bundled, making option D correct. The 'SU' flags on Po1 indicate the port-channel is Layer 2 (S) and in use (U), not Layer 3.

Answer

The EtherChannel is using PAgP.

Answer

Port Gi0/3 is bundled in the channel.

Answer

The port-channel is a Layer 3 interface.

Question 3

A network engineer runs the following command on Switch SW1:

SW1# show vlan brief

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Gi0/1, Gi0/2, Gi0/3
10   Sales                            active    Gi0/4, Gi0/5
20   Engineering                      active    Gi0/6, Gi0/7
1002 fddi-default                     act/unsup
1003 token-ring-default               act/unsup
1004 fddinet-default                  act/unsup
1005 trnet-default                    act/unsup

Based on this output, what can be concluded?

Accepted Answer

Interfaces Gi0/1, Gi0/2, and Gi0/3 are in VLAN 1.. Option C is correct because the 'show vlan brief' output explicitly lists Gi0/1, Gi0/2, and Gi0/3 under VLAN 1 (default), confirming these interfaces are access ports assigned to VLAN 1. VLAN 1 is the default VLAN on Cisco switches, and all ports not explicitly configured otherwise belong to it.

Answer

All ports shown are in trunk mode.

Answer

VLANs 1002-1005 are active and supported.

Answer

VLAN 20 has no ports assigned.

Question 4

A network engineer runs the following command on Switch SW1:

SW1# show interfaces gi0/1 trunk

Port        Mode         Encapsulation  Status        Native vlan
Gi0/1      desirable    n-802.1q       trunking      1

Port        Vlans allowed on trunk
Gi0/1       1-1005

Port        Vlans allowed and active in management domain
Gi0/1       1,10,20

Port        Vlans in spanning tree forwarding state and not pruned
Gi0/1       1,10,20

Based on this output, what can be concluded?

Accepted Answer

VLANs 2-9 are allowed but not active.. The output shows that VLANs 1-1005 are allowed on the trunk, but only VLANs 1, 10, and 20 are active in the management domain. This means VLANs 2-9 and 11-19, 21-1005 are allowed but not active (i.e., not created or not present on the switch). Option C correctly identifies that VLANs 2-9 are among those allowed but not active.

Answer

The interface is configured as an access port.

Answer

The trunk is using ISL encapsulation.

Answer

The native VLAN is 10.

Question 5

A network engineer runs the following command on Switch SW1:

SW1# show interfaces gi0/1 switchport

Name: Gi0/1
Switchport: Enabled
Administrative Mode: trunk
Operational Mode: trunk
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: dot1q
Negotiation of Trunking: On
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Administrative Native VLAN tagging: enabled
Voice VLAN: none
Administrative private-vlan host-association: none
Administrative private-vlan mapping: none
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk Native VLAN tagging: enabled
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk private VLANs: none
Operational private-vlan: none
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001
Capture Mode Disabled
Capture VLANs Allowed: ALL

Based on this output, what can be concluded?

Accepted Answer

DTP is enabled on this interface.. The output shows 'Negotiation of Trunking: On', which indicates that Dynamic Trunking Protocol (DTP) is enabled on the interface. DTP is a Cisco proprietary protocol used to negotiate trunking between switches. Since the interface is in trunk mode and DTP is on, option B is correct.

Answer

The interface is configured as an access port.

Answer

The native VLAN is tagged with 802.1Q.

Answer

All VLANs except 2-1001 are pruned.

Question 6

A network engineer is configuring a new Cisco Nexus 9000 switch to connect to an existing Cisco Catalyst 3850 switch. The link between them should be a trunk carrying VLANs 10, 20, and 30. The engineer configures the Nexus switch with 'switchport mode trunk' and 'switchport trunk allowed vlan 10,20,30'. However, the trunk does not come up. The Catalyst switch is configured with 'switchport mode trunk' and 'switchport trunk allowed vlan 10,20,30'. What is the most likely cause?

Accepted Answer

The Nexus switch does not have the 'switchport trunk encapsulation dot1q' command configured.. The most likely cause is that the Nexus switch defaults to 802.1Q encapsulation, but the Cisco Catalyst 3850 switch requires the explicit 'switchport trunk encapsulation dot1q' command to be configured on the Nexus side. Without this command, the Nexus switch may not properly negotiate or establish the trunk, as the Catalyst switch expects a specific encapsulation type. This is a common issue when interconnecting different Cisco switch platforms that handle trunk encapsulation defaults differently.

