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Network Access

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Question 301Question →

A network administrator is optimizing a Cisco Catalyst switch that connects desktop computers and IP phones across access ports. The administrator enables Cisco STP PortFast on these access interfaces. Which two operational behaviors or benefits occur on a PortFast-enabled access interface when a device connects to it? (Select two.)

Select all that apply

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Answer: The interface transitions immediately from the Blocking state to the Forwarding state, bypassing the Listening and Learning states.; The switch suppresses Spanning Tree Topology Change Notification (TCN) messages when the interface state changes.

Answer

PortFast immediately transitions an access port to the Forwarding state by bypassing the Listening and Learning states, and it prevents the switch from issuing Topology Change Notifications (TCNs) when edge interfaces flap.
Enabling Cisco STP PortFast on edge ports provides two primary operational behaviors: first, it bypasses the 802.1D Listening and Learning states so the port enters the Forwarding state immediately upon link up. Second, it prevents the switch from generating Topology Change Notifications (TCNs) when the link toggles, protecting the network from frequent, unnecessary MAC table flushes.

Step-by-Step Solution

1
Analyze the function of STP PortFast on edge ports.
PortFast is intended for edge ports connected to end hosts, allowing immediate transition to Forwarding.
By skipping the 15-second Listening and 15-second Learning timer delays (30 seconds total convergence delay in 802.1D STP), end devices avoid DHCP and application initialization timeouts.
2
Evaluate the impact of PortFast on switch topology updates.
No TCN BPDUs are generated when a PortFast-enabled interface changes link state.
Link state changes on user workstations occur frequently and should not cause the rest of the network to flush MAC address tables.

Key Concept

STP PortFast Benefits and Operational Behavior
Question 302Question →

A network administrator needs to deploy a new corporate WLAN using WPA2/WPA3 Enterprise authentication on a Cisco AireOS Wireless LAN Controller (WLC) via the web GUI. Arrange the following administrative tasks in the correct sequential order required to successfully configure and activate the WLAN for wireless client connectivity.

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Answer

The correct procedural sequence is: 1) Navigate to WLANs > WLANs, select 'Create New' and enter the Profile Name and SSID; 2) On the General tab, map the dynamic interface; 3) Under Security > Layer 2, configure WPA2/WPA3 and 802.1X key management; 4) On the AAA Servers tab, bind the RADIUS authentication server; 5) Return to the General tab to check the Status (Enabled) box and click Apply.
Configuring a WLC WLAN requires a strict logical workflow: basic WLAN instantiation (SSID/Profile Name), interface assignment for VLAN traffic routing, Layer 2 security protocol selection (802.1X), external AAA RADIUS binding, and finally enabling the administrative Status to begin broadcasting the SSID.

Step-by-Step Solution

1
Initialize WLAN creation in WLC GUI
Defines the WLAN container with unique SSID and Profile Name.
Creating the basic WLAN structure is the mandatory starting point before detailed parameters can be edited.
2
Assign dynamic interface mapping
Associates wireless client traffic to the appropriate VLAN interface.
Setting the interface on the General tab ensures client packets are tagged with the correct VLAN ID upon join.
3
Define Layer 2 security mechanism
Sets authentication mode to 802.1X (WPA2/WPA3 Enterprise).
Configuring 802.1X key management under Security > Layer 2 specifies that external AAA authentication is required.
4
Map external RADIUS authentication server
Binds the globally defined RADIUS server to this specific WLAN under AAA Servers.
The WLC cannot authenticate 802.1X clients without associating a RADIUS server to the WLAN.
5
Enable WLAN status and apply changes
Activates the WLAN on member Access Points for client probing and association.
By default, new WLANs are disabled; enabling status must occur after all dependencies (interface, security, AAA) are configured.

Key Concept

WLC GUI WLAN Configuration Sequence
Question 303Question →

An enterprise network deployment incorporates a Cisco Wireless LAN Controller (WLC) connected via four physical distribution system ports to a Cisco Catalyst switch stack. The network engineer enables Link Aggregation (LAG) globally on the controller and reboots the device. On the switch stack, the engineer attempts to establish the EtherChannel by configuring `channel-group 1 mode active` across ports GigabitEthernet 1/0/1 through 1/0/4. Following the WLC reboot, the controller loses all network management connectivity, and the switch logs indicate that the port-channel interface is down due to a negotiation failure. Which switch configuration modification will restore network connectivity while maintaining LAG operational on the controller?

Show answer & explanation

Answer: Change the channel group negotiation mode on all participating switch interfaces to mode on.

Answer

Change the channel group negotiation mode on all participating switch interfaces to mode on.
When Link Aggregation (LAG) is enabled on a Cisco Wireless LAN Controller (running AireOS), the controller bundles all physical distribution system ports into a single operational interface. AireOS controllers do not support dynamic link negotiation protocols such as Link Aggregation Control Protocol (LACP) or Port Aggregation Protocol (PAgP). Therefore, the connected interfaces on the upstream Cisco Catalyst switch must be configured as a static EtherChannel using `channel-group <id> mode on`.

