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Question 1081Question →

A network administrator assigns an IP address of 192.168.50.77/27192.168.50.77/27 to a server interface. What is the broadcast address for the subnet to which this server belongs?

Show answer & explanation

Answer: 192.168.50.95192.168.50.95

Answer

The broadcast address for the subnet containing host 192.168.50.77/27192.168.50.77/27 is 192.168.50.95192.168.50.95.
A /27/27 subnet prefix leaves 55 host bits, yielding a subnet block size of 25=322^5 = 32 addresses. Subnets increment by 3232 in the fourth octet (192.168.50.0192.168.50.0, 192.168.50.32192.168.50.32, 192.168.50.64192.168.50.64, 192.168.50.96192.168.50.96). The host address 192.168.50.77192.168.50.77 lies between 192.168.50.64192.168.50.64 and 192.168.50.95192.168.50.95. The final address in this range, 192.168.50.95192.168.50.95, is the broadcast address.

Step-by-Step Solution

1
Determine the subnet block size from the prefix length.
A /27/27 prefix leaves 32−27=532 - 27 = 5 host bits. The subnet block size (increment) is 25=322^5 = 32.
Calculating the block size identifies the boundary increments in the fourth octet.
2
Identify the subnet network boundaries in the fourth octet.
Subnet network addresses increment by 3232: .0,.32,.64,.96,.128.0, .32, .64, .96, .128, and so forth.
Listing the multiples of 3232 establishes exact subnet boundary ranges.
3
Locate the specific subnet range containing 192.168.50.77192.168.50.77.
Since 7777 falls between 6464 and 9595, the network address is 192.168.50.64192.168.50.64 and the broadcast address is 192.168.50.95192.168.50.95.
The last address in a subnet block range is reserved as the broadcast address.

Key Concept

IPv4 Subnet Calculation and Broadcast Address Identification
Estimated Time:45s
Question 1082Question →

A data center engineering team is selecting virtualization software to host enterprise services on physical hardware. The team chooses a bare-metal (Type 1) hypervisor architecture rather than a hosted (Type 2) hypervisor architecture. Which statement correctly identifies a key operational characteristic of the selected hypervisor type?

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Answer: It runs directly on the physical hardware of the server, managing hardware resources without relying on an underlying host operating system.

Answer

It runs directly on the physical hardware of the server, managing hardware resources without relying on an underlying host operating system.
A Type 1 (bare-metal) hypervisor is installed directly on the physical server hardware. It manages hardware resources natively and provides higher performance, efficiency, and security for enterprise virtualization environments because no intermediate host operating system is present.

Step-by-Step Solution

1
Analyze the core architectural definition of a Type 1 (bare-metal) hypervisor.
Identify that Type 1 hypervisors install directly onto host hardware without requiring a separate host OS.
Direct hardware control maximizes performance, scalability, and security for enterprise workloads.
2
Compare Type 1 characteristics against Type 2 hypervisors.
Recognize that hosted hypervisors (Type 2) run on top of an OS, whereas Type 1 hypervisors act as the primary operating layer directly managing physical CPU, memory, and networking.
Differentiating these architecture types is essential for CCNA virtualization fundamentals.

Key Concept

Bare-Metal (Type 1) vs. Hosted (Type 2) Hypervisors
Estimated Time:1m 0s
Question 1083Question →

A network engineer is configuring Layer 2 neighbor discovery on Cisco Catalyst switches and multi-vendor endpoints. Match each Layer 2 discovery protocol characteristic or CLI configuration element on the left with its corresponding operational parameter or behavior on the right.

Click a left item, then click its matching right item

Items

Cisco Discovery Protocol (CDP) Default Timers
Link Layer Discovery Protocol (LLDP) Default Timers
LLDP Interface Directional Control Syntax
LLDP-MED (ANSI/TIA-1057) Capability Target

Matches

Show answer & explanation

Answer

CDP Default Timers match with a 60-second update transmission interval and 180-second holdtime. LLDP Default Timers match with a 30-second update transmission interval and 120-second holdtime (holdtime multiplier of 4). LLDP Interface Directional Control Syntax matches with granular subcommands allowing outbound frame sending and inbound frame processing to be controlled independently per interface. LLDP-MED Capability Target matches with extending discovery to endpoint devices for voice VLAN assignment, location details, and dynamic Power over Ethernet (PoE) negotiation.
The correct mapping aligns CDP with its proprietary default timers (60s update / 180s holdtime), LLDP with IEEE 802.1AB default timers (30s update / 120s holdtime calculated via a multiplier of 4), interface-level LLDP directional control ('lldp transmit' and 'lldp receive'), and LLDP-MED with multi-vendor endpoint management features (voice VLAN provisioning and dynamic PoE allocation).