Answer

The Catalyst switch is set to dynamic auto mode.

Answer

The allowed VLAN list on the Nexus switch is missing VLAN 1.

Answer

The native VLAN is set to 999 on the Nexus switch.

Question 7

A network engineer runs the following command on Switch SW1:

SW1# show vlan id 10

VLAN ID: 10
VLAN Name: Sales
VLAN Type: Ethernet
VLAN State: active
MTU: 1500

Remote SPAN VLAN: No

Primary VLAN ID: 10

Private VLAN Type: Primary

Associated Secondary VLAN IDs: 100, 200

Based on this output, what can be concluded?

Accepted Answer

VLAN 10 is a primary private VLAN.. The output shows VLAN 10 configured as a Primary VLAN with associated secondary VLANs 100 and 200, which is the defining characteristic of a primary private VLAN. This is confirmed by the fields 'Private VLAN Type: Primary' and 'Associated Secondary VLAN IDs: 100, 200'. Therefore, VLAN 10 is a primary private VLAN, not a normal data VLAN.

Answer

VLAN 10 is a community VLAN.

Answer

VLAN 10 is an isolated VLAN.

Answer

VLAN 10 is a normal data VLAN with no private VLAN features.

Question 8

A network engineer runs the following command on Switch SW1:

SW1# show interfaces trunk

Port        Mode         Encapsulation  Status        Native vlan
Gi0/1      on           802.1q         trunking      1
Gi0/2      on           802.1q         trunking      1

Port        Vlans allowed on trunk
Gi0/1       1-1005
Gi0/2       1-1005

Port        Vlans allowed and active in management domain
Gi0/1       1,10,20
Gi0/2       1,10,20

Port        Vlans in spanning tree forwarding state and not pruned
Gi0/1       1,10,20
Gi0/2       1,10,20

Based on this output, what can be concluded?

Accepted Answer

VLANs 2-9 are allowed but not active on the trunk.. The output shows that VLANs 1-1005 are allowed on the trunk, but only VLANs 1, 10, and 20 are listed as active in the management domain. This means VLANs 2-9 are configured on the trunk but are not active (i.e., not created or not present on the switch), so they do not forward traffic. Option A correctly identifies this condition.

Answer

The trunk is using ISL encapsulation.

Answer

VLAN 1 is pruned from the trunk.

Answer

Only VLANs 10 and 20 are forwarding traffic.

Question 9

Examine the following configuration snippet on a Cisco IOS switch:

interface GigabitEthernet0/2
 switchport mode access
 switchport access vlan 50
 spanning-tree portfast

Which statement is true about this interface?

Accepted Answer

The interface will immediately forward traffic without any spanning-tree delay.. The `spanning-tree portfast` command on an access port configured with `switchport mode access` and `switchport access vlan 50` causes the interface to bypass the normal spanning-tree listening and learning states. This allows the port to transition directly to the forwarding state, enabling immediate traffic forwarding without the usual 30-second delay (15 seconds for listening, 15 seconds for learning) associated with Rapid Spanning Tree Protocol (RSTP) or the 50-second delay with classic STP (802.1D).

Answer

The interface will participate in trunking and forward multiple VLANs.

Answer

The interface will still go through listening and learning states before forwarding.

Answer

The interface will only forward traffic for VLAN 1.

Question 10

What is the default native VLAN on a Cisco switch trunk port?

Accepted Answer

VLAN 1. The default native VLAN on a Cisco switch trunk port is VLAN 1. The native VLAN is the VLAN that carries untagged traffic over a trunk link, and by default, all switch ports (including trunk ports) belong to VLAN 1. This is defined in the IEEE 802.1Q standard, which specifies that frames on the native VLAN are not tagged with a VLAN ID.

Answer

VLAN 0

Answer

VLAN 1002

Answer

VLAN 4095

Question 11

Given the following configuration on a Cisco IOS switch:

interface GigabitEthernet0/6
 switchport mode dynamic desirable

What is the effect of this configuration?