Step-by-Step Solution

1
Analyze the WLC Link Aggregation (LAG) signaling requirements.
Cisco AireOS Wireless LAN Controllers require static EtherChannel bundling without dynamic LACP or PAgP negotiation frames.
The controller firmware bundles all physical distribution system ports into a single non-negotiated logical port.
2
Identify the cause of the port-channel down state on the switch.
The switch was configured with `channel-group 1 mode active`, expecting LACP LACPDU negotiation packets that the WLC never sends.
Because LACP negotiation times out without receiving LACPDUs from the WLC, the switch keeps the port-channel in a suspended/down state.
3
Determine the necessary configuration change on the switch stack.
Change the interface configuration to `channel-group 1 mode on` across all attached switch ports.
Mode `on` forces the switch ports into a static EtherChannel bundle without waiting for negotiation frames.

Key Concept

WLAN Controller Link Aggregation (LAG) Switch Configuration Requirements
Question 304Question →

A network engineer is configuring network access for a newly installed Cisco Wireless LAN Controller (WLC) and Lightweight Access Points (APs). The WLC Management interface uses VLAN 10 to communicate with APs, while the Service Port is connected to a dedicated out-of-band management network. Which TWO statements accurately describe the operational requirements and characteristics of these management connections?

Select all that apply

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Answer: The Service Port operates strictly out-of-band for administrative access and cannot terminate CAPWAP tunnels from APs.; The switch port connected to the WLC Management interface must allow VLAN 10 traffic to pass CAPWAP control and data packets.

Answer

The Service Port provides out-of-band administrative management only and cannot terminate CAPWAP tunnels, while the switch port connected to the WLC Management interface must be configured to pass VLAN 10 traffic carrying CAPWAP control and data packets.
The correct options accurately identify the fundamental roles of Cisco WLC management access interfaces. The Service Port is dedicated to out-of-band administration and does not participate in CAPWAP data or control plane processing. The Management interface handles CAPWAP communication with APs, requiring the supporting switch interface to be configured with the appropriate VLAN access.

Step-by-Step Solution

1
Analyze WLC Service Port functionality
Identify that the Service Port is isolated for out-of-band management and does not carry CAPWAP tunnel traffic from APs.
Out-of-band ports are non-routable in-band interfaces designed solely for administrative access to the WLC CLI/GUI.
2
Analyze WLC Management Interface requirements
Verify that the switchport trunking or VLAN settings must explicitly allow VLAN 10 so APs can establish CAPWAP tunnels to the WLC Management IP address.
The WLC Management interface handles in-band management and CAPWAP tunnel termination for Lightweight APs.
3
Evaluate distractor statements regarding STP PortFast and AP Local mode
Reject the statements advocating PortFast on trunk links and local switching by Local mode APs via the Service Port.
PortFast on standard trunks risks Layer 2 loops, and AP local switching requires FlexConnect mode, not default Local mode.

Key Concept

WLC Management Interface vs. Service Port Roles and Switch Interfacing
Question 305Question →

A network administrator needs to configure a routed (Layer 3) EtherChannel bundle (Port-channel 10) on a Cisco switch using Link Aggregation Control Protocol (LACP) active mode across physical interfaces GigabitEthernet 0/1 and GigabitEthernet 0/2. What is the correct sequence of CLI steps to complete this configuration?

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Answer

The correct configuration order requires first selecting the physical member interfaces, disabling Layer 2 switching on them using 'no switchport', adding them to channel-group 10 with LACP active mode, navigating into interface Port-channel 10 mode, and finally ensuring Layer 3 operation with an IP address assigned to the logical interface.
To build a Layer 3 EtherChannel using LACP, an engineer must first select physical member ports, convert them into routed ports with 'no switchport', add them to the channel group using 'channel-group 10 mode active', navigate to the logical 'interface Port-channel 10', and assign the IP address to the logical port-channel interface.

Step-by-Step Solution

1
Select physical member links
Enters interface range configuration mode for GigabitEthernet 0/1 and 0/2.
Changes must be applied to both physical candidate interfaces simultaneously.
2
Disable switchport mode on member links
Converts physical member interfaces from Layer 2 switchports to Layer 3 routed interfaces.
A Layer 3 EtherChannel requires member interfaces to be configured with 'no switchport' prior to bundle creation.
3
Bind member interfaces to LACP channel group
Configures LACP active mode and creates logical interface Port-channel 10.
The 'mode active' keyword enables LACP active negotiation.
4
Select logical Port-channel interface
Enters interface configuration mode for interface Port-channel 10.
Global network addressing must be applied to the bundle interface, not physical member links.
5
Configure IP address on logical interface
Disables switchport mode on the logical port-channel (if needed) and assigns the IPv4 address.
IP addresses in a Layer 3 EtherChannel reside on the logical Port-channel interface itself.

Key Concept

Layer 3 LACP EtherChannel CLI configuration order
Estimated Time:1m 30s
Question 306Question →

A network engineer is configuring a dedicated voice wireless network for wireless IP phones using the Cisco Wireless LAN Controller (WLC) web GUI. To ensure optimal performance and security, the engineer must set the Quality of Service (QoS) profile to Platinum (Voice) and restrict direct traffic between wireless clients on the same WLAN by enabling Peer-to-Peer Blocking. Which combination of GUI tabs under WLANs > Edit must the engineer access to configure these two settings?

Show answer & explanation

Answer: Configure the QoS profile under the QoS tab, and configure Peer-to-Peer Blocking under the Advanced tab.

