CCNA Switching and Network Access Practice Test 21 — 15 Questions

Question 1

Drag and drop the following steps into the correct order to configure an LACP EtherChannel on two Cisco switches using active mode.

Accepted Answer

Enter interface configuration mode for the physical ports (interface range gigabitethernet 0/1-2).. To configure an LACP EtherChannel in active mode, you must first enter interface configuration mode on the physical interfaces (e.g., using interface range). Next, assign those interfaces to a channel group using the channel-group command with the mode active keyword; this enables LACP negotiation and ensures the switch actively attempts to form a bundle. After the member ports are configured, you can optionally set parameters on the Port-Channel interface (such as switchport mode trunk). Finally, verify the EtherChannel is operational with show etherchannel summary. Using mode passive, on, or desirable would not enable LACP active negotiation or would use a different protocol (PAgP), which does not meet the requirement.

Question 2

Which THREE statements correctly describe the behavior of LACP modes in an EtherChannel configuration?

Accepted Answer

Passive mode will only respond to LACP packets and will not initiate negotiation.. B is correct because passive mode interfaces only respond to LACP packets and never initiate negotiation. C is correct because two passive interfaces will both wait for the other to initiate, so no LACP packets are sent and the EtherChannel never forms. D is correct because active mode interfaces actively send LACP packets to initiate negotiation with either an active or passive peer. A is incorrect: active mode sends LACP packets regardless of the peer’s mode; it can form a channel with passive just as well as with active. E is incorrect because PAgP supports only desirable and auto modes, not LACP’s active/passive modes; PAgP and LACP are separate protocols.

Answer

Active mode will not send LACP packets unless the peer is also in active mode.

Answer

Both active and passive modes are supported in PAgP.

Question 3

You are connected to R1. Configure inter-VLAN routing on R1 using router-on-a-stick so that hosts in VLAN 10 (192.168.10.0/24) and VLAN 20 (192.168.20.0/24) can communicate. The switch SW1 is already configured with VLANs and trunking, but R1's current configuration prevents traffic. Identify and fix the issues.

Accepted Answer

Enable the physical interface with the 'no shutdown' command on R1.. The issue was that the physical interface GigabitEthernet0/0 on R1 was administratively down, causing all subinterfaces for VLANs 10 and 20 to be in a down state. Enabling it with 'no shutdown' brings the trunk up, allowing inter-VLAN routing because the switch already has trunking configured. The other options are incorrect because they suggest steps that are either already in place (IP routing) or not needed (changing encapsulation or moving no shutdown to subinterfaces).

Answer

Change the encapsulation on the subinterfaces to use dot1Q with native VLAN 10 and 20 respectively.

Answer

Enable IP routing globally with the 'ip routing' command on R1.

Answer

Remove the 'no shutdown' from the subinterfaces and apply it only to the physical interface.

Question 4

You are connected to R1. The network uses a router-on-a-stick design with a single switch (SW1) and two VLANs (10 and 20). Currently, hosts in VLAN 10 cannot ping hosts in VLAN 20, and the trunk between R1 and SW1 shows a native VLAN mismatch. Examine the provided configuration and output, then apply the necessary corrections to R1 so that inter-VLAN routing works correctly.

Accepted Answer

Change the native VLAN on R1's trunk interface to 99, correct the encapsulation on G0/0.20 to dot1Q 20, and enable IP routing globally.. The configuration has three issues: 1) The native VLAN on the trunk is VLAN 1, but the switch expects VLAN 99 (common mismatch scenario). 2) Subinterface G0/0.20 uses encapsulation dot1Q 10 instead of 20, causing VLAN 20 traffic to be mis-tagged. 3) The 'ip routing' command is missing globally, so R1 cannot route between subinterfaces. To fix, configure the main interface G0/0 with 'encapsulation dot1Q 99 native' to set the native VLAN to 99, correct the encapsulation on G0/0.20 to 'dot1Q 20', and enable IP routing with 'ip routing'.