Accepted Answer

The interface will actively try to form a trunk and will succeed if the other side is set to trunk, desirable, or auto.. The `switchport mode dynamic desirable` command configures the interface to actively send Dynamic Trunking Protocol (DTP) frames to negotiate trunking. If the neighboring interface is set to trunk, dynamic desirable, or dynamic auto, the negotiation will succeed and the link will become a trunk. This is because dynamic desirable actively initiates the negotiation, unlike dynamic auto which only responds.

Answer

The interface will only become a trunk if the other side is set to trunk.

Answer

The interface will always remain an access port.

Answer

The interface will not send DTP frames.

Question 12

A network engineer runs the following command on Switch SW1:

SW1# show interfaces gi0/1 trunk

Port        Mode         Encapsulation  Status        Native vlan
Gi0/1      on           802.1q         trunking      1

Port        Vlans allowed on trunk
Gi0/1       10,20

Port        Vlans allowed and active in management domain
Gi0/1       10,20

Port        Vlans in spanning tree forwarding state and not pruned
Gi0/1       10,20

Based on this output, what can be concluded?

Accepted Answer

Only VLANs 10 and 20 are allowed on this trunk.. The output shows that the 'Vlans allowed on trunk' list contains only VLANs 10 and 20. This means the trunk has been explicitly configured to permit only those VLANs, and all other VLANs (including VLAN 1) are pruned or blocked from traversing the trunk. Therefore, only VLANs 10 and 20 are allowed, making option C correct.

Answer

VLAN 1 is allowed on this trunk.

Answer

The trunk is using DTP dynamic desirable mode.

Answer

The native VLAN is 10.

Question 13

What is the purpose of the Dynamic Trunking Protocol (DTP) on Cisco switches?

Accepted Answer

To automatically negotiate trunking between two Cisco switches.. DTP (Dynamic Trunking Protocol) is a Cisco proprietary protocol used to automatically negotiate the operational mode (access or trunk) of a switch port between two Cisco switches. When both ends are configured with DTP modes like dynamic desirable or dynamic auto, the link can become a trunk without manual configuration, simplifying deployment in environments where trunking is needed.

Answer

To dynamically assign VLANs to access ports.

Answer

To provide security by encrypting trunk traffic.

Answer

To prevent loops in the network.

Question 14

Examine the following configuration on a Cisco IOS-XE switch:

interface GigabitEthernet0/5
 switchport mode trunk
 switchport trunk native vlan 999
 switchport trunk allowed vlan 10,20,30
 switchport nonegotiate

What is the effect of the 'switchport nonegotiate' command?

Accepted Answer

The interface will not send or process DTP frames, and remains a trunk.. The 'switchport nonegotiate' command disables Dynamic Trunking Protocol (DTP) on the interface. When configured on a trunk port, the interface will neither send nor process any DTP frames, ensuring the port remains in trunk mode regardless of the neighbor's DTP configuration. This is commonly used when connecting to non-Cisco devices that do not support DTP, or to prevent unwanted trunk negotiation.

Answer

The interface will not send DTP frames, but will still respond to incoming DTP frames.

Answer

The interface will revert to an access port.

Answer

The interface will negotiate trunking using ISL instead of DTP.

Question 15

A network engineer runs the following command on Switch SW1:

SW1# show dtp interface gi0/1

DTP information on GigabitEthernet0/1:
  DTP:                      Enabled
  DTP mode:                 Desirable
  DTP negotiate:            TRUE
  DTP status:               Trunk
  DTP trunk status:         Trunking
  DTP timer:                30
  DTP max-age:              2
  DTP encapsulation:        802.1q
  DTP refresh rate:         Both
  DTP requests:             10
  DTP errors:               0

Based on this output, what can be concluded?

Accepted Answer

The interface will not form a trunk unless the neighbor is set to trunk or desirable.. The output shows DTP mode is 'Desirable' and DTP status is 'Trunking', meaning the interface is actively attempting to form a trunk. In DTP, a switchport in desirable mode will only successfully negotiate a trunk if the neighboring interface is configured as trunk (on) or desirable; if the neighbor is in access mode or dynamic auto, the trunk will not form. Therefore, option B is correct.

Answer

The interface is in access mode.

Answer

The interface is using ISL encapsulation.

Answer

DTP is disabled on this interface.

Question 16

Consider the following configuration on a Cisco IOS-XE switch:

interface GigabitEthernet0/3
 switchport trunk encapsulation dot1q
 switchport mode trunk
 switchport trunk native vlan 1

What is the effect of this configuration?