Answer

Configure the QoS profile under the QoS tab, and configure Peer-to-Peer Blocking under the Advanced tab.
In the Cisco AireOS WLC web interface, editing a WLAN presents several dedicated tabs: General, Security, QoS, Policy-Mapping, AAA Servers, DNS, Device Analytics, IPv6, Advanced, and FlexConnect. The QoS tab specifies the Quality of Service profile (Platinum, Gold, Silver, Bronze) applied to client traffic. The Advanced tab controls operational client behavior and features, including Peer-to-Peer Blocking (Disabled, Drop, or Upstream-Forward), AAA Override, Mandatory DHCP, and Client Exclusion.

Step-by-Step Solution

1
Identify the WLC GUI navigation path for Quality of Service (QoS) profile settings.
In the Cisco WLC web GUI, navigate to WLANs > WLANs > Edit '[WLAN Name]' and select the QoS tab to choose the Quality of Service profile (Platinum/Voice).
QoS profiles determine packet marking and prioritization policies for wireless traffic and are located on the dedicated QoS tab.
2
Identify the WLC GUI navigation path for Peer-to-Peer (P2P) Blocking configuration.
Under WLANs > WLANs > Edit '[WLAN Name]', select the Advanced tab and locate the Peer-to-Peer Blocking Action drop-down menu.
Peer-to-Peer Blocking prevents client-to-client communication within the same WLAN and is categorized under operational WLAN behavior on the Advanced tab.

Key Concept

Cisco WLC GUI WLAN Configuration Tabs and Parameter Mapping
Question 307Question →

A network engineer is configuring Layer 2 neighbor discovery on a Cisco Catalyst switch connected to both Cisco switches and third-party network endpoints. Which two statements correctly describe the operational characteristics and default behaviors of Cisco Discovery Protocol (CDP) and Link Layer Discovery Protocol (LLDP)? (Choose two.)

Select all that apply

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Answer: CDP is a Cisco proprietary protocol enabled by default with a 60-second update timer, whereas LLDP is an IEEE 802.1AB standard that uses a 30-second update timer by default.; Both CDP and LLDP use Type-Length-Value (TLV) structures within Layer 2 frames to convey neighbor information such as device capabilities, port identifiers, and management addresses.

Answer

CDP is a Cisco proprietary protocol enabled by default with a 60-second update timer, whereas LLDP is an IEEE 802.1AB standard that uses a 30-second update timer by default; both CDP and LLDP use Type-Length-Value (TLV) structures within Layer 2 frames to convey neighbor information.
CDP is a Cisco proprietary protocol operating with a 60-second update timer and 180-second holdtime, whereas LLDP is an open standard defined by IEEE 802.1AB that operates with a 30-second update timer and 120-second holdtime. Both protocols organize neighbor information using Type-Length-Value (TLV) structures within Layer 2 frames.

Step-by-Step Solution

1
Identify default protocol parameters and standards for CDP and LLDP.
CDP is Cisco proprietary (default 60-second update, 180-second holdtime), while LLDP is defined by IEEE 802.1AB (default 30-second update, 120-second holdtime).
Distinguishing between proprietary and open standards along with their default timer values is essential for multi-vendor network administration.
2
Analyze frame structure and data encoding methods.
Both protocols encapsulate neighbor metadata into modular Type-Length-Value (TLV) elements transmitted inside Data Link layer frames.
TLVs allow flexible exchange of system attributes, management IP addresses, and port descriptions across Layer 2 neighbors.
3
Evaluate protocol reaction to native VLAN configuration errors.
Layer 2 discovery protocols report mismatches using log messages but do not alter port forwarding states or block traffic.
Traffic suppression due to misconfiguration is handled by Spanning Tree Protocol (STP) mechanisms, not CDP or LLDP.

Key Concept

Layer 2 Discovery Protocols (CDP and LLDP) standards, default timers, and TLV structure
Question 308Question →

A network operations team configures the command `spanning-tree portfast` on access interface GigabitEthernet0/1 of a Cisco Catalyst switch. Which statement accurately describes the operational behavior of this interface when a link-up event occurs?

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Answer: The interface immediately transitions to the STP Forwarding state, bypassing the Listening and Learning states.

Answer

The interface immediately transitions to the STP Forwarding state, bypassing the Listening and Learning states.
The correct answer states that the interface immediately transitions to the STP Forwarding state, bypassing the Listening and Learning states. This eliminates the standard 30-second STP timer delay (15 seconds Listening + 15 seconds Learning) when connecting end-user edge devices, allowing protocols like DHCP to succeed immediately upon physical link link-up.

Step-by-Step Solution

1
Analyze standard 802.1D STP port state timers.
In traditional 802.1D STP, an interface transitions through Blocking → Listening (15s) → Learning (15s) → Forwarding, creating a total 30-second delay before traffic can be forwarded.
Understanding the baseline STP state progression highlights why end hosts experience initialization delays (such as DHCP timeouts).
2
Evaluate the specific function of Cisco STP PortFast.
PortFast allows edge ports connected directly to single workstations or servers to bypass the Listening and Learning states and enter Forwarding instantly.
End-user hosts do not create switching loops, so delaying their port activation serves no loop prevention purpose.
3
Confirm STP safeguards on PortFast interfaces.
STP is still active on the port and will send BPDUs. If another switch is plugged into a PortFast port, receipt of BPDUs or BPDU guard will protect the topology.
PortFast optimizes state transition speed without completely disabling Spanning Tree monitoring.