Step-by-Step Solution

1
Evaluate the default transmission and holdtime values for CDP and standard LLDP.
CDP defaults to sending announcements every 60 seconds with a 180-second holdtime. IEEE 802.1AB LLDP defaults to sending frames every 30 seconds with a holdtime multiplier of 4 (giving a 120-second holdtime).
Identifying the exact timer specifications avoids confusing vendor-proprietary timer defaults with IEEE standard defaults.
2
Analyze interface configuration mechanisms for directional frame control.
CDP is toggled per interface with 'cdp enable'. LLDP provides independent control over transmission ('lldp transmit') and reception ('lldp receive') at the interface level.
Network security policies often mandate disabling advertisement transmissions on public-facing or untrusted access ports while still permitting inbound neighbor logging.
3
Identify protocol extensions for specialized media endpoints like IP phones.
LLDP-MED (ANSI/TIA-1057) builds upon IEEE 802.1AB by defining specific Type-Length-Value (TLV) headers for Voice VLAN configuration, physical location tracking, and granular power-via-MDI negotiation.
Multi-vendor VoIP deployments rely on LLDP-MED to achieve seamless endpoint provisioning on non-Cisco switches or cross-vendor telephony platforms.

Key Concept

Layer 2 Discovery Protocols (CDP and LLDP Parameters and Configurations)
Question 1084Question →

A network administrator needs to create VLAN 100 named VOICE on a Cisco Catalyst switch and assign interface GigabitEthernet0/2 as a static access port in VLAN 100. Starting from Privileged EXEC mode (Switch#Switch\#), in what sequence must the Cisco IOS CLI commands be executed?

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct command sequence begins with entering global configuration mode (configure terminal), creating VLAN 100 (vlan 100), naming the VLAN (name VOICE), navigating to interface GigabitEthernet0/2 (interface gigabitethernet0/2), configuring access mode (switchport mode access), and assigning the port to VLAN 100 (switchport access vlan 100).
The correct order follows Cisco IOS configuration hierarchy. The sequence starts in Privileged EXEC mode with 'configure terminal' to enter Global Configuration mode. Next, 'vlan 100' creates the VLAN and switches to VLAN Configuration mode, where 'name VOICE' is applied. After returning to global configuration scope, 'interface gigabitethernet0/2' opens Interface Configuration mode, where 'switchport mode access' enforces static access behavior and 'switchport access vlan 100' places the port into VLAN 100.

Step-by-Step Solution

1
Transition from Privileged EXEC mode to Global Configuration mode.
The CLI prompt changes to Switch(config)#.
Global configuration mode is required to configure system-wide parameters and enter specific subconfiguration modes.
2
Create VLAN 100 and enter VLAN Configuration submode.
The CLI prompt changes to Switch(config-vlan)#.
VLAN 100 must be instantiated before configuring its parameters or assigning ports.
3
Assign the name VOICE to VLAN 100.
VLAN 100 is assigned the descriptive name VOICE.
The 'name' command is specific to VLAN configuration mode.
4
Navigate to Interface Configuration mode for GigabitEthernet0/2.
The CLI prompt changes to Switch(config-if)#.
Targeting an interface requires switching from global configuration to interface configuration mode.
5
Configure GigabitEthernet0/2 as a static access port.
Trunk negotiation is disabled, establishing static access operation.
Executing 'switchport mode access' explicitly defines the interface operational mode.
6
Assign GigabitEthernet0/2 to VLAN 100.
Untagged frames entering GigabitEthernet0/2 are assigned to broadcast domain VLAN 100.
Executing 'switchport access vlan 100' maps the access port to VLAN 100.

Key Concept

Cisco IOS hierarchical context navigation and sequential syntax execution for VLAN creation and static access port configuration.
Question 1085Question →

A network administrator configures Cisco STP PortFast globally on an enterprise access switch. Which two operational benefits or characteristics occur when PortFast is active on an access port connected to a host workstation? (Select two.)

Select all that apply

Show answer & explanation

Answer: The port immediately transitions from the Blocking state to the Forwarding state, skipping the Listening and Learning states.; The switch prevents the generation of Topology Change Notifications (TCNs) when the interface changes link state.