Accepted Answer

The interface will operate as an 802.1Q trunk, and untagged frames will be associated with VLAN 1.. The configuration sets the interface to 802.1Q trunking mode and explicitly defines VLAN 1 as the native VLAN. On an 802.1Q trunk, the native VLAN is the VLAN to which untagged frames are assigned when received on the trunk port. Since VLAN 1 is the default native VLAN and is explicitly configured here, untagged frames will be associated with VLAN 1, allowing them to traverse the trunk without an 802.1Q tag.

Answer

The interface will operate as an ISL trunk.

Answer

The interface will drop all untagged frames.

Answer

The interface will only forward traffic for VLAN 1.

Question 17

Given the following configuration on a Cisco IOS switch:

interface GigabitEthernet0/4
 switchport mode trunk
 switchport trunk allowed vlan except 100-200

What is the effect of this configuration?

Accepted Answer

The trunk will forward traffic for all VLANs except VLANs 100 through 200.. The 'switchport trunk allowed vlan except 100-200' command explicitly removes VLANs 100 through 200 from the allowed VLAN list on the trunk. All other VLANs (1-99 and 201-4094) remain permitted. This is the standard behavior of the 'except' keyword in Cisco IOS trunk configuration.

Answer

The trunk will only forward traffic for VLANs 100 through 200.

Answer

The trunk will forward traffic for all VLANs.

Answer

The trunk will not forward any traffic because the allowed list is empty.

Question 18

Which of the following is a valid VLAN range that can be created on a Cisco IOS switch?

Accepted Answer

VLAN 100. VLAN 100 is a valid VLAN ID because Cisco IOS switches support VLANs in the range 1–1005 for normal-range VLANs, and VLAN 100 falls within this range. Normal-range VLANs are stored in the vlan.dat file and can be created on a standard IOS switch without requiring extended VLAN configuration.

Answer

VLAN 0

Answer

VLAN 4095

Answer

VLAN 1006

Question 19

A network engineer is configuring a new switch that will be used as an access layer switch. The switch connects to two distribution switches via trunk links. The engineer wants to ensure that the access switch does not become the root bridge for any VLAN. The engineer also wants to provide redundancy so that if one uplink fails, the other uplink takes over quickly. The engineer is using Rapid PVST+. What configuration should the engineer apply on the access switch?

Accepted Answer

Configure 'spanning-tree vlan vlan-list priority 61440' on the access switch.. Option A is correct because setting the spanning-tree priority to 61440 (which is 0xF000 in hex) makes the switch a very unlikely root bridge candidate. In Rapid PVST+, the bridge priority is a 4-bit value (0-15) multiplied by 4096, so 61440 corresponds to priority 15 — the highest possible value. This ensures the access switch will never become the root bridge for any VLAN, while Rapid PVST+ provides fast failover (sub-second convergence) via its alternate/backup port mechanism without needing UplinkFast.

Answer

Configure 'spanning-tree vlan vlan-list priority 0' on the access switch.

Answer

Enable UplinkFast on the access switch to provide fast failover.

Answer

Enable PortFast on the trunk ports to speed up convergence.

Question 20

A network engineer is troubleshooting a Layer 2 loop issue. The network consists of three switches: SW1, SW2, and SW3, all connected in a triangle. The engineer notices that SW1 is the root bridge. After a link failure between SW1 and SW2, the network experiences a temporary loop. The engineer wants to prevent such loops in the future by enabling a feature that provides faster convergence and prevents temporary loops during topology changes. The engineer is using Rapid PVST+. Which feature should the engineer enable?

Accepted Answer

Enable Loop Guard on all switch ports.. When a link fails in a triangle topology with Rapid PVST+, the switch that lost its root port may temporarily transition a blocked alternate port to forwarding before the new root port is fully synchronized, causing a loop. Enabling Loop Guard on all switch ports prevents this by keeping a port in a blocking state if BPDUs are not received, ensuring that a port does not erroneously transition to forwarding during a topology change. This provides faster convergence without temporary loops by enforcing BPDU-based loop prevention.

Answer

Enable BPDU Guard on all switch ports.

Answer

Enable Root Guard on all switch ports.

Answer

Enable UDLD on all fiber links.