Answer

Change the native VLAN on R1's trunk interface to 99, correct the encapsulation on G0/0.20 to dot1Q 20, but do not enable IP routing because it is enabled by default.

Answer

Change the native VLAN on R1's trunk interface to 1, correct the encapsulation on G0/0.20 to dot1Q 20, and enable IP routing globally.

Answer

Change the native VLAN on R1's trunk interface to 99, correct the encapsulation on G0/0.10 to dot1Q 10, and enable IP routing globally.

Question 5

You are connected to R1. The network consists of R1, SW1, and two hosts (Host-A on VLAN 10, Host-B on VLAN 20). SW1 has two access ports (one per VLAN) and a trunk to R1. Configure R1 for router-on-a-stick inter-VLAN routing. The current configuration has a native VLAN mismatch and a missing subinterface for VLAN 20. Fix these issues so that Host-A and Host-B can ping each other.

Accepted Answer

Configure interface G0/0.20 with encapsulation dot1Q 20 and IP address 192.168.20.1 255.255.255.0, set native VLAN to 1 on the trunk, and enable ip routing.. The native VLAN mismatch exists: R1 expects native VLAN 99, but SW1 likely uses native VLAN 1 (default). This causes CDP/STP issues but not directly inter-VLAN routing; however, for proper operation, set native VLAN to 1 on R1. Additionally, the subinterface for VLAN 20 is missing, so traffic from VLAN 20 cannot be routed. Finally, 'ip routing' is disabled, preventing any inter-VLAN routing. Solution: change native VLAN on trunk to 1, create subinterface G0/0.20 with encapsulation dot1Q 20 and IP 192.168.20.1/24, and enable ip routing.

Answer

Configure interface G0/0.20 with encapsulation dot1Q 20 and IP address 192.168.20.1 255.255.255.0, set native VLAN to 99 on the trunk, and enable ip routing.

Answer

Configure interface G0/0.20 with encapsulation dot1Q 20 and IP address 192.168.20.1 255.255.255.0, set native VLAN to 1 on the trunk, but do not enable ip routing.

Answer

Configure interface G0/0.20 with encapsulation dot1Q 20 and IP address 192.168.20.1 255.255.255.0, set native VLAN to 99 on the trunk, and do not enable ip routing.

Question 6

You are connected to a multilayer switch SW1 via console. SW1 has an IP phone and an access point connected to interfaces GigabitEthernet0/1 and GigabitEthernet0/2 respectively. Configure the access ports so that the IP phone receives a voice VLAN (VLAN 110) and PoE priority critical, and the access point receives PoE priority high. Verify your configuration using show interfaces switchport and show power inline.

Accepted Answer

interface GigabitEthernet0/1
 switchport mode access
 switchport access vlan 10
 switchport voice vlan 110
 power inline priority critical
!
interface GigabitEthernet0/2
 switchport mode access
 power inline priority high. The IP phone requires a voice VLAN configured with the switchport voice vlan command. PoE priority is set per interface using power inline priority. For the phone, the priority is critical; for the AP, it is high. Verification with show interfaces switchport confirms voice VLAN, and show power inline shows priority settings.

Answer

interface GigabitEthernet0/1
 switchport mode trunk
 switchport trunk allowed vlan 10,110
 power inline priority critical
!
interface GigabitEthernet0/2
 switchport mode access
 power inline priority high

Answer

interface GigabitEthernet0/1
 switchport mode access
 switchport access vlan 110
 switchport voice vlan 10
 power inline priority critical
!
interface GigabitEthernet0/2
 switchport mode access
 power inline priority high

Answer

interface GigabitEthernet0/1
 switchport mode access
 switchport access vlan 10
 switchport voice vlan 110
 power inline priority high
!
interface GigabitEthernet0/2
 switchport mode access
 power inline priority critical

Question 7

You are connected to the console of a Catalyst 2960+ switch named SW2. Configure the switch so that the IP phone connected to interface FastEthernet0/5 receives power via PoE and uses VLAN 150 for voice traffic, while the PC connected through the phone uses VLAN 50 for data. Additionally, the access point connected to interface FastEthernet0/10 must receive PoE and be placed in VLAN 100. Assume the interfaces are already correctly configured as access ports in VLAN 50 and VLAN 100, respectively. Verify your configuration using the appropriate show commands.