Key Concept

Cisco PortFast State Bypass and Operational Mechanics
Estimated Time:1m 0s
Question 309Question →

A network administrator is preparing to bundle the physical distribution system ports on a Cisco Wireless LAN Controller (WLC) to increase bandwidth and redundancy toward an upstream Cisco Catalyst switch stack. Which two requirements or operational characteristics apply when Link Aggregation (LAG) is enabled on the Cisco WLC?

Select all that apply

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Answer: The connected ports on the upstream switch must be combined into a single static EtherChannel bundle using the manual mode 'on'.; Enabling LAG merges all physical distribution system ports into a single logical interface, preventing the creation of multiple separate EtherChannel groups on the controller.

Answer

The correct options are that the upstream switch ports must be configured into a static EtherChannel using mode 'on', and that enabling LAG merges all physical distribution system ports into a single logical interface on the controller.
Enabling LAG on a Cisco Wireless LAN Controller consolidates all physical distribution ports into a single logical EtherChannel. Because the controller does not use dynamic EtherChannel negotiation protocols like LACP or PAgP, the connected upstream switch ports must be manually configured in static EtherChannel mode using the 'channel-group <id> mode on' command.

Step-by-Step Solution

1
Analyze Cisco WLC EtherChannel / LAG negotiation protocol requirements.
Cisco WLC LAG requires static frame distribution without LACP or PAgP signaling.
The WLC does not run LACP or PAgP daemons on its physical ports, requiring the connected switch ports to be set to static EtherChannel ('mode on').
2
Determine how physical ports are grouped when LAG is enabled on the controller.
All physical distribution system ports form one single logical bundle.
On a Cisco WLC, LAG is a global setting that combines all distribution ports into one single logical link bundle; multiple separate EtherChannel groups cannot be defined.
3
Evaluate AP behavior in Local mode vs FlexConnect mode upon WLC link bundle loss.
Local mode APs cease forwarding client traffic because they cannot switch traffic locally.
Local mode APs encapsulate all user data inside CAPWAP tunnels to the WLC. Local switching requires FlexConnect mode.

Key Concept

Cisco WLC Link Aggregation (LAG) Architecture and Trunking Requirements
Question 310Question →

Four Cisco Catalyst switches (SW1, SW2, SW3, and SW4) are deployed in an enterprise network running Rapid PVST+ for VLAN 10. SW1 is elected as the Root Bridge. SW4 connects to SW2 via interface GigabitEthernet0/1 and to SW3 via interface GigabitEthernet0/2. Both paths yield an identical cumulative root path cost of 4. SW2 has a lower Bridge ID than SW3. In addition, interfaces GigabitEthernet0/3 and GigabitEthernet0/4 on SW4 are both connected to the same unmanaged hub on a single shared collision domain. Which two statements correctly describe the Rapid PVST+ port roles and state operations on SW4 for VLAN 10? (Select two.)

Select all that apply

Show answer & explanation

Answer: GigabitEthernet0/2 is assigned the Alternate port role and operates in the Discarding state.; GigabitEthernet0/4 is assigned the Backup port role and operates in the Discarding state.

Answer

The correct statements are that GigabitEthernet0/2 is assigned the Alternate port role operating in the Discarding state, and GigabitEthernet0/4 is assigned the Backup port role operating in the Discarding state.
In Rapid PVST+ (802.1w), port roles are defined based on path location and the source of BPDUs. GigabitEthernet0/1 is the Root Port because SW2 has a lower Bridge ID than SW3. GigabitEthernet0/2 receives BPDUs from another switch (SW3) offering a secondary root path, making it an Alternate port operating in the Discarding state. For GigabitEthernet0/3 and GigabitEthernet0/4 connected to the same hub, SW4 receives its own BPDUs; the port with the higher Port ID (GigabitEthernet0/4) becomes a Backup port operating in the Discarding state.

Step-by-Step Solution

1
Determine Root Port on SW4
GigabitEthernet0/1 selected as Root Port
Both SW2 and SW3 offer an equal root path cost of 4. The tie-breaker evaluates the neighbor Bridge ID. Because SW2 has a lower Bridge ID than SW3, the path through SW2 (GigabitEthernet0/1) is chosen as the Root Port.
2
Determine role for non-root path to another switch (GigabitEthernet0/2)
GigabitEthernet0/2 becomes an Alternate Port in Discarding state
An interface that receives BPDUs offering an alternate path to the Root Bridge from a neighboring switch acts as an Alternate port. In Rapid PVST+, Alternate ports are placed in the Discarding state.
3
Determine roles for interfaces connected to the shared hub (GigabitEthernet0/3 and GigabitEthernet0/4)
GigabitEthernet0/3 becomes Designated; GigabitEthernet0/4 becomes Backup in Discarding state
When multiple interfaces on the same switch connect to the same collision domain/hub, the switch receives its own BPDUs. The interface with the lower Port ID (GigabitEthernet0/3) becomes Designated, while the higher Port ID (GigabitEthernet0/4) takes the Backup port role in the Discarding state.

