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Network Access

400 questions

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Question 81Question →

A network administrator needs to perform initial configuration and out-of-band management on a newly deployed Cisco Wireless LAN Controller (WLC). Which WLC interface is specifically dedicated to out-of-band management and network recovery, operating completely isolated from the data traffic processing plane?

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Answer: Service Port

Answer

The Service Port is the dedicated physical interface reserved for out-of-band management, system restoration, and initial setup on a Cisco WLC.
The Service Port is a dedicated physical port on Cisco Wireless LAN Controllers that provides isolated, out-of-band management capabilities. It operates on its own discrete subnet and interface, allowing administrators to access the controller for initial setup, troubleshooting, or recovery even when the main network links or distribution switches are offline.

Step-by-Step Solution

1
Identify out-of-band management requirements for Cisco WLC architectures.
Recognize that out-of-band traffic must be physically segregated from the in-band data paths and distribution switch ports.
Out-of-band access ensures administrative connectivity remains operational even during network outages affecting main data VLANs.
2
Differentiate between WLC interfaces based on their functional roles.
The Service Port handles out-of-band management, the Management Interface handles in-band management and CAPWAP control, Virtual Interface handles web auth/DHCP relay, and Dynamic Interfaces handle WLAN client traffic.
Cisco controllers separate administrative control planes across distinct physical and logical interfaces.

Key Concept

Cisco WLC Physical and Logical Interface Roles
Question 82Question →

Place the tie-breaking criteria evaluated by a non-root switch running Rapid PVST+ in the correct sequence (from first evaluated to last evaluated) when selecting its Root Port.

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Answer

The correct sequence for Rapid PVST+ Root Port selection tie-breaking is: 1) Lowest cumulative Root Path Cost, 2) Lowest Designated (Sender) Bridge ID, 3) Lowest Designated (Sender) Port ID, and 4) Lowest Local Port ID on the receiving switch.
Rapid PVST+ evaluates Root Port selection strictly in sequence: cumulative path cost first, followed by upstream sender Bridge ID, upstream sender Port ID, and finally the local receiving Port ID as a last resort.

Step-by-Step Solution

1
Identify the primary criterion for Root Port selection in Spanning Tree operations.
Path cost evaluation is performed first.
The switch determines the shortest administrative distance to the Root Bridge by adding the local port cost to the root path cost reported in the incoming BPDU.
2
Evaluate the first tie-breaker if path costs are equal.
Designated (Sender) Bridge ID is evaluated.
When equal-cost paths originate from different neighboring switches, the switch prefers the neighbor with the lowest Bridge ID (Priority + System ID Extension + MAC Address).
3
Evaluate the second tie-breaker if receiving BPDUs from the same neighbor across parallel links.
Designated (Sender) Port ID is evaluated.
When parallel links connect to the same upstream switch, the neighbor Bridge ID is identical, so the sender's Port ID (Port Priority + Port Number) breaks the tie.
4
Evaluate the final tie-breaker if BPDUs arrive on different local interfaces from the exact same remote port.
Local Port ID is evaluated.
If all sender parameters are identical, the local receiving switch uses its own lowest Port ID (Port Priority + Port Number) as the definitive tie-breaker.

Key Concept

Rapid PVST+ Root Port Selection Algorithm
Question 83Question →

Match each Cisco Wireless LAN Controller (WLC) interface type to its corresponding primary function.

Click a left item, then click its matching right item

Items

Management Interface
Service Port
Virtual Interface
Dynamic Interface

Matches

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Answer

Management Interface matches in-band access and CAPWAP termination; Service Port matches out-of-band recovery management; Virtual Interface matches mobility management, DHCP relay, and web auth; Dynamic Interface matches user VLAN data mapping.
Each WLC interface has a distinct architectural purpose: the Management Interface is responsible for in-band administration and CAPWAP tunnel termination; the Service Port is isolated for out-of-band maintenance; the Virtual Interface facilitates client web auth and DHCP relaying; and Dynamic Interfaces handle user data mapping to trunked VLANs.

Step-by-Step Solution

1
Identify in-band management and CAPWAP termination requirements
The Management Interface handles in-band administrative traffic and CAPWAP communications with APs.
Lightweight Access Points terminate CAPWAP control and data tunnels on the WLC management interface.
2
Identify out-of-band administrative access requirements
The Service Port provides dedicated, isolated out-of-band access.
The service port is non-routable and independent of the main data path for out-of-band management and recovery.
3
Differentiate between Virtual and Dynamic internal interfaces
Virtual interface manages web auth/DHCP relaying, while Dynamic interfaces bind WLANs to user VLANs.
Virtual interface provides internal Layer 3 services to clients, whereas Dynamic interfaces handle client payload forwarding.