Accepted Answer

On interface FastEthernet0/5: switchport voice vlan 150, power inline auto. On interface FastEthernet0/10: power inline auto. Verify with show interfaces switchport and show power inline.. The switch had no voice VLAN or PoE configured on the ports. On FastEthernet0/5, you need to add 'switchport voice vlan 150' to separate voice traffic from data, and 'power inline auto' to enable PoE for the IP phone. On FastEthernet0/10, you only need to enable PoE with 'power inline auto' because the AP already has its access VLAN set. After configuration, 'show interfaces switchport' will confirm the voice VLAN, and 'show power inline' will verify PoE status.

Answer

On interface FastEthernet0/5: switchport voice vlan 150, power inline auto. On interface FastEthernet0/10: switchport access vlan 100, power inline auto. Verify with show interfaces switchport and show power inline.

Answer

On interface FastEthernet0/5: switchport voice vlan 150, power inline auto. On interface FastEthernet0/10: power inline auto. Verify with show vlan and show power inline.

Answer

On interface FastEthernet0/5: switchport voice vlan 150, power inline auto. On interface FastEthernet0/10: power inline auto. Verify with show interfaces trunk and show power inline.

Question 8

You are connected to a single switch, SW1, which is a Cisco Catalyst 2960 running Cisco IOS. Configure port GigabitEthernet0/1 as an access port for a Cisco IP phone and a PC on the same VLAN (Voice VLAN 20, Data VLAN 10). The switch must provide PoE to the phone. Additionally, configure GigabitEthernet0/2 as an access port for a wireless access point (AP) that requires PoE. Verify both configurations using the appropriate show commands. The current running-config is incomplete; you must add the necessary commands.

Accepted Answer

interface GigabitEthernet0/1
 switchport mode access
 switchport access vlan 10
 switchport voice vlan 20
 power inline auto
interface GigabitEthernet0/2
 switchport mode access
 switchport access vlan 10
 power inline auto. The configuration was missing the voice VLAN assignment on Gi0/1 and PoE settings on both ports. For Gi0/1, the command 'switchport voice vlan 20' is required to separate voice traffic from data traffic. For both Gi0/1 and Gi0/2, PoE must be enabled; by default 'power inline auto' is set, but since the ports show 'off', they may have been disabled. The solution ensures PoE is enabled with 'power inline auto' and sets the voice VLAN correctly. Verification with 'show interfaces switchport' should show 'Voice VLAN: 20' and 'show power inline' should show 'auto' for both ports.

Answer

interface GigabitEthernet0/1
 switchport mode trunk
 switchport trunk allowed vlan 10,20
 power inline auto
interface GigabitEthernet0/2
 switchport mode access
 switchport access vlan 10
 power inline auto

Answer

interface GigabitEthernet0/1
 switchport mode access
 switchport access vlan 10
 switchport voice vlan 20
 power inline never
interface GigabitEthernet0/2
 switchport mode access
 switchport access vlan 10
 power inline auto

Answer

interface GigabitEthernet0/1
 switchport mode access
 switchport access vlan 20
 switchport voice vlan 10
 power inline auto
interface GigabitEthernet0/2
 switchport mode access
 switchport access vlan 10
 power inline auto

Question 9

You are connected to a Multilayer Switch MLS1. Configure the switch so that interface GigabitEthernet1/0/1 is an access port for VLAN 10, with voice VLAN 110 for an IP phone, and enable PoE. Additionally, interface GigabitEthernet1/0/2 must be an access port for VLAN 20 to connect an AP. Verify the configuration using 'show interfaces switchport' and 'show power inline'.