Key Concept

Rapid PVST+ Port Roles (Root, Designated, Alternate, Backup) and States (Discarding, Learning, Forwarding)
Question 311Question →

A network administrator is connecting two Cisco Catalyst switches using two physical Gigabit Ethernet links. On Switch-1, the physical interfaces are assigned using the command `channel-group 12 mode active`. On Switch-2, the corresponding physical interfaces are assigned using `channel-group 21 mode passive`. All physical interface speed, duplex, and VLAN settings match on both ends. What is the operational status of this EtherChannel bundle?

Show answer & explanation

Answer: The EtherChannel bundle forms successfully because channel group numbers are locally significant, and active-to-passive LACP modes successfully negotiate.

Answer

The EtherChannel bundle forms successfully because channel group numbers are locally significant, and active-to-passive LACP modes successfully negotiate.
The channel group number specified in the `channel-group <number> mode <mode>` command is strictly locally significant to the local Cisco switch. It identifies which logical Port-channel interface (e.g., Port-channel 12 vs Port-channel 21) member ports belong to locally. Furthermore, LACP negotiation succeeds when one switch is in `active` mode (initiating LACP packets) and the peer switch is in `passive` mode (responding to LACP packets).

Step-by-Step Solution

1
Evaluate channel group number significance across switch boundaries.
Channel group numbers (e.g., 12 on Switch-1 and 21 on Switch-2) define the local Port-channel interface ID on each individual switch and are not exchanged in LACP Data Units (LACPDUs).
Channel group numbers are strictly locally significant.
2
Evaluate LACP negotiation modes between Switch-1 and Switch-2.
Switch-1 is set to 'active' (actively initiates LACP negotiation) and Switch-2 is set to 'passive' (listens and responds to incoming LACP packets).
An active-to-passive combination satisfies LACP negotiation requirements.
3
Determine final EtherChannel bundle state.
Because physical parameters match and LACP negotiation succeeds, the Port-channel forms and transitions to an operational bundled state.
No configuration parameters block EtherChannel formation.

Key Concept

LACP Mode Negotiation and Channel Group Local Significance
Question 312Question →

A Cisco switch running Rapid PVST+ receives BPDUs across multiple candidate paths leading toward the Root Bridge. Place the tie-breaking criteria evaluated by the switch to elect its Root Port in the correct sequential order from first (1st) to last (4th).

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Answer

The correct sequence for Rapid PVST+ Root Port election is: 1) Lowest cumulative Root Path Cost, 2) Lowest sender Bridge ID, 3) Lowest sender Port ID, and 4) Lowest local (receiver) Port ID.
Rapid PVST+ follows a strict four-step decision tree to select a single Root Port on a non-root switch: 1) Lowest cumulative Root Path Cost, 2) Lowest sender Bridge ID (BID), 3) Lowest sender Port ID, and 4) Lowest local (receiver) Port ID.

Step-by-Step Solution

1
Evaluate incoming BPDU path cost values
Identify the link offering the lowest cumulative Root Path Cost to the Root Bridge
Rapid PVST+ prioritizes overall network topology bandwidth and cost over local port attributes.
2
Evaluate upstream switch Bridge IDs if path costs are equal
Select the neighbor switch that has the lowest BID value (Priority + System ID Extension + MAC Address)
When path costs match, preference is given to paths traversing higher-priority upstream bridges.
3
Evaluate sender Port IDs if BIDs are equal
Select the interface connected to the upstream neighbor port with the lowest Port ID
Multiple parallel links to the same upstream neighbor share identical Root Path Costs and sender BIDs.
4
Evaluate local receiver Port IDs if sender Port IDs are identical
Select the local receiving interface with the lowest Port ID
Serves as the final deterministic tie-breaker when connecting through an unmanaged hub or shared medium.

Key Concept

Rapid PVST+ Root Port Selection Tie-Breaker Order
Estimated Time:1m 15s
Question 313Question →

During a network maintenance audit on a Cisco Catalyst switch running legacy IEEE 802.1D Spanning Tree Protocol (STP), an engineer observes an access port bringing up a new link without Cisco PortFast configured. Place the standard 802.1D STP port states in chronological sequence, starting from the moment physical link protocol comes UP until full Layer 2 data frame transmission begins.

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Answer

The correct chronological sequence of 802.1D STP port states from link initialization to full frame transmission is Blocking state, Listening state, Learning state, and Forwarding state.
Under standard IEEE 802.1D STP operation without PortFast, an access interface experiences a total convergence delay of 30 seconds across standard state transitions. The interface moves sequentially through Blocking (loop detection), Listening (path calculation/BPDU processing for 15 seconds), Learning (MAC address table population for 15 seconds), and finally Forwarding (active user frame transmission).

Step-by-Step Solution

1
Identify the initial state immediately after physical link protocol initialization.
The port initializes in the Blocking state.
Under IEEE 802.1D, non-PortFast ports enter Blocking to evaluate potential Layer 2 topology loops by listening for BPDUs.
2
Determine the state transition following loop evaluation.
The port transitions to the Listening state.
In Listening state, the interface actively sends and receives BPDUs to elect Root Bridges and establish port roles without populating MAC tables or forwarding user traffic.
3
Identify the state transition after the first Forward Delay timer (15 seconds) expires.
The port enters the Learning state.
In Learning state, the switch begins learning source MAC addresses from received frames to populate its MAC table, but still drops user data frames.
4
Determine the final state transition after the second Forward Delay timer (15 seconds) expires.
The port reaches the Forwarding state.
With convergence established and MAC tables populated, the interface transitions to Forwarding to send and receive Layer 2 user data traffic.