Answer

The correct benefits are that the interface transitions immediately to the Forwarding state (bypassing Listening and Learning states) and that the switch avoids sending Topology Change Notifications (TCNs) when the port status changes.
PortFast is intended for edge ports connected to single end-hosts (such as PCs or printers). It provides two core benefits: immediate transition to the Forwarding state (bypassing the 30-second total Listening and Learning delay) and preventing linkup/linkdown events on host ports from generating Topology Change Notifications (TCNs) that force CAM table aging across the network.

Step-by-Step Solution

1
Analyze standard 802.1D STP convergence timers on edge ports.
Standard STP ports undergo Listening (15 seconds) and Learning (15 seconds) states before reaching Forwarding (total 30 seconds delay), which can cause DHCP client timeouts on host devices.
Identify the primary operational problem PortFast is designed to solve.
2
Evaluate the direct state transition change caused by PortFast.
PortFast allows edge ports to transition immediately from Blocking to Forwarding, bypassing the 30-second convergence delay.
Confirm the first correct operational trait of PortFast.
3
Evaluate the network-wide impact of edge port state changes.
PortFast suppresses TCN generation on edge link flaps, protecting the switch fabric from unnecessary MAC table age-out events.
Confirm the second correct operational benefit of PortFast.

Key Concept

Cisco STP PortFast Operational Behavior and TCN Suppression
Estimated Time:1m 15s
Question 1086Question →

An engineer is troubleshooting a routed (Layer 3) EtherChannel between Switch-A and Switch-B. The output of `show etherchannel summary` on Switch-A displays the following status:

text
Group Port-channel Protocol Ports
------+------------+----------+-----------------------------------
10 Po10(SD) LACP Gi0/1(I) Gi0/2(I)

Flags: S - Layer3, D - Down, I - Stand-alone

Switch-A's physical interfaces GigabitEthernet0/1 and GigabitEthernet0/2 are configured with `no switchport` and `channel-group 10 mode active` under interface configuration mode.

Which remote configuration on Switch-B explains why the physical member interfaces on Switch-A remain in a stand-alone (I) state and the port-channel is down (SD)?

Show answer & explanation

Answer: Switch-B has configured member interfaces with `channel-group 10 mode auto`.

Answer

Switch-B has configured member interfaces with `channel-group 10 mode auto`.
The option stating that Switch-B has configured member interfaces with `channel-group 10 mode auto` is correct because `mode auto` enables PAgP negotiation. PAgP and LACP are mutually incompatible protocols; an LACP active interface will never form an EtherChannel with a PAgP auto interface, leaving local ports in the stand-alone (I) state.

Step-by-Step Solution

1
Analyze the `show etherchannel summary` output and flags on Switch-A.
The port-channel Po10 is flagged as `SD` (Layer 3, Down) and member ports Gi0/1 and Gi0/2 are marked with flag `I` (Stand-alone).
Flag `I` indicates the switch is operating physical ports individually because dynamic aggregation negotiation has failed.
2
Examine the local channel-group configuration and protocol on Switch-A.
Switch-A uses LACP (`channel-group 10 mode active`).
An LACP active port sends LACP Data Units (LACPDUs) to solicit aggregation from the remote peer.
3
Evaluate peer negotiation protocol compatibility.
PAgP modes (`auto` and `desirable`) are incompatible with LACP modes (`active` and `passive`).
If Switch-B is configured with `mode auto`, it uses Cisco proprietary PAgP, which does not process or respond to IEEE 802.3ad LACP packets, preventing bundle formation.

Key Concept

LACP vs PAgP Protocol Compatibility and Operational State Verification
Question 1087Question →

A network engineer configures Cisco STP PortFast on access layer switch interfaces connected to end-user workstations. Which two statements correctly describe the operational impacts and characteristics of enabling PortFast on these interfaces? (Select TWO.)

Select all that apply

Show answer & explanation

Answer: The interface immediately transitions from the Blocking state to the Forwarding state upon linkup, completely bypassing the Listening and Learning states.; The switch suppresses the generation of Topology Change Notifications (TCNs) when the link state on the PortFast-enabled port transitions up or down.

Answer

PortFast allows an access port to immediately enter the Forwarding state by bypassing the Listening and Learning states, and it suppresses Topology Change Notifications (TCNs) when the port link state changes.
Enabling PortFast on an access interface allows it to bypass the traditional 15-second Listening and 15-second Learning states, transitioning immediately to the Forwarding state. Additionally, PortFast suppresses Topology Change Notifications (TCNs) when the link flaps, preventing unnecessary network-wide MAC address table aging.

