CCNA Switching and Network Access Practice Test 18 — 15 Questions

Question 1

Drag and drop the following steps into the correct order to configure Root Guard on designated ports, Loop Guard on non-designated ports, and BPDU Guard on PortFast ports, and then recover a port that enters err-disabled due to BPDU Guard.

Accepted Answer

1. Configure Root Guard on designated ports. 2. Configure Loop Guard on non-designated ports. 3. Configure BPDU Guard on PortFast ports. 4. Recover a port in err-disabled state due to BPDU Guard by shutting it down and re-enabling it.. The correct order begins with Root Guard on designated ports to prevent them from becoming root ports upon receiving superior BPDUs. Next, Loop Guard is applied to non-designated ports (alternate/backup) to protect against unidirectional link failures. Then, BPDU Guard is placed on PortFast-enabled ports to shut them down if a BPDU is received, preventing rogue switch connections. Finally, recovery from BPDU Guard err-disable requires a manual interface reset (shutdown/no shutdown) because the errdisable cause 'bpduguard' has no automatic timeout.

Question 2

Which TWO statements correctly describe the configuration and effect of Root Guard and BPDU Guard on a Cisco switch?

Accepted Answer

Root Guard is configured on a per-port basis and causes the port to become root-inconsistent if a superior BPDU is received.. Option A is correct because Root Guard is configured per interface using the 'spanning-tree guard root' command. When a port with Root Guard enabled receives a superior BPDU (one that would cause the switch to become a non-root bridge), the port is placed into a root-inconsistent state, effectively blocking traffic on that port and preventing the switch from accepting a new root bridge from that direction. This protects the spanning-tree topology from unauthorized or misconfigured switches attempting to become the root bridge. Option D is correct because BPDU Guard is commonly enabled on ports with PortFast (typically access ports connected to end devices). When a BPDU is received on such a port, BPDU Guard places the port into errdisable state, preventing potential bridging loops that could result from an unauthorized switch connecting to the network. Option B is incorrect because BPDU Guard does not prevent loops by disabling a trunk port; it is typically used on access ports (often with PortFast) and disables the port upon receiving any BPDU, not just on trunk ports. Option C is incorrect because Root Guard places the port into root-inconsistent state (not errdisable) when a superior BPDU is received; BPDU Guard uses errdisable. Option E is incorrect because neither Root Guard nor BPDU Guard filters BPDUs; Root Guard reacts to superior BPDUs by blocking the port, and BPDU Guard reacts to any BPDU by disabling the port. Both features allow BPDUs to be processed but then take action based on the received BPDUs.

Answer

BPDU Guard prevents loops by disabling a trunk port that receives a BPDU from an unauthorized switch.

Answer

Root Guard places a port in errdisable state when a superior BPDU is received.

Answer

Both Root Guard and BPDU Guard filter BPDUs to prevent them from being processed by the switch CPU.

Question 3

Drag and drop the following steps into the correct order to configure an LACP EtherChannel on Cisco IOS-XE switches.

Accepted Answer

Enter global configuration mode, create the port-channel interface, configure channel-group mode active on each physical interface, verify the configuration.. First, enter global config mode. Then create the port-channel interface. Next, configure the channel-group mode on each physical interface to active for LACP. Finally, verify the configuration.

Answer

Create the port-channel interface, enter global configuration mode, configure channel-group mode active on each physical interface, verify the configuration.

Answer

Enter global configuration mode, configure channel-group mode active on each physical interface, create the port-channel interface, verify the configuration.

Answer

Create the port-channel interface, configure channel-group mode active on each physical interface, enter global configuration mode, verify the configuration.

Question 4

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

Accepted Answer

Create the port-channel interface, configure its properties, then assign physical interfaces with channel-group active mode.. First create the logical port-channel interface and configure its properties, then assign physical interfaces to it using channel-group with active mode to initiate LACP negotiation.

Answer

Assign physical interfaces with channel-group active mode, then create the port-channel interface and configure its properties.

Answer

Configure physical interfaces with channel-group passive mode, then create the port-channel interface.

Answer

Create the port-channel interface, assign physical interfaces with channel-group desirable mode, then configure properties.