Key Concept

802.1D Spanning Tree Protocol Port State Transition Sequence
Question 314Question →

An enterprise network uses Rapid PVST+ for spanning tree management across four Catalyst switches (SW-A, SW-B, SW-C, and SW-D) servicing VLAN 25. The bridge priorities for VLAN 25 are configured as follows:
- SW-A: priority 4096
- SW-B: priority 8192
- SW-C: priority 16384
- SW-D: priority 32768

SW-C has two direct 1 Gbps links (STP cost 4) connected to SW-B: interface Gi0/1 connects to SW-B interface Gi0/1, and interface Gi0/2 connects to SW-B interface Gi0/2. SW-C also has a direct 10 Gbps link (STP cost 2) on interface Gi0/3 connected directly to SW-A. SW-B connects directly to SW-A via a 1 Gbps link on interface Gi0/24.

If all switch MAC addresses follow standard numbering based on their switch letter (e.g., SW-A has the lowest MAC address) and default port priorities (128) are used throughout, which port role and state will interface Gi0/1 on SW-C adopt for VLAN 25?

Show answer & explanation

Answer: Alternate port in the Discarding state

Answer

Interface Gi0/1 on SW-C assumes the Alternate port role in the Discarding state.
In Rapid PVST+, SW-A is elected Root Bridge because it has the lowest Bridge ID (4096+25=41214096 + 25 = 4121). SW-C compares its path costs to SW-A: interface Gi0/3 has a 10 Gbps link (STP cost 2), giving a total cost of 2 to reach the Root Bridge. Interfaces Gi0/1 and Gi0/2 connect to SW-B (cost 4 to SW-B + cost 4 from SW-B to SW-A = total cost 8). Therefore, Gi0/3 is elected as SW-C's Root Port. On the links between SW-B and SW-C, SW-B is the Designated bridge because it advertises a lower Root Path Cost (4) than SW-C's path cost via SW-B. As a result, SW-C places its non-root interfaces connected to SW-B (Gi0/1 and Gi0/2) into the Alternate port role in the Discarding state.

Step-by-Step Solution

1
Determine the Root Bridge for VLAN 25.
SW-A has the lowest Bridge ID (4096+25=41214096 + 25 = 4121) and is elected as the Root Bridge.
STP elects the switch with the lowest Bridge ID (Priority + System ID Extension + MAC Address) as Root Bridge.
2
Calculate cumulative path costs from SW-C to Root Bridge (SW-A) to elect the Root Port.
Path via Gi0/3 (10 Gbps) has a cost of 22. Path via Gi0/1 or Gi0/2 through SW-B has a cost of 4 (SW-C to SW-B)+4 (SW-B to SW-A)=84 \text{ (SW-C to SW-B)} + 4 \text{ (SW-B to SW-A)} = 8. SW-C selects Gi0/3 as its Root Port in the Forwarding state.
The non-root bridge selects the interface with the lowest cumulative cost to the Root Bridge as its Root Port.
3
Determine Designated Bridge selection between SW-B and SW-C for the links on Gi0/1 and Gi0/2.
SW-B's Root Path Cost is 44 and Bridge ID is 82178217, whereas SW-C's Root Path Cost on those links would be higher. Additionally, SW-B has a superior Bridge ID (8217<164098217 < 16409). SW-B becomes the Designated switch for both links.
On each segment, the switch advertising the lowest Root Path Cost (or lowest Bridge ID as a tie-breaker) becomes the Designated Bridge.
4
Assign the port role and state to interface Gi0/1 on SW-C.
Because SW-C receives superior BPDUs on Gi0/1 from SW-B and the port is not its Root Port, Gi0/1 is designated as an Alternate port and placed in the Discarding state.
In Rapid PVST+, non-root ports that receive superior BPDUs from another switch are designated as Alternate ports and held in the Discarding state to prevent loops.

Key Concept

Rapid PVST+ Port Role and State Elections in Multi-Switch Topologies
Question 315Question →

A network engineer is establishing an EtherChannel bundle between two Cisco Catalyst switches using the Link Aggregation Control Protocol (LACP). Which two mode combinations across the opposing switches will result in a successfully negotiated EtherChannel? (Select two.)

Select all that apply

Show answer & explanation

Answer: Configuring 'channel-group 5 mode active' on the first switch and 'channel-group 5 mode passive' on the second switch; Configuring 'channel-group 5 mode active' on both switches

Answer

The correct answers are configuring active mode on one switch and passive mode on the other switch, and configuring active mode on both switches.
LACP requires at least one switch interface to actively initiate LACP protocol negotiations. The combination of active mode on both switches and the combination of active mode on one switch with passive mode on the opposing switch both satisfy this requirement, allowing the LACP negotiation handshake to complete successfully.