Key Concept

Cisco Wireless LAN Controller Interfaces and Management Connections
Question 84Question →

A network technician is configuring switch interfaces for end-user PCs on an enterprise access switch. Which classic 802.1D Spanning Tree Protocol (STP) port states are bypassed when Cisco STP PortFast is enabled on an access interface?

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Answer: Listening and Learning

Answer

Listening and Learning
Enabling PortFast on an access port allows the interface to bypass the 802.1D Listening and Learning states (which total 30 seconds of forward delay) and transition directly into the Forwarding state as soon as the link comes up.

Step-by-Step Solution

1
Recall standard 802.1D STP port state transition sequence
Standard 802.1D ports transition sequentially through Blocking -> Listening (15s forward delay) -> Learning (15s forward delay) -> Forwarding.
Listening determines topology structure and processes BPDUs, while Learning populates MAC address tables before frame forwarding.
2
Determine the effect of enabling PortFast on an access interface
PortFast allows access ports directly connected to end-user hosts to transition immediately from Blocking to Forwarding.
Bypassing the 30-second combined Listening (15s) and Learning (15s) delay prevents host application and DHCP discovery timeouts upon link initialization.

Key Concept

STP PortFast operational behavior and state transition bypass
Estimated Time:45s
Question 85Question →

Place the steps of the Rapid PVST+ Proposal and Agreement handshake process in the correct chronological order, starting from when a designated switch initiates fast convergence on a point-to-point link to when its port enters the Forwarding state.

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Answer

The correct sequence starts with the designated switch proposing the link state, followed by the receiving switch synchronizing non-edge ports, returning an Agreement BPDU, and finally the designated switch transitioning directly to the Forwarding state.
The Rapid PVST+ (802.1w) sync process operates in a strict sequence on point-to-point links: first, a designated port proposes rapid transition; second, the neighbor switch synchronizes by blocking non-edge designated ports; third, the neighbor sends an Agreement BPDU back; fourth, the proposing port immediately moves to the Forwarding state.

Step-by-Step Solution

1
Identify the initiation of the handshake.
The designated switch transmits a Proposal BPDU to request rapid transition on the point-to-point link.
Rapid PVST+ relies on explicit point-to-point messaging rather than timer-based delays.
2
Determine the synchronization action taken by the receiver.
The receiver puts non-edge ports into the Discarding state.
This guarantees no active loops can form while the topology adapts.
3
Identify the response message.
The receiver sends an Agreement BPDU back to the proposal sender.
The agreement signals that the receiving switch has safely isolated its local ports.
4
Determine the final state transition.
The initiating designated port transitions immediately into the Forwarding state.
Upon receiving agreement, the port moves directly to forwarding without waiting for 802.1D forward delay timers.

Key Concept

Rapid PVST+ Proposal and Agreement Handshake Mechanism
Question 86Question →

A network operations center (NOC) engineer observes that workstations attached to switch SW-CORE-01 experience a 30-second initial DHCP request timeout upon link activation before successfully receiving an IP address. Interface GigabitEthernet1/0/5 is currently configured as a standard 802.1D access port. Which operational mechanism explains why enabling Cisco STP PortFast resolves this DHCP timeout issue, and what is its specific effect on STP Topology Change Notifications (TCNs)?

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Answer: PortFast allows the interface to bypass the Listening and Learning states to enter Forwarding immediately upon link up, while suppressing TCN generation when the edge port link status changes.

Answer

PortFast allows the interface to bypass the Listening and Learning states to enter Forwarding immediately upon link up, while suppressing TCN generation when the edge port link status changes.
The correct answer identifies that PortFast allows access ports connected to end hosts to transition directly to the Forwarding state without waiting through the 15-second Listening and 15-second Learning states (a total 30-second convergence delay). This eliminates initialization delays for client services such as DHCP. In addition, link state fluctuations on a PortFast-enabled port do not trigger Topology Change Notifications (TCNs), avoiding network-wide MAC address table flushing.