Step-by-Step Solution

1
Analyze STP state transitions with PortFast
Standard 802.1D transitions through Blocking (20s max age) -> Listening (15s) -> Learning (15s) -> Forwarding. PortFast immediately places access ports into Forwarding mode upon linkup.
This bypasses the 30-second forward delay, allowing end devices to acquire DHCP IP addresses without timing out.
2
Evaluate Topology Change Notification (TCN) behavior
Link flaps on PortFast-enabled ports do not cause the switch to generate TCN BPDUs toward the Root Bridge.
Prevents unnecessary flooding and shortening of MAC table aging timers across the switch network when user PCs power on or off.
3
Evaluate BPDU handling and security misconceptons
PortFast ports continue to transmit and receive BPDUs unless BPDU Guard or BPDU Filter features are added.
A common misconception is that PortFast disables BPDUs; connecting a switch to a PortFast port without BPDU Guard can lead to transient switching loops.

Key Concept

STP PortFast Operational Characteristics and TCN Suppression
Question 1088Question →

A network engineer is configuring an unassigned interface on a Cisco Catalyst switch. The engineer enters interface configuration mode for GigabitEthernet 0/8 and executes the following command sequence:

text
Switch(config)# interface gigabitethernet 0/8
Switch(config-if)# switchport access vlan 42

Prior to entering these commands, VLAN 42 was not present in the switch VLAN database. Assuming default Cisco IOS switchport configuration settings, which outcome occurs as a result of this configuration?

Show answer & explanation

Answer: VLAN 42 is automatically created in the switch VLAN database, and interface GigabitEthernet 0/8 is assigned to forward untagged traffic exclusively within VLAN 42's broadcast domain.

Answer

VLAN 42 is automatically created in the switch VLAN database, and interface GigabitEthernet 0/8 is assigned to forward untagged traffic exclusively within VLAN 42's broadcast domain.
In Cisco IOS, executing 'switchport access vlan <vlan-id>' on an interface when the specified VLAN does not exist causes the switch to automatically create the VLAN in the VLAN database and assign the interface to it. The interface then functions as an access port operating exclusively within the designated broadcast domain.

Step-by-Step Solution

1
Analyze the execution of 'switchport access vlan 42' on a non-existent VLAN ID in Cisco IOS.
Cisco IOS checks the VLAN database. Finding no existing VLAN 42, it generates a console notification ('VLAN 42 does not exist. Creating vlan 42') and automatically adds VLAN 42 with default settings.
Cisco IOS provides dynamic VLAN auto-creation upon assignment to access interfaces to streamline port assignment.
2
Determine the operational state and Layer 2 boundary of GigabitEthernet 0/8.
The port is assigned to access VLAN 42, placing all connected host untagged traffic into VLAN 42's distinct broadcast domain.
Access ports belong to a single access VLAN and process untagged Ethernet frames within that specific broadcast domain.

Key Concept

VLAN Auto-Creation and Access Port Broadcast Domain Isolation
Question 1089Question →

A network engineer is operating a four-switch topology (Switch-A, Switch-B, Switch-C, and Switch-D) running Rapid PVST+ for VLAN 50. All inter-switch links are 1 Gbps 802.1Q trunks operating with standard IEEE 802.1D short path costs (cost = 4).

The configured base bridge priorities and MAC addresses for VLAN 50 are as follows:
• Switch-A: Base Priority 24576, MAC 0010.1111.1111
• Switch-B: Base Priority 24576, MAC 0010.2222.2222
• Switch-C: Base Priority 28672, MAC 0010.3333.3333
• Switch-D: Base Priority 32768, MAC 0010.4444.4444

Link connections:
��� Switch-C connects to Switch-A via GigabitEthernet0/1.
• Switch-C connects to Switch-B via GigabitEthernet0/2.
• Switch-D connects directly to Switch-A via GigabitEthernet0/1.
• Switch-D connects directly to Switch-B via GigabitEthernet0/2.
• Switch-A and Switch-B are connected together via two parallel 1 Gbps trunks: Trunk-1 (Gi0/1 on both) and Trunk-2 (Gi0/2 on both). On Switch-A, interface Gi0/1 has port priority 112, and Gi0/2 has port priority 128 (default).