Step-by-Step Solution

1
Identify the aggregation protocol requested in the scenario.
The scenario explicitly specifies Link Aggregation Control Protocol (LACP), an IEEE 802.3ad open standard.
LACP supports only 'active' and 'passive' negotiation modes (or 'on' for unconditional bundling without LACP packets).
2
Analyze how LACP active and passive modes interact.
Active mode transmits LACP control frames proactively. Passive mode listent silently and responds only upon receiving LACP control frames.
At least one side of the connection must be set to active mode to initiate the protocol handshake.
3
Evaluate the provided configuration options against negotiation rules.
Active-to-passive and active-to-active combinations succeed. Passive-to-passive fails due to lack of initiation. Active-to-desirable fails due to mixing LACP with Cisco proprietary PAgP.
Matching compatible protocol negotiation settings is mandatory for EtherChannel establishment.

Key Concept

LACP EtherChannel Mode Negotiation Rules
Question 316Question →

A network administrator is tasked with configuring a new WPA2-Personal (PSK) wireless network for client connectivity using the Cisco Wireless LAN Controller (WLC) web GUI. Place the steps in the correct order to complete the WLAN deployment from initial creation to saving the final configuration.

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Answer

The correct procedural order is: 1) Navigate to WLANs and select Create New, 2) Define Profile Name, SSID, and WLAN ID, 3) Select the Interface/Interface Group and enable Status on the General tab, 4) Configure WPA2-PSK parameters under Security > Layer 2, 5) Enter the PSK passphrase, click Apply, and click Save Configuration.
Configuring a client-facing WLAN on a Cisco AireOS WLC follows a strict sequential process: First, initiate creation under the WLANs menu using Create New. Second, define basic network parameters (Profile Name, SSID, ID) and click Apply to launch the edit view. Third, select the client traffic Interface and check Enabled on the General tab. Fourth, navigate to Security > Layer 2 to specify WPA2 Policy and PSK authentication. Finally, enter the pre-shared key passphrase, click Apply to update running memory, and save the WLC configuration.

Step-by-Step Solution

1
Initiate WLAN creation
Accesses the preliminary WLAN creation setup window.
You must navigate to WLANs > Create New to start defining a new wireless network.
2
Set WLAN identifiers
Generates the new WLAN instance and opens the full configuration tabs.
The WLC requires a Profile Name, broadcast SSID, and numerical ID before generating the specific WLAN configuration page.
3
Map network interface and enable WLAN
Binds client traffic to the appropriate VLAN interface and sets the administrative state.
Under the General tab, mapping the interface connects clients to the intended subnet, and checking Enabled activates the SSID.
4
Configure Layer 2 WPA2-PSK security parameters
Sets the authentication method to pre-shared key under Layer 2 settings.
WPA2-Personal settings are located specifically under Security > Layer 2 tab > WPA+WPA2 > Auth Key Management > PSK.
5
Enter passphrase, apply configuration, and save state
Commits changes to active memory and saves NVRAM configuration.
Entering the PSK passphrase completes security settings; clicking Apply commits settings to the running configuration, and Save Configuration persists it across reboots.

Key Concept

WLC GUI WLAN Creation and Client Connectivity Workflow
Estimated Time:1m 30s
Question 317Question →

An enterprise network administrator is resolving network initialization delays for workstations connected to access ports on a Cisco Catalyst switch. The administrator decides to configure Cisco PortFast on these access interfaces. How does enabling PortFast alter the IEEE 802.1D Spanning Tree Protocol (STP) port state transition behavior upon link up?

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Answer: The interface bypasses the Listening and Learning states, transitioning immediately into the Forwarding state.

Answer

Enabling PortFast on an access interface causes it to bypass the standard 802.1D Listening and Learning states, transitioning immediately into the Forwarding state upon link activation.
Enabling PortFast on a Cisco switch access port allows the interface connected to an end device to bypass the 802.1D Listening (15s) and Learning (15s) states, transitioning immediately to the Forwarding state upon link activation. This eliminates initialization delays that cause host DHCP request timeouts.

Step-by-Step Solution

1
Analyze standard IEEE 802.1D Spanning Tree Protocol port convergence timers.
Standard 802.1D requires an access port to spend 15 seconds in the Listening state and 15 seconds in the Learning state (totaling 30 seconds) before reaching Forwarding.
These delays prevent transient bridging loops while the switch learns MAC addresses and listens for BPDUs.
2
Determine the impact of Cisco PortFast when configured on edge access ports connected to single end-user hosts.
The port skips Listening and Learning, moving directly to Forwarding upon link up.
Since end-user workstations do not initiate bridging loops, skipping intermediate timers prevents DHCP timeouts and initialization delays.

Key Concept

STP Port States and PortFast Benefits
Question 318Question →

A network engineer is implementing Link Aggregation (LAG) using IEEE 802.3ad LACP between a Cisco Catalyst 9800 Series Wireless Controller and an upstream Cisco Catalyst 9300 switch stack. Place the following implementation and verification steps in the correct chronological order required to establish the infrastructure link.