Accepted Answer

interface GigabitEthernet1/0/1
 switchport mode access
 switchport access vlan 10
 switchport voice vlan 110
 power inline auto
interface GigabitEthernet1/0/2
 switchport mode access
 switchport access vlan 20. It configures Gi1/0/1 as an access port in VLAN 10 with voice VLAN 110 and PoE enabled, and Gi1/0/2 as an access port in VLAN 20. Option B is wrong because it uses 'switchport mode trunk' instead of 'switchport mode access'. For a voice VLAN, the port should be an access port, not a trunk. Option C is wrong because it disables PoE with 'power inline never', but the IP phone requires power. Option D is wrong because it assigns the access VLAN as 110 and voice VLAN as 10, reversing the intended roles. Verify with 'show interfaces switchport' and 'show power inline'.

Answer

interface GigabitEthernet1/0/1
 switchport mode trunk
 switchport trunk allowed vlan 10,110
 power inline auto
interface GigabitEthernet1/0/2
 switchport mode access
 switchport access vlan 20

Answer

interface GigabitEthernet1/0/1
 switchport mode access
 switchport access vlan 10
 switchport voice vlan 110
 power inline never
interface GigabitEthernet1/0/2
 switchport mode access
 switchport access vlan 20

Answer

interface GigabitEthernet1/0/1
 switchport mode access
 switchport access vlan 110
 switchport voice vlan 10
 power inline auto
interface GigabitEthernet1/0/2
 switchport mode access
 switchport access vlan 20

Question 10

You are connected to a multilayer switch MLS1 via the console. Configure MLS1 so that IP phones connected to interface GigabitEthernet0/1 receive power via PoE, use VLAN 10 for data traffic, and use VLAN 20 for voice traffic, while the access port for an AP on GigabitEthernet0/2 should be placed in VLAN 30 and have PoE disabled. Verify your configuration using appropriate show commands.

Accepted Answer

interface GigabitEthernet0/1
 switchport mode access
 switchport access vlan 10
 switchport voice vlan 20
 power inline auto
!
interface GigabitEthernet0/2
 switchport mode access
 switchport access vlan 30
 power inline never. For the IP phone port (G0/1), you need to enable PoE (power inline auto) and configure the voice VLAN (switchport voice vlan 20) so that the phone uses VLAN 20 for voice and the access VLAN 10 for data. For the AP port (G0/2), you must change the access VLAN to 30 and disable PoE (power inline never) to prevent powering the AP through the switch. Verify with 'show interfaces switchport' to confirm voice VLAN and access VLAN settings, and 'show power inline' to check PoE status.

Answer

interface GigabitEthernet0/1
 switchport mode trunk
 switchport trunk allowed vlan 10,20
 power inline auto
!
interface GigabitEthernet0/2
 switchport mode access
 switchport access vlan 30
 power inline never

Answer

interface GigabitEthernet0/1
 switchport mode access
 switchport access vlan 20
 switchport voice vlan 10
 power inline auto
!
interface GigabitEthernet0/2
 switchport mode access
 switchport access vlan 30
 power inline never

Answer

interface GigabitEthernet0/1
 switchport mode access
 switchport access vlan 10
 switchport voice vlan 20
 power inline never
!
interface GigabitEthernet0/2
 switchport mode access
 switchport access vlan 30
 power inline auto

Question 11

You are connected to a multilayer switch MLS1. Configure FastEthernet0/1 as an access port for an IP phone and a PC, with voice VLAN 20 and data VLAN 10. Also enable PoE on the port. Then verify the configuration using 'show interfaces switchport' and 'show power inline'.

Accepted Answer

interface FastEthernet0/1
 switchport mode access
 switchport access vlan 10
 switchport voice vlan 20
 power inline auto
 no shutdown. It configures FastEthernet0/1 as an access port with data VLAN 10, voice VLAN 20, and PoE enabled, which is the required setup for an IP phone and PC. Option B is incorrect because 'no switchport' makes the interface a routed port (Layer 3), but it needs to be a Layer 2 access port to support an IP phone and PC. Option C is incorrect because trunk mode is used for switch-to-switch links, not for connecting end devices like an IP phone and PC. Option D is incorrect because 'power inline never' disables PoE, but the IP phone requires power; it should use 'power inline auto'.