Based on Rapid PVST+ operations for VLAN 50, which port role and state are assigned to interface GigabitEthernet0/2 on Switch-C?

Show answer & explanation

Answer: Alternate port in the Discarding state

Answer

Interface GigabitEthernet0/2 on Switch-C is assigned the Alternate port role and is placed in the Discarding state.
Switch-A is elected Root Bridge for VLAN 50 due to having the lowest Bridge ID (Priority 24576+50=2462624576 + 50 = 24626, MAC 0010.1111.1111). Switch-C's interface Gi0/1 connects directly to Switch-A with a cumulative path cost of 4, making Gi0/1 the Root Port. Interface Gi0/2 on Switch-C connects to Switch-B. Both Switch-B and Switch-C have a Root Path Cost of 4 to reach Switch-A. When electing the Designated Port for the segment connecting Switch-B and Switch-C, Switch-B wins because its Bridge ID (24626.0010.2222.222224626.0010.2222.2222) is lower than Switch-C's Bridge ID (28722.0010.3333.333328722.0010.3333.3333). Therefore, Switch-B's interface becomes Designated Forwarding, and Switch-C's interface Gi0/2 becomes an Alternate port in the Discarding state.

Step-by-Step Solution

1
Calculate the Bridge ID for each switch for VLAN 50 by adding the System ID Extension (VLAN ID 50) to the base bridge priority.
Switch-A Bridge ID: 24576+50=2462624576 + 50 = 24626 with MAC 0010.1111.1111.
Switch-B Bridge ID: 24576+50=2462624576 + 50 = 24626 with MAC 0010.2222.2222.
Switch-C Bridge ID: 28672+50=2872228672 + 50 = 28722 with MAC 0010.3333.3333.
Switch-D Bridge ID: 32768+50=3281832768 + 50 = 32818 with MAC 0010.4444.4444.
Rapid PVST+ uses the 12-bit System ID Extension added to the 4-bit priority field to uniquely identify the bridge priority for each VLAN.
2
Determine the Root Bridge for VLAN 50.
Switch-A is elected Root Bridge because Switch-A and Switch-B tie on priority (24626), but Switch-A has the lower MAC address (0010.1111.1111 < 0010.2222.2222).
The switch with the lowest numerical Bridge ID (Priority + Sys-ID + MAC) becomes the Root Bridge.
3
Determine the Root Port for Switch-C.
Switch-C Gi0/1 connects directly to Root Bridge Switch-A with path cost 4. Switch-C Gi0/2 connects to Switch-B, which has a path cost of 4 to Switch-A (via Gi0/1), making the path via Gi0/2 cost 4+4=84 + 4 = 8. Thus, Switch-C Gi0/1 is the Root Port (Forwarding).
Root Port is selected based on the lowest cumulative Root Path Cost.
4
Determine the role of Switch-C GigabitEthernet0/2 on the link connecting Switch-C and Switch-B.
Both Switch-B and Switch-C advertise a Root Path Cost of 4 on this segment. To elect the Designated Port for the link, compare Bridge IDs of the advertising switches: Switch-B (24626.0010.2222.2222) vs Switch-C (28722.0010.3333.3333). Switch-B has the lower Bridge ID, so Switch-B Gi0/1 becomes the Designated Port (Forwarding). Consequently, Switch-C Gi0/2 becomes an Alternate Port and enters the Discarding state.
In Rapid PVST+, a non-root port receiving superior BPDUs from another switch on a point-to-point link becomes an Alternate port in the Discarding state to maintain a loop-free topology.

Key Concept

Rapid PVST+ Root Bridge Election, Path Cost Calculation, and Alternate Port Role Assignment
Question 1090Question →

A network engineer is deploying a Cisco Lightweight Access Point (AP) operating in Local mode. The AP needs to establish a CAPWAP tunnel back to the central Wireless LAN Controller (WLC). Which switch port configuration is required for the access switch interface connected directly to this AP?

Show answer & explanation

Answer: An access port assigned to the untagged VLAN used for AP management traffic.

Answer

An access port assigned to the untagged VLAN used for AP management traffic.
In Local mode, a Cisco Lightweight AP encapsulates all client traffic inside a CAPWAP tunnel sent back to the WLC. Because individual WLAN client VLANs are managed centrally at the controller, the switch port connected to the AP only needs to transmit untagged management traffic. Therefore, configuring the port as an access port in the AP's management VLAN is the correct method.