Step-by-Step Solution

1
Analyze standard 802.1D STP convergence behavior on access ports.
Standard 802.1D transitions through Blocking -> Listening (15s) -> Learning (15s) -> Forwarding (total 30s delay).
During the 30-second delay, frames are dropped, causing client protocols like DHCP to time out while waiting for link establishment.
2
Determine the primary operational transition bypass provided by PortFast.
PortFast moves an edge interface immediately from Blocking to Forwarding upon link bring-up.
By bypassing Listening and Learning states, connectivity is instantaneous, eliminating host initialization timeouts.
3
Analyze the secondary benefit regarding Spanning Tree Topology Change Notifications (TCNs).
PortFast suppresses TCN generation on edge link state changes.
End-user PC power cycles or disconnects should not force switches across the network to shorten their MAC table aging timers.

Key Concept

STP PortFast immediate forwarding transition and TCN suppression on access ports
Estimated Time:2m 0s
Question 87Question →

A network administrator needs to configure a routed (Layer 3) LACP EtherChannel (Port-Channel 10) using physical member interfaces GigabitEthernet0/1 and GigabitEthernet0/2, and assign the IPv4 address 10.1.1.1/30 to the bundle. Place the CLI configuration steps in the correct operational sequence from first to last.

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Answer

The correct configuration sequence is: First select physical interfaces with `interface range GigabitEthernet0/1 - 2`, second disable Layer 2 operation using `no switchport`, third associate member interfaces into LACP using `channel-group 10 mode active`, fourth enter logical interface mode via `interface Port-channel10`, and fifth configure the IPv4 address using `ip address 10.1.1.1 255.255.255.252`.
The correct operational sequence begins by selecting physical interfaces using `interface range GigabitEthernet0/1 - 2`, converting them to routed interfaces with `no switchport`, and binding them to the dynamic LACP channel group via `channel-group 10 mode active`. Next, configuration mode shifts to the created virtual interface using `interface Port-channel10`, where the IP address is configured with `ip address 10.1.1.1 255.255.255.252`.

Step-by-Step Solution

1
Select physical interfaces
Enters interface range configuration mode for GigabitEthernet0/1 and GigabitEthernet0/2.
Configuration options must be applied to physical interfaces simultaneously using interface range mode.
2
Convert interfaces to Layer 3
Removes switchport capabilities from member interfaces.
Physical member ports must be converted to routed ports with `no switchport` prior to creating a Layer 3 EtherChannel.
3
Configure LACP channel group
Creates Port-channel10 and enables active dynamic negotiation.
Executing `channel-group 10 mode active` dynamically creates the Port-channel interface using LACP.
4
Enter logical Port-Channel interface
Transitions CLI prompt to `config-if` mode for Port-channel10.
Network layer configuration parameters must be applied to the virtual interface rather than physical ports.
5
Assign IPv4 addressing
Applies IP subnet 10.1.1.1/30 to the EtherChannel logical interface.
Layer 3 EtherChannels route traffic based on the IP address assigned directly to the Port-Channel interface.

Key Concept

Layer 3 EtherChannel (LACP) CLI Configuration Sequence
Estimated Time:1m 30s
Question 88Question →

A network technician displays the active Layer 2 discovery parameters on a switch port using the `show cdp interface gigabitethernet 0/1` command and observes the following output:

text
GigabitEthernet0/1 is up, line protocol is up
Encapsulation ARPA
Sending CDP packets every 60 seconds
Holdtime is 180 seconds

If the technician disables CDP on this interface and enables Link Layer Discovery Protocol (LLDP) globally and locally, which default update timer and holdtime timer values will LLDP use?

Show answer & explanation

Answer: Update timer of 30 seconds and holdtime timer of 120 seconds

Answer

Update timer of 30 seconds and holdtime timer of 120 seconds
The correct answer specifies an update timer of 30 seconds and a holdtime timer of 120 seconds. In Cisco IOS, LLDP transmits discovery advertisements every 30 seconds by default and retains neighbor information for 120 seconds (using a holdtime multiplier of 4).

Step-by-Step Solution

1
Identify the default timer parameters for Cisco Discovery Protocol (CDP)
CDP defaults to transmitting advertisement frames every 60 seconds with a holdtime value of 180 seconds.
This establishes the baseline shown in the CLI command output.
2
Recall default timer parameters for IEEE 802.1AB Link Layer Discovery Protocol (LLDP)
LLDP defaults to an update message interval of 30 seconds and a holdtime multiplier of 4 (30×4=12030 \times 4 = 120 seconds).
Standard IEEE LLDP specifications mandate shorter advertisement intervals and holdtimes than proprietary CDP.
3
Compare the option choices to select the accurate LLDP default timer values
The option specifying an update timer of 30 seconds and a holdtime timer of 120 seconds is correct.
It accurately reflects standard Cisco IOS default behavior when LLDP is enabled.

