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Network Access

400 questions

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Question 361Question →

A network administrator executes the command `show interfaces gigabitethernet0/2 switchport` on a Cisco Catalyst switch to troubleshoot a connectivity issue for an end-user device. The CLI output displays the following operational state:

text
Name: Gi0/2
Switchport: Enabled
Administrative Mode: dynamic auto
Operational Mode: trunk
Access Mode VLAN: 20 (VLAN0020)
Trunking Native Mode VLAN: 1 (default)

Which command must be configured on interface GigabitEthernet0/2 to force the port to operate as an access port in VLAN 20?

Show answer & explanation

Answer: switchport mode access

Answer

The command `switchport mode access` must be configured on interface GigabitEthernet0/2.
The CLI output indicates that interface GigabitEthernet0/2 has an Administrative Mode of 'dynamic auto' and has negotiated an Operational Mode of 'trunk'. Even though an access VLAN of 20 is configured, access VLAN assignments only take effect when the operational mode is access. Executing `switchport mode access` under interface configuration mode statically sets the interface to access mode and disables trunking negotiation.

Step-by-Step Solution

1
Analyze the CLI output for interface GigabitEthernet0/2
Administrative Mode is set to 'dynamic auto' and Operational Mode is currently operating as 'trunk'.
By default on many Cisco Catalyst switches, interfaces run Dynamic Trunking Protocol (DTP) in dynamic auto mode. If the connected device sends DTP frames or negotiates trunking, the interface operates as a trunk regardless of the configured access VLAN.
2
Determine the required command to override dynamic negotiation
Configuring `switchport mode access` under `interface GigabitEthernet0/2` forces the interface to operate statically as an access port.
Statically defining the port mode as access disables trunk negotiation for that port and activates the configured `switchport access vlan 20` setting.

Key Concept

Disabling DTP trunk negotiation by statically configuring access port mode with 'switchport mode access'.
Question 362Question →

During a network outage, a centralized Wireless LAN Controller (WLC) becomes completely unreachable from the campus network. Several Cisco Lightweight Access Points (LAPs) in the facility are configured in standard Local mode. How do these Local mode APs handle connected wireless clients while WLC connectivity is lost?

Show answer & explanation

Answer: They drop all client associations and stop forwarding data traffic because an active CAPWAP tunnel to the controller is required for operation.

Answer

Local mode APs drop all client associations and stop forwarding data traffic because an active CAPWAP tunnel to the controller is required for operation.
In standard Local mode, a Cisco Lightweight Access Point routes all control and data traffic through CAPWAP tunnels back to the Wireless LAN Controller (centralized switching). If the WLC becomes unreachable, the CAPWAP tunnel collapses, causing the AP to drop all client associations, stop serving WLANs, and reboot/search for an accessible WLC.

Step-by-Step Solution

1
Analyze the operational behavior of Cisco Lightweight Access Points in standard Local mode.
Local mode is the default AP mode where all wireless user traffic is encapsulated into CAPWAP data packets and sent directly to the Wireless LAN Controller (centralized switching).
Control and data plane functions rely entirely on the active CAPWAP connection between the AP and WLC.
2
Determine the outcome when the WLC becomes completely unreachable.
Without a responsive WLC, the CAPWAP control tunnel drops. The Local mode AP cannot process client frames locally nor manage client authentication.
Unlike FlexConnect mode, Local mode APs cannot operate in a standalone state.
3
Identify the correct impact on client connectivity.
The AP drops all associated clients and continuously attempts to discover and rejoin a WLC.
Wireless service is completely interrupted until WLC connectivity is restored.

Key Concept

Cisco Lightweight Access Point Local Mode vs FlexConnect Mode Behavior During WLC Outage
Question 363Question →

A switch running Rapid PVST+ receives BPDUs across multiple active interfaces and must determine which port will assume the Root Port role for a specific VLAN. Place the decision criteria evaluated by the switch in the correct sequential order, starting from the first criterion evaluated to the last.

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Answer

The correct sequence for selecting a Rapid PVST+ Root Port is: 1. Lowest cumulative Root Path Cost to the Root Bridge, 2. Lowest upstream neighbor Bridge ID (Sender BID), 3. Lowest upstream neighbor Port ID (Sender Port ID), 4. Lowest local Port ID on the receiving switch.
When selecting a Root Port, a Rapid PVST+ non-root switch evaluates received BPDU criteria in a strict hierarchical order: cumulative Root Path Cost first, followed by sender Bridge ID, sender Port ID, and finally local Port ID.