Answer

interface FastEthernet0/1
 no switchport
 ip address 192.168.1.1 255.255.255.0
 power inline auto
 no shutdown

Answer

interface FastEthernet0/1
 switchport mode trunk
 switchport trunk allowed vlan 10,20
 power inline auto
 no shutdown

Answer

interface FastEthernet0/1
 switchport mode access
 switchport access vlan 10
 switchport voice vlan 20
 power inline never
 no shutdown

Question 12

You are connected to SW1 via the console. The network uses Rapid-PVST+ and you need to ensure that SW1 becomes the root bridge for VLAN 10 and VLAN 20. Additionally, configure PortFast and BPDU Guard on interface GigabitEthernet0/1, which connects to a workstation. After configuration, the workstation is moved and the port goes err-disabled. Diagnose the cause and recover the port without reloading the switch.

Accepted Answer

Configure spanning-tree vlan 10 priority 4096 and spanning-tree vlan 20 priority 4096. Then on interface GigabitEthernet0/1, configure spanning-tree portfast and spanning-tree bpduguard enable. After removing the BPDU source, use 'shutdown' and 'no shutdown' to recover the port.. SW1 is currently the root for VLAN 10 but not for VLAN 20. To become root for both VLANs, set the spanning-tree priority to a lower value (e.g., 4096) for each VLAN. The port Gi0/1 went err-disabled because it received a BPDU, which is unexpected on a PortFast edge port with BPDU Guard enabled. To recover, first identify and remove the BPDU source (likely another switch connected to that port), then use 'shutdown' followed by 'no shutdown' on the interface to bring it back up.

Answer

Configure spanning-tree vlan 10,20 root primary and spanning-tree portfast on Gi0/1; then use 'errdisable recovery cause bpduguard' to automatically recover the port.

Answer

Configure spanning-tree vlan 10,20 priority 0 and spanning-tree bpduguard enable on Gi0/1; then use 'no spanning-tree bpduguard' to recover the port.

Answer

Configure spanning-tree vlan 10,20 priority 4096 and spanning-tree portfast on Gi0/1; then use 'clear spanning-tree detected-protocols' to recover the port.

Question 13

You are connected to a multilayer switch MLSW1. PortFast and BPDU Guard have already been enabled on interface GigabitEthernet0/1, which connects to an end device, and a BPDU received on that interface placed it in the err-disabled state. Configure Rapid PVST+ so that MLSW1 becomes the root bridge for VLAN 10 with a priority of 4096. Recover the interface by re-enabling it. Finally, verify which port is blocking on VLAN 10 by connecting to MLSW2 and executing the appropriate show command.

Accepted Answer

spanning-tree vlan 10 priority 4096; interface GigabitEthernet0/1; shutdown; no shutdown; show spanning-tree vlan 10. The correct solution sets the spanning-tree priority for VLAN 10 to 4096 on MLSW1, ensuring it becomes the root bridge. PortFast and BPDU Guard are already configured on G0/1, which caused the interface to go err-disabled when a BPDU was received. To recover, you must issue the 'shutdown' followed by 'no shutdown' commands on the interface. Because MLSW1 is the root bridge, it has no blocking ports; the blocking port (alternate) will be seen on a downstream switch like MLSW2. Therefore, verification must be done on MLSW2 using 'show spanning-tree vlan 10' to view the alternate blocking port. Option A correctly includes all required steps. Option B uses 'root primary' (priority 24576) instead of the specified 4096, lacks the recovery commands, and verifies on the wrong device. Option C omits the err-disabled recovery and uses the wrong verification command. Option D also verifies with 'show running-config', which does not display STP port roles.