Key Concept

CDP vs LLDP Default Timers
Question 89Question →

A network administrator needs to manually configure a Catalyst switch as the primary Root Bridge for VLAN 30 using Rapid PVST+. The switch currently has default STP settings. Which configuration change correctly sets the bridge priority, and what is the resulting Bridge Priority value advertised in the Bridge Protocol Data Units (BPDUs) for VLAN 30?

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Answer: Execute 'spanning-tree vlan 30 priority 4096'; the advertised Bridge Priority in BPDUs will be 4126.

Answer

Execute 'spanning-tree vlan 30 priority 4096'; the advertised Bridge Priority in BPDUs will be 4126.
In Rapid PVST+, the Bridge ID priority consists of a 4-bit base priority and a 12-bit System ID Extension representing the VLAN ID. The command 'spanning-tree vlan 30 priority 4096' sets the base priority to a valid multiple of 4096. When combined with the System ID Extension of 30, the switch advertises a total Bridge Priority of 4126 (4096+304096 + 30) in its BPDUs.

Step-by-Step Solution

1
Determine valid STP bridge priority configuration increments.
STP bridge priority must be configured in increments of 4096 (e.g., 0, 4096, 8192, 12288, etc.).
The 16-bit Priority field in the Bridge ID (BID) is divided into a 4-bit Priority field (multiples of 4096) and a 12-bit System ID Extension field.
2
Calculate the total advertised Bridge Priority for VLAN 30.
Base Priority (4096) + System ID Extension (VLAN 30) = 4126.
Rapid PVST+ appends the 12-bit VLAN ID to the 4-bit base priority value to form the complete 16-bit priority component of the Bridge ID.

Key Concept

Rapid PVST+ System ID Extension and Bridge Priority Calculation
Question 90Question →

A Cisco Catalyst switch running Rapid PVST+ receives BPDUs on multiple interfaces from different neighboring switches connected to the same Root Switch. Place the decision criteria in the exact sequence the switch uses to select its Root Port, starting from the first criterion evaluated to the final tie-breaker.

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Answer

The correct evaluation sequence for Root Port selection in Rapid PVST+ is: 1. Lowest cumulative Root Path Cost received in the BPDUs, 2. Lowest Sender (Designated) Bridge ID, 3. Lowest Sender (Designated) Port ID, 4. Lowest local (Receiver) Port ID.
Rapid PVST+ follows a strict 4-step decision sequence to select a single Root Port on non-root switches: 1) Lowest cumulative Root Path Cost, 2) Lowest Sender Bridge ID, 3) Lowest Sender Port ID, and 4) Lowest local (Receiver) Port ID.

Step-by-Step Solution

1
Evaluate incoming Root Path Cost
The switch identifies the port(s) offering the shortest cumulative cost to the Root Bridge.
Path cost reflects link speed and topology length, making it the primary factor for optimal routing toward the root.
2
Break ties using upstream switch identity
If path costs are equal, the port receiving BPDUs from the upstream switch with the lowest Bridge ID (Priority + MAC) is preferred.
Bridge ID serves as the first tie-breaker when multiple paths offer equal cost through different neighboring switches.
3
Break ties using upstream port identity
If candidate ports connect to the exact same upstream switch, the port connected to the lower upstream Port ID (Priority + Port Number) is selected.
Designated Port ID identifies which specific interface on the neighboring switch is sending the BPDU.
4
Break ties using local port identity
If all preceding criteria are identical (e.g., connected via a hub), the switch selects its own local interface with the lowest Port ID.
Local Port ID guarantees a deterministic decision when upstream information offers no distinction.

Key Concept

Rapid PVST+ Root Port Selection Tie-Breaker Logic
Estimated Time:1m 30s
Question 91Question →

Two Cisco switches, Switch-A and Switch-B, are linked using physical interfaces GigabitEthernet0/1 and GigabitEthernet0/2. The network team intends to aggregate these links using dynamic trunk negotiation. A technician executes `channel-group 5 mode active` on Switch-A's physical interfaces, but configures `channel-group 5 mode desirable` on Switch-B's physical interfaces.

After applying these configurations, the output of `show etherchannel summary` on Switch-A indicates a status of `Po5(SD)` with member ports showing `(D)`. Which explanation correctly accounts for this operational failure?