Step-by-Step Solution

1
Evaluate path efficiency
Identify the interface with the lowest cumulative cost to reach the Root Bridge.
STP prioritizes path efficiency before comparing device or port identifiers.
2
Evaluate upstream device identity
If path costs are equal, compare the Bridge IDs of the neighboring switches sending the BPDUs.
Connecting to a neighbor with a lower Bridge ID takes precedence when costs match.
3
Evaluate upstream port identity
If connected via multiple links to the same upstream switch, compare the Port IDs (port priority + port number) transmitted by the neighbor.
The upstream switch's lower sending port ID breaks ties for parallel links to the same neighbor.
4
Evaluate local port identity
If all received BPDU fields are identical, compare the local receiving switch's Port IDs.
The local switch uses its own lowest port ID as the final deterministic tie-breaker.

Key Concept

Rapid PVST+ Root Port Selection Algorithm
Estimated Time:1m 30s
Question 364Question →

A network administrator needs to create a new VLAN for isolated guest traffic (VLAN 80, named GUEST) on a Cisco Catalyst switch and configure interface GigabitEthernet0/12 as a static access port belonging to this VLAN. In what sequence should the administrator execute the CLI commands starting from Privileged EXEC mode?

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Answer

The correct sequence starts with 'configure terminal' to enter global configuration mode, followed by 'vlan 80' to create the VLAN, 'name GUEST' to name it, 'interface GigabitEthernet0/12' to enter interface mode, 'switchport mode access' to define the port mode, and 'switchport access vlan 80' to assign the port to the VLAN.
Configuring a VLAN and access port requires following Cisco IOS mode hierarchy: starting in Privileged EXEC mode, entering Global Configuration mode via 'configure terminal', instantiating VLAN 80 with 'vlan 80', assigning its label with 'name GUEST', navigating to the target port via 'interface GigabitEthernet0/12', locking its operational state with 'switchport mode access', and assigning it to the newly created VLAN with 'switchport access vlan 80'.

Step-by-Step Solution

1
Enter Global Configuration mode
Switch prompt changes to Switch(config)#
CLI commands for creating VLANs and accessing interfaces require global configuration context.
2
Create VLAN 80
Switch prompt changes to Switch(config-vlan)#
VLAN 80 must be created before naming or assigning interfaces to it.
3
Name the VLAN GUEST
VLAN 80 is assigned the name GUEST in the database
The name sub-command must be executed within config-vlan mode.
4
Select interface GigabitEthernet0/12
Switch prompt changes to Switch(config-if)#
Interface configuration mode is required to apply port-specific switchport commands.
5
Configure operational mode as access
DTP negotiation is disabled for trunking and port is forced to access mode
Disabling dynamic trunking negotiation ensures the port functions strictly as an access port.
6
Assign the interface to VLAN 80
Interface GigabitEthernet0/12 is placed into VLAN 80 broadcast domain
Associates untagged ingress frames on GigabitEthernet0/12 with VLAN 80.

Key Concept

Cisco IOS CLI command hierarchy and sequence for creating a VLAN and configuring an access port.
Estimated Time:1m 30s
Question 365Question →

Match each Cisco Lightweight Access Point (LAP) operational mode to its correct primary functional description.

Click a left item, then click its matching right item

Items

FlexConnect Mode
Sniffer Mode
SE-Connect Mode
Rogue Detector Mode

Matches

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Answer

FlexConnect Mode matches local traffic switching during WAN outages; Sniffer Mode matches capturing raw 802.11 frames for packet analyzers; SE-Connect Mode matches sending raw RF data to spectrum analysis tools; Rogue Detector Mode matches correlating wireless and wired MAC addresses to find unauthorized devices.
Each mode serves a distinct operational purpose: FlexConnect allows branch local traffic switching without reliance on a persistent CAPWAP tunnel for user data. Sniffer mode captures raw 802.11 frames to send to network analysis tools like Wireshark. SE-Connect streams raw physical spectrum metrics to software tools like Cisco Spectrum Expert. Rogue Detector correlates MAC addresses from wired switch ports and rogue AP broadcasts to detect connected unauthorized access points.