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Answer

The correct implementation sequence begins with configuring the physical switch interfaces with LACP mode active, configuring trunking parameters on the resulting switch Port-channel interface, configuring the WLC uplink EtherChannel bundle, verifying Layer 2 bundle operation with 'show etherchannel summary', and finally validating WLC management reachability and CAPWAP tunnel stability.
Establishing a Link Aggregation connection between a Cisco Catalyst 9800 WLC and an upstream switch requires a structured bottom-up approach. First, physical switch ports must be assigned to the LACP channel group ('channel-group 10 mode active'). Second, the resulting logical Port-channel interface must be configured with 802.1Q trunking and VLAN parameters. Third, the controller-side interfaces must be bundled into the corresponding uplink EtherChannel. Fourth, the engineer must verify Layer 2 LACP negotiation using 'show etherchannel summary' to ensure the channel state is 'SU' and member interfaces display 'P'. Finally, end-to-end control plane operation is verified by testing WLC management reachability and AP CAPWAP tunnel stability.

Step-by-Step Solution

1
Define switch member ports
Physical switch ports are associated into channel-group 10 using active LACP negotiation.
Assigning physical member ports creates the logical Port-channel interface on the switch.
2
Configure switch Port-channel interface
The Port-channel interface is set to switchport mode trunk with designated native and allowed VLANs.
Applying trunk configuration to the logical Port-channel ensures consistent trunking behavior across all bundled physical member links.
3
Configure WLC uplink LAG bundle
Controller physical ports are grouped into an uplink EtherChannel bundle.
With the switch ready to negotiate, the controller side is enabled for link aggregation.
4
Verify EtherChannel protocol status
Switch CLI displays 'SU' (Layer 2, In-use) for Port-channel 10 and 'P' (Bundled) for all member ports.
Verifying LACP status ensures physical links negotiated properly without misconfigurations such as mode mismatches or suspended ports.
5
Verify network access and CAPWAP operation
Management traffic reaches the WLC IP and AP CAPWAP tunnels operate successfully over the aggregated link.
End-to-end verification validates overall infrastructure connectivity and wireless control plane operation.

Key Concept

WLAN Infrastructure LAG and Switch EtherChannel Implementation Sequence
Estimated Time:2m 0s
Question 319Question →

An administrator is configuring a wireless network using the Cisco Wireless LAN Controller (WLC) web interface. The WLAN profile has been created and mapped to the proper client interface, but wireless clients are unable to automatically detect the network name during passive scanning. However, clients can connect successfully when the network name is entered manually. Which configuration setting under the WLANs > Edit 'General' tab must be selected to resolve this issue?

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Answer: Broadcast SSID

Answer

Broadcast SSID
Enabling the Broadcast SSID check box under the WLAN General tab causes the WLC to instruct APs to include the network name (SSID) in 802.11 beacon management frames. This allows client devices performing passive scans to discover and display the wireless network in their list of available networks.

Step-by-Step Solution

1
Identify the symptom described in the scenario.
Clients cannot detect the wireless network via passive scanning, but can connect if the SSID is configured manually.
This indicates that beacon frames sent by the Access Point are hiding the SSID parameter.
2
Locate the appropriate setting in the WLC GUI.
Navigate to WLANs > Edit for the specified WLAN profile, under the General tab.
Basic WLAN parameters like SSID name, profile name, global status, and broadcast settings are located on the General tab.
3
Select the setting that enables SSID advertisement in beacon frames.
Check the Broadcast SSID check box.
Enabling Broadcast SSID ensures the network name is transmitted in beacon frames for client discovery.

Key Concept

WLC GUI WLAN General Tab Configuration
Question 320Question →

A network administrator is configuring access interfaces on a Cisco Catalyst switch connected directly to workstations. To prevent DHCP address negotiation timeouts caused by Spanning Tree Protocol (STP) initialization delays, the administrator applies the `spanning-tree portfast` command. Which two operational traits accurately describe the behavior of an interface configured with PortFast? (Select two.)

Select all that apply

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Answer: The interface bypasses the Listening and Learning states, transitioning immediately to the Forwarding state upon link activation.; The switch suppresses Topology Change Notifications (TCNs) for the interface when its link state toggles.

Answer

Enabling PortFast on an access interface causes it to immediately transition to the STP Forwarding state (bypassing Listening and Learning states) and suppresses Topology Change Notifications (TCNs) when the link status changes.
PortFast provides two primary operational advantages on edge interfaces: it skips the 802.1D Listening and Learning states to enter Forwarding instantly upon link activation, and it suppresses Topology Change Notifications (TCNs) when host connectivity toggles.

Step-by-Step Solution

1
Analyze standard 802.1D STP convergence delays.
Standard 802.1D transitions through Blocking -> Listening (15s) -> Learning (15s) -> Forwarding, taking 30 seconds total before data forwarding begins.
This delay causes end-user devices (like workstations seeking DHCP leases) to experience timeouts before the port reaches Forwarding state.
2
Identify the state transition behavior of PortFast.
PortFast places the access interface immediately into the Forwarding state upon link up, bypassing Listening and Learning.
Edge ports connected to single host devices cannot create Layer 2 loops upon initialization.
3
Identify the topology notification impact of PortFast.
Link state changes on PortFast ports do not trigger Topology Change Notifications (TCNs).
Edge end-user devices turning on or off do not change the core Layer 2 forwarding topology, avoiding unnecessary clearing of switch MAC address tables.

Key Concept

STP PortFast operational behavior and TCN suppression on access ports
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