Answer

spanning-tree vlan 10 root primary; interface GigabitEthernet0/1; no shutdown; show spanning-tree vlan 10

Answer

spanning-tree vlan 10 priority 4096; interface GigabitEthernet0/1; no shutdown; show interfaces status

Answer

spanning-tree vlan 10 priority 4096; interface GigabitEthernet0/1; shutdown; no shutdown; show running-config

Question 14

You are connected to SW1. The network has experienced a spanning-tree topology change, and the new root bridge is not the intended core switch. Configure SW1 with a root primary priority, enable PortFast and BPDU Guard on interface GigabitEthernet0/3 (an edge port connected to a server), and verify that a specific port in the topology is blocking. Then, after a BPDU violation occurs on G0/3, recover the interface from err-disable state without reloading the switch.

Accepted Answer

spanning-tree vlan 1 root primary; interface GigabitEthernet0/3; spanning-tree portfast; spanning-tree bpduguard enable; interface GigabitEthernet0/3; shutdown; no shutdown. The current root bridge has priority 32769, but the intended root should be SW1 with a lower priority. First, configure SW1 as root primary using 'spanning-tree vlan 1 root primary' or manually set priority to 24576. For edge port Gi0/3, enable PortFast with 'spanning-tree portfast' and BPDU Guard with 'spanning-tree bpduguard enable'. After the BPDU violation, the port is err-disabled. To recover, first shut down and then no shut the interface, or use 'errdisable recovery cause bpduguard' and wait for the recovery interval, but the most direct method is to manually bounce the interface.

Answer

spanning-tree vlan 1 priority 4096; interface GigabitEthernet0/3; spanning-tree portfast; spanning-tree bpduguard enable; interface GigabitEthernet0/3; errdisable recovery cause bpduguard

Answer

spanning-tree vlan 1 root secondary; interface GigabitEthernet0/3; spanning-tree portfast; spanning-tree bpduguard enable; interface GigabitEthernet0/3; no shutdown

Answer

spanning-tree vlan 1 root primary; interface GigabitEthernet0/3; spanning-tree portfast; spanning-tree bpdufilter enable; interface GigabitEthernet0/3; shutdown; no shutdown

Question 15

You are connected to a multilayer switch MLS1. The network has two other switches: SW2 and SW3. The interface GigabitEthernet0/1 already has PortFast and BPDU Guard enabled. Configure MLS1 as the root bridge for VLAN 10 and VLAN 20 using the root primary command. After configuration, verify that the interface is not in err-disabled state and that the root bridge role is correctly assigned.

Accepted Answer

Configure 'spanning-tree vlan 10 root primary' and 'spanning-tree vlan 20 root primary' on MLS1. Verify with 'show spanning-tree vlan 10' and 'show interfaces gigabitEthernet0/1 status'.. The interface Gi0/1 already has PortFast and BPDU Guard configured, so no additional configuration is needed for that step. Using 'spanning-tree vlan 10 root primary' and 'spanning-tree vlan 20 root primary' sets the priority to 24576, ensuring MLS1 becomes root for both VLANs. Verify with 'show spanning-tree vlan 10' to see the priority changed and 'show interfaces gigabitEthernet0/1 status' to confirm the port is not err-disabled.

Answer

Configure 'spanning-tree vlan 10 root primary' and 'spanning-tree vlan 20 root secondary' on MLS1. Verify with 'show spanning-tree vlan 10' and 'show interfaces gigabitEthernet0/1 status'.

Answer

Configure 'spanning-tree vlan 10 priority 4096' and 'spanning-tree vlan 20 priority 4096' on MLS1. Verify with 'show spanning-tree vlan 10' and 'show interfaces gigabitEthernet0/1 status'.

Answer

Configure 'spanning-tree vlan 10 root primary' and 'spanning-tree vlan 20 root primary' on MLS1. Then configure 'spanning-tree portfast default' and 'spanning-tree bpduguard default' globally. Verify with 'show spanning-tree vlan 10' and 'show interfaces gigabitEthernet0/1 status'.