Step-by-Step Solution

1
Identify the primary purpose of FlexConnect mode in remote branch environments.
FlexConnect allows local data switching and client authentication even if the WAN tunnel to the controller drops.
This maintains survivability for branch wireless networks.
2
Determine the role of Sniffer mode versus SE-Connect mode.
Sniffer captures 802.11 layer 2 wireless frames for packet analyzer software, whereas SE-Connect captures layer 1 RF physical layer data for Cisco Spectrum Expert software.
Sniffer works at the frame/packet level while SE-Connect analyzes raw radio frequency interference.
3
Evaluate Rogue Detector mode operational behavior.
Rogue Detector APs do not serve client traffic on radios; instead, they monitor wired ARP/MAC tables to verify if rogue devices seen wirelessly are connected to the internal wired subnet.
Correlating wired MACs with wireless MACs isolates rogue APs physically connected to the enterprise network.

Key Concept

Cisco Access Point Operational Modes
Question 366Question →

A network administrator is configuring Rapid PVST+ on a Cisco Catalyst switch. The administrator wants the switch to achieve a total Bridge Identifier (BID) priority of 1648416484 for VLAN 100100. Which Cisco IOS command correctly sets the base priority to accomplish this target total priority?

Show answer & explanation

Answer: spanning-tree vlan 100 priority 16384

Answer

The command 'spanning-tree vlan 100 priority 16384' correctly sets the base bridge priority.
In Rapid PVST+, the total Bridge Identifier (BID) priority is the sum of the base bridge priority and the System ID Extension (which equals the VLAN ID). To achieve a total priority of 1648416484 in VLAN 100100, the base priority must be configured as 1638416384 (16384+100=1648416384 + 100 = 16484). Base priorities must be configured in multiples of 40964096.

Step-by-Step Solution

1
Calculate the required base bridge priority
Base Priority = Total BID Priority - System ID Extension (VLAN ID) = 16484−100=1638416484 - 100 = 16384
Rapid PVST+ automatically appends the VLAN ID (System ID Extension) to the base bridge priority to form the final BID priority.
2
Verify priority increment rules
16384=4096×416384 = 4096 \times 4, which is a valid priority increment
Cisco IOS requires the base STP priority value to be configured in steps of 4096.
3
Formulate the correct Cisco IOS configuration syntax
spanning-tree vlan 100 priority 16384
The command syntax specifies the base priority without manually adding the VLAN ID.

Key Concept

Rapid PVST+ System ID Extension and Base Priority Increments
Question 367Question →

An administrator issues the global configuration command `spanning-tree vlan 50 priority 28672` on a switch running Rapid PVST+. What total Bridge Priority value will be populated in the Bridge Identifier (BID) field of outgoing BPDUs for VLAN 50?

Show answer & explanation

Answer: 28722

Answer

28722
Rapid PVST+ utilizes the IEEE 802.1t System ID Extension by default. The 16-bit priority portion of the Bridge Identifier (BID) is calculated by taking the configured 4-bit base priority (which must be a multiple of 4096) and adding the 12-bit VLAN ID (System ID Extension). Adding VLAN ID 50 to the configured base priority of 28672 produces a total Bridge Priority of 28722.

Step-by-Step Solution

1
Identify the base priority configured for the VLAN
The configured base priority is 28672.
The command `spanning-tree vlan 50 priority 28672` sets the base bridge priority for VLAN 50.
2
Identify the System ID Extension value
The System ID Extension value is 50.
In Rapid PVST+, the System ID Extension field automatically carries the 12-bit VLAN ID.
3
Calculate the total Bridge Priority field in the Bridge Identifier (BID)
Total Bridge Priority = 28672 + 50 = 28722.
The 16-bit priority portion of the BID is composed of the 4-bit base priority multiplier plus the 12-bit System ID Extension.

Key Concept

Rapid PVST+ Bridge Identifier (BID) Structure and System ID Extension
Estimated Time:1m 0s
Question 368Question →

An enterprise deploys a Cisco Lightweight Access Point (LAP) operating in FlexConnect mode at a remote branch office. The AP is configured to perform local switching for WLANs mapped to VLAN 10 (Sales) and VLAN 20 (Guests). The AP management traffic must be assigned to VLAN 100 and transmitted untagged over the physical link. The connected Cisco Catalyst switch port is configured as an 802.1Q trunk. Which switchport configuration command must be applied to the switch port to ensure AP management traffic and locally switched WLAN traffic function properly?

Show answer & explanation

Answer: switchport trunk native vlan 100

Answer

The switch interface must be configured with 'switchport trunk native vlan 100'.
When a Cisco Lightweight AP in FlexConnect mode is configured for local traffic switching across multiple VLANs (VLAN 10 and VLAN 20), the switch port must be an 802.1Q trunk. Because the AP sends its management traffic untagged by default, the switch port's native VLAN must match the AP's management VLAN (VLAN 100). The command 'switchport trunk native vlan 100' ensures untagged management frames are mapped into VLAN 100 while carrying tagged frames for the client VLANs.