Show answer & explanation

Answer: LACP and PAgP are distinct negotiation protocols, causing channel negotiation to fail when combining `active` (LACP) with `desirable` (PAgP).

Answer

LACP and PAgP are distinct negotiation protocols, causing channel negotiation to fail when combining active (LACP) with desirable (PAgP).
EtherChannel links require matching protocols on both ends. Mode `active` triggers dynamic negotiation using LACP (IEEE 802.3ad), while mode `desirable` triggers dynamic negotiation using PAgP (Cisco proprietary). Because LACP and PAgP packets are incompatible, the switches cannot complete handshaking, causing the port-channel to remain down `Po5(SD)` with physical interfaces down `(D)` or standalone.

Step-by-Step Solution

1
Identify the protocol associated with each channel-group mode.
Mode `active` utilizes IEEE 802.3ad LACP, whereas mode `desirable` utilizes Cisco proprietary PAgP.
EtherChannel negotiation protocols must match on both ends of the link.
2
Analyze protocol compatibility between Switch-A and Switch-B.
Switch-A transmits LACP PDUs while Switch-B transmits PAgP packets. Neither switch understands the other's control frames.
LACP and PAgP cannot interoperate or establish a negotiated bundle.
3
Correlate protocol mismatch with CLI verification status `Po5(SD)`.
The Port-channel remains down (D) at Layer 2 (S) because dynamic negotiation fails completely.
Without successful negotiation, physical ports are kept in a down or unbundled state to prevent layer 2 loops.

Key Concept

EtherChannel Protocol and Mode Compatibility (LACP vs PAgP)
Question 92Question →

Two Cisco switches, SW1 and SW2, are interconnected using three physical links: GigabitEthernet1/0/1, GigabitEthernet1/0/2, and GigabitEthernet1/0/3. An engineer attempts to aggregate all three links into a routed Layer 3 EtherChannel (Port-channel 12).

On SW1, the engineer configures `no switchport` on `interface Port-channel 12` along with IPv4 addressing, and assigns all three physical interfaces using `channel-group 12 mode active`.

On SW2, `no switchport` and IP addressing are configured on `interface Port-channel 12`. Interfaces GigabitEthernet1/0/1 and GigabitEthernet1/0/2 are configured with `channel-group 12 mode passive`, while interface GigabitEthernet1/0/3 is configured with `channel-group 12 mode auto`.

Upon checking operational status, Port-channel 12 is up with IPv4 connectivity, but only GigabitEthernet1/0/1 and GigabitEthernet1/0/2 are bundled (`P` flag in `show etherchannel summary`), whereas GigabitEthernet1/0/3 remains unbundled (`I` flag on SW1 and `D` flag on SW2).

Which condition correctly explains why interface GigabitEthernet1/0/3 failed to join the EtherChannel bundle?

Show answer & explanation

Answer: Interface GigabitEthernet1/0/3 on SW2 is configured with PAgP mode auto, which cannot negotiate an EtherChannel bundle with SW1's LACP mode active.

Answer

Interface GigabitEthernet1/0/3 on SW2 is configured with PAgP mode auto, which cannot negotiate an EtherChannel bundle with SW1's LACP mode active.
The root cause of the bundling failure on GigabitEthernet1/0/3 is a protocol mismatch. SW1 is configured with LACP (`channel-group 12 mode active`), while SW2's GigabitEthernet1/0/3 is configured with PAgP (`channel-group 12 mode auto`). Because IEEE 802.3ad LACP and Cisco proprietary PAgP speak completely different protocol languages, negotiation fails and the link drops out of the bundle, showing standalone (`I`) or down (`D`) flags.

Step-by-Step Solution

1
Analyze negotiation protocol assignment on SW1.
SW1 uses `channel-group 12 mode active` across all three physical interfaces, designating LACP (IEEE 802.3ad) as the aggregation control protocol.
The `active` keyword explicitly enables LACP and actively sends LACP PDUs.
2
Analyze negotiation protocol assignment on SW2 member interfaces.
Interfaces Gig1/0/1 and Gig1/0/2 use `passive` (LACP), whereas Gig1/0/3 uses `auto` (PAgP).
The `auto` keyword enables Cisco proprietary PAgP, which expects PAgP packets (`desirable` or `auto`), not LACP PDUs.
3
Evaluate protocol compatibility for GigabitEthernet1/0/3.
SW1 sends LACP PDUs on Gig1/0/3, while SW2 listens for PAgP packets on Gig1/0/3. Neither switch receives compatible aggregation negotiation frames.
LACP and PAgP are incompatible protocols and cannot form an EtherChannel across opposing endpoints.