Step-by-Step Solution

1
Identify the operational mode of the Access Point.
The AP is operating in Local mode.
Local mode APs tunnel all user traffic and management frames directly to the Wireless LAN Controller via CAPWAP.
2
Determine the network access requirement for Local mode AP traffic.
The AP only requires Layer 3 IP reachability to the WLC's management IP address.
Because client VLAN traffic is not locally bridged by the AP, user VLANs do not need to be trunked to the AP.
3
Select the appropriate switch port configuration.
Configure the switch port as a standard Layer 2 access port in the AP management VLAN.
An access port provides the untagged connectivity necessary for the AP to receive an IP address and reach the controller.

Key Concept

Access Point Switchport Configuration in Local Mode
Question 1091Question →

A network technician is auditing host IP configurations across an enterprise network. Which of the following IPv4 addresses belong to RFC 1918 private address space? (Select TWO.)

Select all that apply

Show answer & explanation

Answer: 10.50.100.1; 172.20.15.5

Answer

The addresses 10.50.100.1 and 172.20.15.5 are private IPv4 addresses designated by RFC 1918.
The addresses 10.50.100.1 and 172.20.15.5 are correct because they reside inside RFC 1918 private IPv4 spaces: 10.0.0.0/8 (10.0.0.0 to 10.255.255.255) and 172.16.0.0/12 (172.16.0.0 to 172.31.255.255), respectively.

Step-by-Step Solution

1
Recall the defined RFC 1918 private IPv4 address blocks
The three RFC 1918 private blocks are: 10.0.0.0/810.0.0.0/8 (10.0.0.010.0.0.0 – 10.255.255.25510.255.255.255), 172.16.0.0/12172.16.0.0/12 (172.16.0.0172.16.0.0 – 172.31.255.255172.31.255.255), and 192.168.0.0/16192.168.0.0/16 (192.168.0.0192.168.0.0 – 192.168.255.255192.168.255.255).
RFC 1918 reserves these specific ranges for unrouted, internal IP addressing.
2
Evaluate each choice against the reserved ranges
The address 10.50.100.110.50.100.1 falls inside 10.0.0.0/810.0.0.0/8 and 172.20.15.5172.20.15.5 falls inside 172.16.0.0/12172.16.0.0/12. However, 172.32.10.1172.32.10.1 exceeds the upper limit of 172.31.255.255172.31.255.255, and 192.169.1.10192.169.1.10 falls outside 192.168.0.0/16192.168.0.0/16.
Addresses outside the three designated blocks are globally routable public addresses.

Key Concept

RFC 1918 Private IPv4 Address Allocation
Question 1092Question →

Match each network topology architecture to its corresponding operational characteristic and traffic flow optimization profile.

Click a left item, then click its matching right item

Items

Spine-Leaf (Clos) Fabric
Traditional 3-Tier Campus
Collapsed Core (2-Tier)
WAN Hub-and-Spoke

Matches

Show answer & explanation

Answer

Spine-Leaf (Clos) Fabric matches with East-West low-latency traffic using ECMP; Traditional 3-Tier Campus matches with separate functional tiers for structured North-South flow; Collapsed Core matches with combining core and distribution functions into a single switch pair; WAN Hub-and-Spoke matches with centralizing inspection and routing remote branch traffic through a central hub site.
Each topology architecture addresses specific scalability, redundancy, and traffic flow requirements: Spine-Leaf optimizes East-West data center flows using ECMP over a two-tier bipartite mesh; Traditional 3-Tier structures campus environments into distinct access, distribution, and core roles for policy control; Collapsed Core merges core and distribution layers for smaller networks to lower cost; WAN Hub-and-Spoke centralizes security and reduces link costs by routing branch-to-branch traffic through a central hub.

Step-by-Step Solution

1
Analyze the structural traffic requirements of modern data center versus campus environments.
Identified that Spine-Leaf designs specifically target East-West (server-to-server) traffic via non-blocking ECMP routing across spine switches.
Data center workloads require low, deterministic latency across leaf switches regardless of physical placement.
2
Evaluate the functional division of campus topologies.
Identified that 3-Tier Campus separates core, distribution, and access, placing policy enforcement at the distribution layer, whereas Collapsed Core merges core and distribution into a single switch pair for smaller footprints.
Merging layers reduces cost in smaller networks, while dedicated tiers scale policy enforcement in larger enterprise networks.
3
Examine wide area network (WAN) deployment topologies.
Identified Hub-and-Spoke as the topology that centralizes policy enforcement and minimizes WAN link costs by routing all branch communications through a central hub.
Full mesh topologies require far more connections, making hub-and-spoke cost-effective when central security inspection is required.