Step-by-Step Solution

1
Identify the AP deployment mode and traffic requirements.
The AP operates in FlexConnect mode with local switching for VLAN 10 and VLAN 20, requiring an 802.1Q trunk port.
FlexConnect APs supporting multiple locally switched SSIDs mapped to different VLANs must connect to switch ports configured as 802.1Q trunks.
2
Determine how the AP management traffic is framed.
AP management traffic is assigned to VLAN 100 and sent untagged by default.
Cisco Lightweight APs send their CAPWAP management traffic untagged unless AP VLAN tagging is explicitly enabled.
3
Select the appropriate 802.1Q trunk configuration command.
Apply 'switchport trunk native vlan 100' on the switch port.
Setting the native VLAN to 100 ensures untagged frames received from the AP are mapped to VLAN 100 on the switch, while tagged frames for VLAN 10 and VLAN 20 are trunked appropriately.

Key Concept

FlexConnect AP Switch Port Infrastructure Trunking and Native VLAN Configuration
Estimated Time:1m 30s
Question 369Question →

A network administrator is connecting a new IP security camera to interface GigabitEthernet1/0/4 on a Cisco Catalyst switch. VLAN 22 (named CAMERAS) has already been created in global configuration mode. Which set of interface configuration commands correctly configures GigabitEthernet1/0/4 to operate as a static, untagged access port belonging to VLAN 22?

Show answer & explanation

Answer: switchport mode access
switchport access vlan 22

Answer

The command sequence incorporating 'switchport mode access' followed by 'switchport access vlan 22' correctly configures the interface as a static access port assigned to VLAN 22.
To configure a switch port for a dedicated end device in Cisco IOS, the port must be explicitly configured as an access port using 'switchport mode access' and assigned to the intended broadcast domain using 'switchport access vlan <vlan-id>'. The command sequence combining 'switchport mode access' and 'switchport access vlan 22' fulfills both requirements cleanly.

Step-by-Step Solution

1
Identify the target operating mode for an end-user device or host
End-host devices such as IP cameras require an access port (single untagged VLAN membership) rather than a trunk port.
Access ports send and receive standard, untagged Ethernet frames expected by end stations.
2
Set the switchport mode to static access
Executing 'switchport mode access' under interface configuration mode disables dynamic trunking negotiation and locks the port in access mode.
This prevents unexpected DTP trunk negotiation and enforces Layer 2 static access port behavior.
3
Assign the designated access VLAN to the interface
Executing 'switchport access vlan 22' places untagged frames received on GigabitEthernet1/0/4 into VLAN 22.
This explicitly maps the port's Layer 2 broadcast domain membership to VLAN 22.

Key Concept

Configuring Cisco IOS Layer 2 Switchports as Static VLAN Access Ports
Question 370Question →

A network administrator is connecting a Cisco Wireless LAN Controller (WLC) to an upstream Cisco Catalyst switch using multiple physical distribution system ports. To increase throughput and provide interface redundancy, the administrator enables Link Aggregation (LAG) on the controller. Which two configuration requirements must be met on the upstream switch to support proper EtherChannel operation with the WLC? (Select two.)

Select all that apply

Show answer & explanation

Answer: All physical switch interfaces connected to the WLC distribution ports must be grouped into a single EtherChannel interface.; The switch ports connected to the WLC physical ports must be configured with identical attributes, including 802.1Q trunking mode and allowed VLAN lists.

Answer

The upstream switch must group all physical interfaces connected to the controller into a single EtherChannel bundle, and all member switch ports must share identical trunking and VLAN configurations.
When Link Aggregation (LAG) is enabled on a Cisco Wireless LAN Controller, all physical distribution system ports are combined into a single logical link. Consequently, the connected upstream switch must aggregate all corresponding physical ports into a single matching EtherChannel (port-channel) group. Additionally, because EtherChannel bundle members must operate with consistent interface parameters, all participating switch ports must share identical configuration attributes, such as 802.1Q trunk mode and allowed VLAN lists.