Key Concept

LACP and PAgP Mode Incompatibility in EtherChannel Aggregation
Question 93Question →

A network engineer is configuring a routed (Layer 3) EtherChannel bundle between two Cisco switches using Link Aggregation Control Protocol (LACP). Which TWO configuration steps must be performed on the physical member interfaces to correctly establish the channel?

Select all that apply

Show answer & explanation

Answer: Execute the `no switchport` command on each physical member interface.; Apply the `channel-group 1 mode active` command to the physical member interfaces.

Answer

The correct steps are executing the `no switchport` command on physical member interfaces and placing them into an active LACP mode using `channel-group 1 mode active`.
To construct a Layer 3 EtherChannel, physical member interfaces must first be converted from switchports to routed interfaces using the `no switchport` command. Next, an LACP negotiation mode (active or passive) must be configured using the `channel-group` command on those physical interfaces.

Step-by-Step Solution

1
Convert physical member interfaces to Layer 3 mode
The physical interfaces cease operating as Layer 2 switchports.
Layer 3 EtherChannels require member links to operate as routed ports.
2
Enable LACP negotiation on physical member interfaces
Physical interfaces send LACP packets to initiate bundle negotiation.
Setting the channel-group mode to active enables LACP dynamic negotiation.

Key Concept

Layer 3 LACP EtherChannel Configuration
Question 94Question →

A network administrator needs to configure a routed Layer 3 EtherChannel using LACP across physical interfaces GigabitEthernet 0/1 and 0/2 on a Cisco Catalyst switch. Drag and drop the CLI configuration steps into the correct sequential order from first to last.

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Answer

The correct sequence begins with selecting the physical interface range, disabling switchport functionality to convert them to Layer 3, defining the LACP channel group mode to generate the logical bundle, and finally entering the Port-channel interface to assign the IP address.
To create a functional Layer 3 EtherChannel using LACP, the network administrator must first access the physical member interfaces using the range command, disable Layer 2 switchport characteristics with 'no switchport', group the links into an active LACP channel group with 'channel-group 1 mode active', and finally apply the network IP addressing directly onto the resulting logical Port-channel interface.

Step-by-Step Solution

1
Select member physical interfaces
Enters interface range configuration mode for GigabitEthernet 0/1 - 2.
Configuration must begin on the target member links.
2
Convert physical ports to routed ports
Disables Layer 2 port capabilities using 'no switchport'.
Layer 3 EtherChannels require member ports to be routed ports prior to forming a Layer 3 logical port-channel.
3
Enable LACP dynamic negotiation
Creates Port-channel 1 and initiates active LACP negotiations via 'channel-group 1 mode active'.
The 'active' keyword explicitly selects LACP protocol for bundle aggregation.
4
Assign IP address to the Port-channel
Navigates to 'interface Port-channel 1' and configures 'ip address 10.1.1.1 255.255.255.252'.
In a Layer 3 EtherChannel, routing parameters and IP addresses reside on the logical port-channel interface, not on individual physical members.

Key Concept

Layer 3 EtherChannel LACP Configuration Sequence
Question 95Question →

A network administrator enables Cisco PortFast on a switch port connected directly to an end-user workstation. Which operational benefit does PortFast provide in this scenario?

Show answer & explanation

Answer: The port immediately transitions from blocking to the forwarding state, bypassing listening and learning states to prevent DHCP timeouts.

Answer

The port immediately transitions from blocking to the forwarding state, bypassing listening and learning states to prevent DHCP timeouts.
Enabling PortFast on an access port connected to an end-user device allows the port to immediately transition from blocking to forwarding. By skipping the standard listening and learning states (which take 30 seconds combined), host devices receive network access right away, preventing issue scenarios like DHCP address acquisition timing out during bootup.

Step-by-Step Solution

1
Identify the standard 802.1D Spanning Tree Protocol (STP) transition sequence.
Standard STP transitions ports through Blocking → Listening (15s) → Learning (15s) → Forwarding.
This total 30-second delay prevents temporary Layer 2 loops during topology convergence.
2
Evaluate the effect of PortFast on an access interface.
PortFast allows an edge interface connected to a host (like a workstation) to immediately enter the Forwarding state upon link activation.
End-user hosts cannot create Layer 2 switching loops, so waiting through listening and learning states is unnecessary and often causes client protocol timeouts (e.g., DHCP).