Question 5

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 6

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

Accepted Answer

Enter global configuration mode, select the interfaces to be part of the EtherChannel, set the channel-group mode to active on both switches, and verify the configuration.. Start in global config, select interfaces, set channel-group mode to active on each interface (at least one side must be active; the other can be active or passive), then verify. This order ensures consistent negotiation and correct channel formation.

Question 7

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

Accepted Answer

Enter global configuration mode on both switches.. To configure LACP EtherChannel, start by entering global configuration mode on both switches. Then create the port-channel interface using 'interface port-channel' (optional but good practice). Finally, assign physical interfaces to the port-channel with LACP active mode using the 'channel-group' command, which handles both port binding and mode setting in one step. Verify with 'show etherchannel summary'.

Question 8

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

Accepted Answer

Configure the interface range. The correct order begins with configuring the interface range because the channel-group command must be issued under interface configuration mode. Then, set the channel-group mode to active to enable LACP active negotiation on both switches. Finally, verify the EtherChannel status using 'show etherchannel summary' to confirm the channel is up and using LACP. Option C uses passive mode, which would not initiate negotiation as required; option D uses 'show interfaces status', which does not display EtherChannel-specific information.

Question 9

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 10

You are connected to R1. The network has three departments: Sales (VLAN 10, 192.168.1.0/24), Engineering (VLAN 20, 192.168.2.0/24), and Management (VLAN 99, 192.168.99.0/24). A single switch SW1 connects to R1 via trunk interface G0/0. Subinterfaces for VLANs 10, 20, and 99 are already configured on R1 with correct encapsulation and IP addresses. However, inter-VLAN communication is failing. Troubleshoot and fix the configuration issue on R1 to enable routing between all VLANs.

Accepted Answer

Enable 'ip routing' globally on R1.. The router has correctly configured subinterfaces with 802.1Q encapsulation and IP addresses for VLANs 10, 20, and 99. However, 'ip routing' is disabled globally, so the router cannot forward packets between subinterfaces. Additionally, the native VLAN on the trunk is VLAN 1, but no subinterface for VLAN 1 is configured, and the native VLAN mismatch could cause issues; however, the main problem is the lack of IP routing. Enable 'ip routing' globally and optionally configure a subinterface for the native VLAN if needed. The solution requires only 'ip routing' to enable inter-VLAN routing.

Answer

Configure a subinterface for VLAN 1 and assign it an IP address.

Answer

Change the encapsulation on the subinterfaces from dot1Q to ISL.

Answer

Add a static route on R1 pointing to each VLAN subnet.

Question 11

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 12

You are connected to R1. The network consists of R1, a router, and SW1, a Layer 2 switch. VLANs 10 (192.168.10.0/24) and 20 (192.168.20.0/24) are configured on SW1 with hosts in each VLAN. R1 must perform inter-VLAN routing using a router-on-a-stick configuration on interface G0/0. Currently, hosts in VLAN 10 cannot ping hosts in VLAN 20. Configure R1 and identify and resolve the issue.

Accepted Answer

Enable IP routing on R1 with the 'ip routing' global configuration command.. The problem is that R1 is missing the 'ip routing' command, which is required to enable IP routing on a router. Without it, R1 cannot forward packets between the subinterfaces. Additionally, the trunk between R1 and SW1 may not be operational because R1's physical interface G0/0 has no IP address and is not set to trunk mode (though subinterfaces handle encapsulation). The solution is to enable IP routing globally and ensure the physical interface is up (no shutdown).

Answer

Configure the physical interface G0/0 with an IP address and enable trunking with 'switchport mode trunk'.

Answer

Ensure the trunk between R1 and SW1 is configured with 'switchport trunk allowed vlan 10,20' on SW1.

Answer

Add the 'no shutdown' command on R1's subinterfaces G0/0.10 and G0/0.20.