Key Concept

Enterprise Network Topology Architectures and Traffic Flow Characteristics
Estimated Time:1m 30s
Question 1093Question →

An enterprise wireless administrator is integrating a Cisco 5520 Wireless LAN Controller (running AireOS) with a Cisco Catalyst switch stack. The administrator connects four physical distribution system ports on the controller to switch interfaces GigabitEthernet1/0/1 through 1/0/4. The switch interfaces are configured as an 802.1Q trunk bundle using the command `channel-group 1 mode active`. Although Link Aggregation (LAG) has been enabled on the WLC and the controller has been rebooted, the EtherChannel fails to form and all controller distribution links remain down. Which modification on the Catalyst switch stack will resolve this connection failure?

Show answer & explanation

Answer: Change the negotiation protocol on the switch interfaces by executing `channel-group 1 mode on`.

Answer

Change the switch port EtherChannel configuration to static ON mode using `channel-group 1 mode on`.
When Link Aggregation (LAG) is enabled on a Cisco AireOS Wireless LAN Controller, all physical distribution system ports are merged into a single logical interface. AireOS controllers do not support dynamic negotiation protocols such as Link Aggregation Control Protocol (LACP) or Port Aggregation Protocol (PAgP). Therefore, the connected switch ports must be explicitly configured with static link aggregation using the command `channel-group <id> mode on`. Configuring `mode active` forces the switch to expect LACP frames, which the WLC will never transmit, causing the channel to remain down.

Step-by-Step Solution

1
Identify the controller platform and operating system requirements for Link Aggregation (LAG).
Cisco AireOS Wireless LAN Controllers require static EtherChannel bonding across all active distribution system ports.
AireOS software does not support dynamic link aggregation protocols such as LACP (`mode active`/`mode passive`) or PAgP (`mode desirable`/`mode auto`).
2
Analyze the current switch configuration.
The switch interfaces are set to `channel-group 1 mode active`, which requires LACP negotiation packets from the connected device.
Because the AireOS WLC never sends LACP frames, the switch ports remain suspended in an unbundled state awaiting negotiation.
3
Determine the necessary configuration change on the switch ports.
Change `channel-group 1 mode active` to `channel-group 1 mode on` on all connecting interfaces.
Configuring `mode on` disables negotiation protocol requirements and forces the switch interfaces into a functional EtherChannel bundle matching the WLC behavior.

Key Concept

WLAN Controller Link Aggregation (LAG) EtherChannel Switch Configuration
Question 1094Question →

An administrator is configuring edge interfaces on a Cisco Catalyst switch connected directly to end-user host computers. Which two operational characteristics or benefits occur when Cisco PortFast is enabled on these access ports?

Select all that apply

Show answer & explanation

Answer: The interface transitions immediately to the Forwarding state by bypassing the Listening and Learning states.; The switch prevents Topology Change Notifications (TCNs) from being generated when the link state on the port toggles.

Answer

PortFast allows access interfaces connected to host devices to bypass Listening and Learning states to transition immediately into Forwarding, and suppresses Topology Change Notifications (TCNs) when host links change state.
Enabling PortFast on an access port allows host devices to bypass the standard 802.1D Listening and Learning states (saving 30 seconds) and enter the Forwarding state immediately upon link initialization. Furthermore, because end hosts frequently turn on and off, PortFast suppresses Topology Change Notifications (TCNs) for those ports, preventing unnecessary MAC address table aging across the switch network.

Step-by-Step Solution

1
Identify the primary operational function of Cisco STP PortFast on access ports.
PortFast allows an edge interface to skip the traditional 802.1D Listening (15s) and Learning (15s) states, placing the port immediately into the Forwarding state upon link up.
End-user workstations do not create Layer 2 loops, so waiting for standard convergence timers is unnecessary and can cause application timeouts (such as DHCP).
2
Identify the network-wide benefit regarding Spanning Tree topology notifications.
The switch does not generate Topology Change Notifications (TCNs) when a PortFast-enabled port goes up or down.
Preventing TCN generation for simple workstation reboots avoids constantly flushing MAC address tables on all switches across the Layer 2 domain.