Key Concept

STP PortFast operational behavior on edge ports
Question 96Question →

A network administrator needs to configure a new WPA2-Enterprise Wireless LAN (WLAN) for client connectivity using the Cisco Wireless LAN Controller (WLC) GUI. Arrange the steps in the correct chronological order required to successfully create, configure security settings for, enable, and apply this WLAN.

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Answer

The correct procedural order is: 1) Navigate to WLANs > WLANs and select Create New, 2) Define Profile Name, SSID, and WLAN ID then click Apply, 3) Select the dynamic interface and enable Status under the General tab, 4) Configure WPA2 Policy with 802.1X under the Security > Layer 2 tab, and 5) Select the RADIUS authentication server under the AAA Servers tab and click Apply.
Creating a WLAN via the Cisco WLC web GUI follows a strict sequential process. First, navigating to WLANs > WLANs and executing 'Create New' allows entry of the basic identifying information (Profile Name, SSID, and WLAN ID). Clicking Apply creates the WLAN instance and presents the edit menu. On the General tab, the administrator maps the WLAN to a dynamic interface for VLAN access and enables the WLAN status. Next, under Security > Layer 2, WPA2 Policy and 802.1X Key Management are specified. Finally, under the AAA Servers tab, the specific RADIUS server is attached to handle 802.1X authentication, and clicking Apply saves the full configuration.

Step-by-Step Solution

1
Initiate WLAN Creation
Access the WLAN creation workflow by selecting 'Create New' from the drop-down menu on the WLANs page and clicking 'Go'.
The controller requires creating a new WLAN object before configurable tabs become available.
2
Configure Basic Identifiers
Assign the Profile Name, wireless network SSID, and unique WLAN ID, then click 'Apply'.
Applying these parameters registers the WLAN and automatically opens the WLANs > Edit page with specific configuration tabs.
3
Configure Interface Mapping & Administrative Status
On the General tab, select the mapped dynamic VLAN interface and check the Enabled box for Status.
Clients will fail to receive IP addressing or transmit traffic if the WLAN is not mapped to an operational interface and enabled.
4
Configure Layer 2 Security Mechanisms
Navigate to Security > Layer 2, select WPA+WPA2 parameters, enable WPA2 Policy, and choose 802.1X under Auth Key Management.
WPA2-Enterprise relies on 802.1X Key Management rather than PSK.
5
Bind AAA RADIUS Server & Save Settings
Navigate to the AAA Servers tab, choose the configured RADIUS server under Server 1, and click 'Apply' in the top-right corner.
802.1X authentication requests must be forwarded to a external RADIUS server for identity validation.

Key Concept

WLC GUI WLAN Creation and 802.1X Security Configuration Order
Estimated Time:2m 0s
Question 97Question →

A network technician needs to configure interface FastEthernet0/1 on a Cisco Catalyst switch to connect a host workstation. Which set of commands should be entered in interface configuration mode to explicitly set the interface as an access port and assign it to VLAN 10?

Show answer & explanation

Answer: switchport mode access
switchport access vlan 10

Answer

To configure a switch interface for a single end-user workstation, enter interface configuration mode and execute 'switchport mode access' followed by 'switchport access vlan 10'.
Executing 'switchport mode access' sets the interface to operate as a Layer 2 access interface, and 'switchport access vlan 10' assigns the interface's untagged traffic membership to VLAN 10.

Step-by-Step Solution

1
Select interface configuration mode for FastEthernet0/1.
The CLI prompt changes to Switch(config-if)#.
Configuration commands must target the specific physical interface.
2
Define port role as access mode.
The command 'switchport mode access' explicitly disables trunk negotiation and sets the interface to Layer 2 access mode.
Access ports carry traffic for a single assigned VLAN without tagging egress frames.
3
Assign the VLAN membership.
The command 'switchport access vlan 10' places interface FastEthernet0/1 into VLAN 10.
This associates all untagged traffic on this port with broadcast domain VLAN 10.

Key Concept

Access Port Assignment in Cisco IOS
Question 98Question →

Match each Cisco Wireless LAN Controller (WLC) interface to its corresponding operational characteristic and network functionality.