Step-by-Step Solution

1
Analyze WLC Link Aggregation (LAG) behavioral requirements.
Enabling LAG on a Cisco WLC merges all physical distribution system ports into a single logical link for load distribution and failover.
Because the controller treats all connected ports as one logical interface, the upstream switch must mirror this behavior by assigning all connected ports to a single switchport EtherChannel (port-channel) group.
2
Verify switchport trunking requirements for WLC infrastructure connections.
Member switch ports in an EtherChannel must match in configuration parameters (speed, duplex, 802.1Q trunking mode, and allowed VLANs).
Since WLC interfaces transport multiple VLANs corresponding to different SSIDs and management interfaces, the underlying port-channel and its physical member ports must be configured as 802.1Q trunks with consistent attributes.

Key Concept

WLAN Infrastructure Connections and Switch Link Aggregation (LAG)
Estimated Time:1m 30s
Question 371Question →

A non-root Cisco Catalyst switch running Rapid PVST+ receives BPDUs on multiple interfaces connected to neighboring switches for VLAN 20. The switch must determine which of its interfaces will become the single Root Port for VLAN 20. Place the tie-breaking steps evaluated by Rapid PVST+ in the exact sequential order from first step evaluated to last step evaluated.

Drag items to arrange them in the correct order

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Answer

The correct order of tie-breaking evaluation for Rapid PVST+ Root Port selection is: 1. Lowest cumulative Root Path Cost, 2. Lowest Sender Bridge ID (BID), 3. Lowest Sender Port ID, 4. Lowest local Receiver Port ID.
Rapid PVST+ evaluates Root Port selection using a strict four-step tie-breaker hierarchy: 1. Lowest cumulative Root Path Cost, 2. Lowest Sender Bridge ID (BID), 3. Lowest Sender Port ID (neighbor's port priority and index), 4. Lowest Receiver Port ID (local port priority and index).

Step-by-Step Solution

1
Identify the primary STP metric for Root Port selection.
The switch calculates total path cost by adding link costs to reach the Root Bridge. Lowest cumulative path cost is evaluated first.
STP prioritizes reaching the Root Bridge via the least costly path.
2
Apply the first tie-breaker if path costs are equal.
The switch evaluates the Sender Bridge ID (Bridge Priority + Extended System ID + MAC address) of the upstream neighbor switches.
Preferring the neighbor with the lowest Bridge ID ensures a deterministic loop-free structure.
3
Apply the second tie-breaker if path costs and neighbor BIDs are equal.
The switch checks the Sender Port ID (Port Priority + Port Number) advertised in the BPDU by the neighbor switch.
This differentiates multiple parallel links connecting to the exact same neighbor switch.
4
Apply the final tie-breaker if all upstream BPDU fields are identical.
The switch selects its own local interface with the lowest Port ID.
Local port ID is the final fallback when upstream BPDU data offers no difference.

Key Concept

Rapid PVST+ Root Port Tie-Breaking Sequence
Question 372Question →

A network administrator is connecting four physical distribution system ports of a Cisco AireOS Wireless LAN Controller to an upstream Cisco Catalyst switch. Link Aggregation (LAG) is enabled on the controller to increase bandwidth and provide redundancy. Which port-channel configuration must be applied to the upstream Catalyst switch interfaces?

Show answer & explanation

Answer: Configure all connected switch interfaces into a single port-channel group using static mode 'on' with 802.1Q trunking enabled.

Answer

Configure all connected switch interfaces into a single port-channel group using static mode 'on' with 802.1Q trunking enabled.
When LAG is enabled on a Cisco AireOS Wireless LAN Controller, all physical distribution system ports are bundled into a single logical interface. The connected Cisco Catalyst switch must be configured with all corresponding physical ports in a single EtherChannel port-channel set to static mode 'on' and operating as an 802.1Q trunk.

Step-by-Step Solution

1
Identify the Link Aggregation (LAG) characteristics supported on Cisco AireOS Wireless LAN Controllers.
AireOS controllers support LAG only as a single logical EtherChannel bundle across all distribution system ports, requiring static EtherChannel mode ('on') without dynamic negotiation protocols (LACP/PAgP).
The controller software architecture requires all physical DS ports to participate in a single static EtherChannel bundle.
2
Determine switchport encapsulation and trunking requirements for WLC connectivity.
The switchport interface connecting to the WLC LAG bundle must be an 802.1Q trunk port to transport management and WLAN VLAN traffic.
Wireless controllers handle multiple wireless networks mapped to separate 802.1Q VLAN tags.