Question 13

You are connected to R1. The network uses a router-on-a-stick design with a single switch (SW1) and two VLANs: VLAN 10 (10.0.10.0/24) and VLAN 20 (10.0.20.0/24). The current configuration has connectivity issues: PCs in VLAN 20 cannot ping the router interface or each other, and there is a native VLAN mismatch on the trunk. Configure R1 to correct the native VLAN mismatch, ensure the trunk allows both VLANs, enable inter-VLAN routing, and fix any subinterface encapsulation errors so that all PCs can reach the router and each other across VLANs.

Accepted Answer

interface gig0/0
no shutdown
switchport trunk native vlan 99
switchport trunk allowed vlan 10,20
ip routing. The issue is a native VLAN mismatch: R1 subinterface .99 uses native VLAN 99, but the switch expects native VLAN 1 (default). Additionally, VLAN 20 traffic may be blocked if the switch trunk does not allow VLAN 20, and 'ip routing' is missing on R1 (though it appears to have routes, but the command may not be present). The fix: on R1, set the native VLAN on the physical interface to 99 (or match switch), ensure the trunk allows VLANs 10 and 20, and enable IP routing. Also verify subinterface encapsulation is correct. In this case, the candidate must issue 'interface gig0/0', 'no shutdown', 'switchport trunk native vlan 99', 'switchport trunk allowed vlan 10,20', and 'ip routing'.

Answer

interface gig0/0.10
encapsulation dot1Q 10
ip address 10.0.10.1 255.255.255.0
interface gig0/0.20
encapsulation dot1Q 20
ip address 10.0.20.1 255.255.255.0

Answer

interface gig0/0
no shutdown
switchport trunk native vlan 1
switchport trunk allowed vlan 10,20
ip routing

Answer

interface gig0/0
no shutdown
switchport trunk native vlan 99
switchport trunk allowed vlan 10,20
no ip routing

Question 14

You are connected to R1. The network consists of R1, SW1, and two VLANs (10 and 20). SW1 has hosts in VLAN 10 and VLAN 20 connected to its access ports. Configure R1 for router-on-a-stick inter-VLAN routing using subinterfaces on G0/0. The physical interface G0/0 is administratively up (no shutdown). The current configuration is incomplete and has errors preventing communication between the VLANs. Fix the configuration so that hosts in VLAN 10 (192.168.10.0/24) and VLAN 20 (192.168.20.0/24) can ping each other through R1.

Accepted Answer

Enable IP routing with the 'ip routing' global configuration command.. The primary fault is that IP routing is disabled globally on R1 (missing 'ip routing' command), so even though subinterfaces are correctly configured, the router cannot route between VLANs. The physical interface G0/0 is already administratively up, so issuing 'no shutdown' would not fix the problem. Thus, enabling 'ip routing' resolves the inter-VLAN communication issue. The other options either incorrectly swap encapsulation or address a native VLAN scenario not indicated in the exhibit.

Answer

Change the encapsulation on subinterface G0/0.10 to dot1Q 20 and on G0/0.20 to dot1Q 10.

Answer

Add the 'no shutdown' command on the physical interface G0/0.

Answer

Configure the native VLAN on the trunk to match the subinterface for VLAN 1.

Question 15

You are connected to R1. Configure router-on-a-stick inter-VLAN routing so that hosts in VLAN 10 and VLAN 20 can communicate through R1. The switch (not shown) is already configured with the correct VLANs and trunk. Troubleshoot and fix any issues in the current R1 configuration.

Accepted Answer

Enable IP routing globally and bring up the main interface GigabitEthernet0/0 with 'no shutdown'.. The R1 configuration has two subinterfaces (G0/0.10 and G0/0.20) with correct VLAN encapsulation and IP addresses, but inter-VLAN routing fails because the main interface G0/0 is not configured as a trunk (no 'no shutdown' and no 'ip routing' globally). Enable IP routing globally with 'ip routing' and ensure GigabitEthernet0/0 is administratively up with 'no shutdown'. The subinterfaces will then route between VLANs.

Answer

Change the encapsulation on the subinterfaces to 'encapsulation dot1Q 10 native' and 'encapsulation dot1Q 20 native'.

Answer

Remove the subinterfaces and configure IP addresses directly on GigabitEthernet0/0.

Answer

Add 'ip routing' on each subinterface individually.