Click a left item, then click its matching right item

Items

Service Port
Management Interface
Virtual Interface
Dynamic Interface

Matches

Show answer & explanation

Answer

The Service Port provides out-of-band management access. The Management Interface supports in-band management and CAPWAP communication. The Virtual Interface handles internal functions like web authentication and DHCP relay. Dynamic Interfaces handle user WLAN-to-VLAN traffic mapping.
Each Cisco WLC interface serves a distinct operational purpose: the Service Port handles out-of-band management on an isolated network; the Management Interface manages in-band administrative traffic and AP CAPWAP tunnels; the Virtual Interface provides Layer 3 services like web authentication redirection and DHCP relaying; and Dynamic Interfaces segment client traffic onto specific wired VLANs.

Step-by-Step Solution

1
Identify the role of out-of-band management on Cisco controllers.
The Service Port is identified as the physical port dedicated strictly to out-of-band administrative connections.
It does not route traffic to or from dynamic interfaces or support general wireless client forwarding.
2
Identify the primary in-band management and AP control interface.
The Management Interface is selected as it manages controller administrative access via SSH/HTTPS and terminates CAPWAP tunnels from lightweight APs.
This interface is mandatory and operates in-band over trunked switchports.
3
Distinguish between internal helper interfaces and client data interfaces.
The Virtual Interface provides logical redirection and DHCP relay services, while Dynamic Interfaces act like VLAN subinterfaces for user payload traffic.
The Virtual Interface requires a unroutable placeholder IP address, whereas Dynamic Interfaces map directly to standard 802.1Q VLAN IDs.

Key Concept

Cisco WLC Physical and Logical Interface Architecture
Question 99Question →

A network technician is setting up dynamic link aggregation using Link Aggregation Control Protocol (LACP) between two Cisco switches. Which TWO channel-group mode pairings will successfully establish an operational EtherChannel bundle? (Select two.)

Select all that apply

Show answer & explanation

Answer: Both switch interfaces configured in active mode; One switch interface configured in active mode and the other in passive mode

Answer

The correct options are configuring both interfaces in active mode, and configuring one interface in active mode with the opposing interface in passive mode.
LACP EtherChannel formation requires at least one participating interface to be in active mode to send LACP frames. Thus, active-active and active-passive combinations will both form a functional bundle.

Step-by-Step Solution

1
Analyze LACP operational modes.
Active mode actively transmits LACP packets, whereas passive mode only responds to received LACP packets.
At least one endpoint must be configured in active mode to initiate the LACP packet exchange.
2
Evaluate protocol compatibility.
Desirable mode belongs to PAgP, which is incompatible with LACP.
Both switches must use matching aggregation protocols (LACP to LACP or PAgP to PAgP).

Key Concept

LACP Mode Negotiation Dynamics
Question 100Question →

Match each Layer 2 discovery protocol standard, default operational timer, or feature extension on the left with its correct specification on the right.

Click a left item, then click its matching right item

Items

IEEE 802.1AB
CDP Default Holdtime
LLDP Default Advertisement Timer
LLDP-MED

Matches

Show answer & explanation

Answer

IEEE 802.1AB matches the vendor-neutral open standard specification defining Link Layer Discovery Protocol. CDP Default Holdtime matches 180 seconds. LLDP Default Advertisement Timer matches 30 seconds. LLDP-MED matches the extension supporting inventory management, power-over-Ethernet (PoE) negotiation, and network policy discovery for IP endpoints.
Each pair correctly matches the protocol standard, operational timers, and functional extensions: IEEE 802.1AB defines open-standard LLDP, CDP uses a 180-second default holdtime (3x its 60-second update timer), LLDP sends frames every 30 seconds by default, and LLDP-MED adds organizationally specific Type-Length-Values (TLVs) for media endpoints such as IP phones.

Step-by-Step Solution

1
Identify protocol standard numbers
IEEE 802.1AB corresponds directly to the open standard protocol for LLDP.
CDP is Cisco-proprietary and has no IEEE standard number, whereas LLDP was standardized under IEEE 802.1AB.
2
Differentiate default timers between CDP and LLDP
CDP advertises every 60 seconds with a 180-second holdtime. LLDP advertises every 30 seconds with a 120-second holdtime (holdtime multiplier of 4).
Matching CDP holdtime yields 180 seconds and LLDP advertisement timer yields 30 seconds.
3
Identify media endpoint discovery extensions
LLDP-MED enhances standard LLDP specifically for VoIP phones and endpoint discovery capabilities including voice VLAN assignments and PoE capabilities.
This matches the endpoint management and policy discovery description.

Key Concept

Layer 2 Discovery Protocols (CDP and LLDP) operational specifications and standards
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