Key Concept

WLAN Infrastructure Connections and WLC LAG Switch Configuration
Estimated Time:1m 30s
Question 373Question →

An administrator must move a workstation connected to interface FastEthernet0/11 on a Cisco Catalyst switch into VLAN 40 (named MARKETING). VLAN 40 has not yet been created on the switch. Which command sequence correctly creates the VLAN with its name and configures the port as an access port in VLAN 40?

Show answer & explanation

Answer: vlan 40
name MARKETING
exit
interface FastEthernet0/11
switchport mode access
switchport access vlan 40

Answer

The correct sequence creates VLAN 40, assigns the name MARKETING in VLAN configuration mode, configures interface FastEthernet0/11 in access mode, and assigns FastEthernet0/11 to VLAN 40.
Creating a VLAN requires entering VLAN configuration mode using 'vlan 40' and naming it with 'name MARKETING'. Configuring an access port requires navigating to the target interface, explicitly defining the switchport mode as access with 'switchport mode access', and assigning the access VLAN with 'switchport access vlan 40'.

Step-by-Step Solution

1
Create and name the VLAN in global configuration mode
VLAN 40 is created with the name MARKETING
VLANs must be defined in the VLAN database via global/VLAN configuration mode before or during assignment.
2
Enter interface configuration mode for FastEthernet0/11
Prompt changes to Switch(config-if)#
Interface parameters can only be altered in interface configuration mode.
3
Set port mode to access and assign VLAN 40
Interface FastEthernet0/11 operates as an access port assigned to VLAN 40
'switchport mode access' explicitly defines the port role for end devices, and 'switchport access vlan 40' places untagged ingress frames into VLAN 40.

Key Concept

VLAN Creation and Access Port Assignment in Cisco IOS
Question 374Question →

A network administrator needs to deploy Link Aggregation (LAG) on a Cisco AireOS Wireless LAN Controller (WLC) connected to an upstream Cisco Catalyst switch. Place the operational steps required to enable and establish the LAG connection in the correct sequential order from first to last.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequential order to deploy LAG on an AireOS WLC is: 1) Enable LAG in WLC settings, 2) Save configuration and reboot the WLC, 3) Configure connected upstream switch ports into an EtherChannel using mode 'on', and 4) Verify operational status of the aggregated bundle.
To successfully deploy LAG on an AireOS Wireless LAN Controller, the feature must first be enabled in WLC global controller settings. Because enabling LAG reorganizes physical ports into a single logical interface, the configuration must be saved and the controller rebooted to take effect. Following the reboot, the upstream Catalyst switch physical ports must be configured into a single EtherChannel using mode 'on' (static aggregation, since AireOS does not negotiate via LACP or PAgP). Finally, the network engineer verifies that the Port-Channel is operational and passing traffic across mapped WLAN VLANs.

Step-by-Step Solution

1
Enable LAG feature on the WLC
The controller prepares the internal distribution system interfaces for multi-port bundling.
Global LAG setting must be changed prior to restarting the appliance.
2
Save configuration and restart WLC
The WLC reboots and binds all physical distribution ports into a single logical LAG interface.
AireOS hardware architecture requires a system reboot to apply LAG implementation across distribution ports.
3
Configure switch ports with static EtherChannel
The upstream Catalyst switch binds its corresponding interfaces into a single port-channel using mode 'on'.
AireOS WLCs do not support dynamic EtherChannel negotiation protocols like LACP or PAgP.
4
Verify port-channel operation and data flow
Operational status is confirmed and WLAN VLAN traffic flows across the unified bundle.
Ensures that all bundled interfaces forward traffic properly without port mismatches or STP blocking.

Key Concept

AireOS WLC Link Aggregation deployment workflow and static switch EtherChannel requirements.
Question 375Question →

A network engineer is configuring Rapid PVST+ on a Cisco Catalyst switch. The engineer needs to set the switch priority for VLAN 45 so that the total Bridge Identifier (BID) priority field transmitted in BPDUs equals 20525. Which global configuration command must the engineer execute on the switch?

Show answer & explanation

Answer: spanning-tree vlan 45 priority 20480

Answer

spanning-tree vlan 45 priority 20480
In Rapid PVST+, the Bridge Identifier (BID) priority field consists of a 4-bit bridge priority and a 12-bit System ID Extension (VLAN ID). Because 4 bits are allocated to the configurable priority, values must be multiples of 212=40962^{12} = 4096. To achieve a total priority of 20525 for VLAN 45, the base priority must be configured as 20525−45=2048020525 - 45 = 20480.

Step-by-Step Solution

1
Identify the System ID Extension value for the target VLAN.
The System ID Extension equals the VLAN ID, which is 45.
Rapid PVST+ encodes the VLAN number in the 12-bit System ID Extension portion of the Bridge Identifier (BID).
2
Calculate the required base bridge priority value.
20525−45=2048020525 - 45 = 20480
Total Bridge Priority = Base Priority + System ID Extension.
3
Verify that the base priority is a valid increment of 4096.
20480/4096=520480 / 4096 = 5 (exact integer multiplier)
Cisco Catalyst switches require bridge priority to be configured in increments of 4096.

Key Concept

Rapid PVST+ System ID Extension and Priority Calculation
Question 376Question →

A network administrator is reviewing the layer 2 topology operational characteristics on a Cisco Catalyst switch block running Rapid PVST+. Which two statements accurately describe the port roles and operational state transitions of Rapid PVST+?

Select all that apply

Show answer & explanation

Answer: An Alternate port receives BPDUs from neighboring switches and provides an alternate backup path toward the Root Bridge.; Rapid PVST+ streamlines protocol port states to Discarding, Learning, and Forwarding, eliminating the separate Disabled, Blocking, and Listening states used in 802.1D.

Answer

The two correct statements are that an Alternate port receives BPDUs from neighboring switches to act as a backup path to the Root Bridge, and that Rapid PVST+ simplifies port states into Discarding, Learning, and Forwarding.
Rapid PVST+ simplifies 802.1D port states into Discarding, Learning, and Forwarding while introducing the Alternate port role as a pre-calculated backup path to the Root Bridge that receives BPDUs from alternate neighboring switches.

Step-by-Step Solution

1
Analyze Rapid PVST+ port roles
Identify that an Alternate port offers a direct backup path to the Root Bridge via another switch, while a Backup port offers a redundant path on a shared segment from the same switch.
Rapid PVST+ explicitly defines Alternate and Backup port roles to facilitate immediate proposal/agreement convergence.
2
Analyze Rapid PVST+ port states
Confirm that Rapid PVST+ merges Disabled, Blocking, and Listening into the Discarding state.
RSTP (802.1w) optimized port state efficiency by maintaining only three operational states: Discarding, Learning, and Forwarding.
3
Evaluate invalid bridge priority and PortFast claims
Reject arbitrary bridge priorities (must use 4096 increments) and trunk PortFast configurations.
System ID extension enforces 4096 step increments, and PortFast on trunks removes loop protection.

Key Concept

Rapid PVST+ Port Roles and Port State Operations
Estimated Time:1m 30s
Question 377Question →

A network technician is configuring interface GigabitEthernet0/3 on a Cisco Catalyst switch to connect an end-user workstation to VLAN 25. Which TWO commands must be executed within interface configuration mode to properly set up this access port? (Select two.)

Select all that apply

Show answer & explanation

Answer: switchport mode access; switchport access vlan 25

Answer

To configure an interface as a static access port in VLAN 25, the engineer must enter interface configuration mode and execute both 'switchport mode access' and 'switchport access vlan 25'.
Configuring a host-facing access port requires setting the operational mode to static access using 'switchport mode access' and assigning the desired broadcast domain membership using 'switchport access vlan 25'. Both commands must be executed under interface configuration mode.

Step-by-Step Solution

1
Set the switchport mode to access
Interface is hardcoded to operate as an access port rather than negotiating a trunk connection.
Security and operational best practices require explicitly setting access mode on host-facing ports.
2
Associate the access port with VLAN 25
Traffic on the interface is assigned to broadcast domain VLAN 25.
The command 'switchport access vlan 25' binds the port membership to VLAN 25.

Key Concept

Cisco IOS Switch Access Port Configuration Commands
Question 378Question →

A Cisco Catalyst switch running Rapid PVST+ has a primary uplink on interface GigabitEthernet0/1 functioning as the Root Port for VLAN 10. Interface GigabitEthernet0/2 connects to a secondary distribution switch and functions as an Alternate Port for VLAN 10 in the Discarding state. If interface GigabitEthernet0/1 suddenly fails, how does Rapid PVST+ handle the state and role transition for interface GigabitEthernet0/2?

Show answer & explanation

Answer: Interface GigabitEthernet0/2 immediately transitions to the Root Port role and enters the Forwarding state.

Answer

Interface GigabitEthernet0/2 immediately transitions to the Root Port role and enters the Forwarding state.
Rapid PVST+ (based on IEEE 802.1w) incorporates built-in fast convergence features. An Alternate port is a backup path to the Root Bridge that receives BPDUs from a neighboring switch. When the current Root Port fails, the Alternate port can immediately assume the Root Port role and transition directly into the Forwarding state without waiting for legacy 802.1D forward delay timers.

Step-by-Step Solution

1
Identify the initial Rapid PVST+ port roles and states for VLAN 10.
GigabitEthernet0/1 is the active Root Port (Forwarding state), and GigabitEthernet0/2 is an Alternate Port (Discarding state).
The Alternate port receives superior BPDUs from another switch, serving as a standby path to the Root Bridge.
2
Analyze the impact of the primary uplink failure on GigabitEthernet0/1.
The switch loses its active path to the Root Bridge via GigabitEthernet0/1.
When the active Root Port fails, the switch must select the next best path to the Root Bridge.
3
Apply Rapid PVST+ (802.1w) fast convergence rules for Alternate ports.
GigabitEthernet0/2 immediately becomes the new Root Port and moves directly to the Forwarding state without passing through Listening or Learning states.
Rapid PVST+ integrates UplinkFast functionality into the protocol design, allowing pre-identified Alternate ports to transition to Forwarding instantly upon Root Port failure.

Key Concept

Rapid PVST+ Alternate Port Fast Transition Mechanics
Estimated Time:1m 0s
Question 379Question →

An infrastructure team is provisioning access layer switch interfaces for newly deployed Cisco Lightweight Access Points (LAPs) operating strictly in Local mode. All wireless client traffic will be encapsulated within CAPWAP tunnels back to the central Wireless LAN Controller (WLC). Which switch port configuration must be applied to the switch interfaces connecting directly to these Access Points?

Show answer & explanation

Answer: Configure each interface as a standard Layer 2 access port assigned to the AP management VLAN.

Answer

The switch interfaces must be configured as standard Layer 2 access ports assigned to the AP management VLAN.
Local mode APs send all wireless user traffic through CAPWAP tunnels to the Wireless LAN Controller. Because the AP itself only requires network access to obtain an IP address and reach the WLC IP, the switch interface connecting to the AP only needs to be configured as a standard access port in the AP management VLAN.

Step-by-Step Solution

1
Analyze the operational mode of the Access Points
The APs operate in Local mode.
Local mode APs do not switch wireless client traffic locally onto the access switch; instead, all data and control traffic are encapsulated into CAPWAP tunnels sent directly to the central WLC.
2
Determine the VLAN and switchport requirements for Local mode APs
The AP requires only an IP address in the AP management VLAN to establish its CAPWAP tunnel.
Because client VLAN tags are encapsulated within the CAPWAP data payload, the physical switch port connected to the AP does not need to trunk multiple client VLANs.
3
Select the appropriate switchport mode configuration
Set the switch port mode to access and assign it to the AP management VLAN.
An access port provides untagged Layer 2 connectivity for the AP to receive an IP address via DHCP and communicate with the WLC.

Key Concept

Local mode AP switchport requirements vs FlexConnect mode requirements
Question 380Question →

A network administrator is hardening switch port security on a Cisco Catalyst switch. Interface GigabitEthernet0/1 currently has default settings and is connected to a host workstation in the Accounting department. The administrator must explicitly configure the port to operate statically as an access interface in VLAN 30 (named ACCOUNTING) and ensure Dynamic Trunking Protocol (DTP) frames are no longer sent on this link. Which set of commands must be executed in interface configuration mode to fulfill these requirements?

Show answer & explanation

Answer: switchport mode access
switchport access vlan 30

Answer

Configuring 'switchport mode access' statically defines the interface as an access port and disables DTP negotiation, while 'switchport access vlan 30' assigns the port to VLAN 30.
The command 'switchport mode access' statically disables trunking negotiation (DTP) and forces the port into operational access mode. Combined with 'switchport access vlan 30', it correctly places untagged traffic from the workstation into VLAN 30.

Step-by-Step Solution

1
Set the administrative operational mode of GigabitEthernet0/1 to static access.
The interface is forced into access mode, stopping DTP frame generation and preventing unwanted trunk negotiation.
By default, Cisco switch ports operate in dynamic auto mode, which actively responds to DTP negotiation.
2
Assign the interface to the target VLAN using 'switchport access vlan 30'.
Untagged frames entering GigabitEthernet0/1 are assigned to VLAN 30.
Access ports must be explicitly assigned to their designated VLAN broadcast domain.

Key Concept

Static Access Port Assignment and DTP Disabling
Estimated Time:1m 15s
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