Key Concept

Cisco STP PortFast operation and benefits on edge access ports
Question 1095Question →

A network administrator manually configures a switch running Rapid PVST+ with a base bridge priority of 28672 for VLAN 100. What total priority value will be transmitted in the Bridge Identifier (BID) within BPDUs generated for VLAN 100 on this switch?

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Answer: 28772

Answer

28772 is the total bridge priority advertised in the BPDUs for VLAN 100 because Rapid PVST+ adds the VLAN ID (100) to the configured base bridge priority (28672).
In Rapid PVST+, Cisco switches append the 12-bit VLAN ID (System ID Extension) to the 4-bit configurable base priority. Adding the VLAN ID of 100 to the base priority of 28672 yields a total priority value of 28772.

Step-by-Step Solution

1
Identify the base bridge priority and the VLAN ID.
Base priority is 28672 and VLAN ID is 100.
Rapid PVST+ uses the 802.1t System ID Extension mechanism.
2
Calculate total priority by adding the System ID Extension (VLAN ID) to the base priority.
28672+100=2877228672 + 100 = 28772
The 16-bit Priority field in the BID consists of a 4-bit Priority field (multiples of 4096) and a 12-bit System ID Extension field.

Key Concept

Rapid PVST+ System ID Extension and Bridge Identifier (BID) Calculation
Estimated Time:45s
Question 1096Question →

An administrator executes the following command on a Cisco Catalyst switch port connected to an unmanaged access switch:

`Switch(config-if)# spanning-tree portfast`

Shortly after, a transient Layer 2 loop brings down the network segment before STP can converge. Which operational characteristic of Cisco PortFast directly allowed this loop to form?

Show answer & explanation

Answer: PortFast transitions the interface immediately from Blocking to Forwarding, bypassing the Listening and Learning states that normally detect loops.

Answer

PortFast transitions the interface immediately from Blocking to Forwarding, bypassing the Listening and Learning states that normally detect loops.
Enabling PortFast on an access port allows it to immediately transition from Blocking directly into the Forwarding state, bypassing the 15-second Listening state and 15-second Learning state. When connected to another switch (even an unmanaged one), this immediate transition to Forwarding creates a transient or permanent Layer 2 loop before STP has the chance to listen for BPDUs and move redundant ports into the Blocking state.

Step-by-Step Solution

1
Analyze standard 802.1D STP state transitions for a newly connected link.
Standard ports move through Blocking → Listening (15 seconds) → Learning (15 seconds) → Forwarding (total delay of 30 seconds).
The Listening and Learning states allow the switch to receive BPDUs and build MAC address tables to detect potential loops before user traffic is forwarded.
2
Evaluate the behavior of enabling PortFast on an interface.
PortFast skips Listening and Learning, bringing the interface directly into the Forwarding state upon link-up.
This is intended for edge end-user devices (workstations, printers) that cannot cause Layer 2 loops.
3
Determine the impact of enabling PortFast on a switch-to-switch link (or link connected to an unmanaged switch).
Because the port immediately enters Forwarding state, broadcast traffic and loops occur instantly before BPDUs can be evaluated to block the redundant path.
Misapplying PortFast on non-edge ports bypasses loop-prevention safeguards.

Key Concept

Cisco PortFast operational mechanism and misconfiguration risks on switch interconnects.
Question 1097Question →

A network administrator is connecting Switch-1 and Switch-2 using a dual-link EtherChannel across GigabitEthernet0/1 and GigabitEthernet0/2 interfaces. On Switch-1, the member interfaces are configured with `channel-group 10 mode active`. What will happen if the corresponding physical interfaces on Switch-2 are configured with `channel-group 10 mode passive`?

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Answer: The EtherChannel bundle will successfully form because active mode actively initiates LACP negotiation while passive mode responds to incoming LACP packets.

Answer

The EtherChannel bundle will successfully form because active mode actively initiates LACP negotiation while passive mode responds to incoming LACP packets.
Link Aggregation Control Protocol (IEEE 802.3ad / 802.1AX) uses active and passive negotiation modes. The active keyword causes the switch port to actively initiate negotiation by transmitting LACP packets. The passive keyword configures the port to respond to received LACP packets without sending them unprompted. Therefore, combining an active port on one side with a passive port on the other side successfully forms an EtherChannel.

Step-by-Step Solution

1
Analyze Switch-1's LACP mode configuration.
Switch-1 is set to 'active', meaning it sends LACP frames out of the interfaces to negotiate the bundle.
LACP active mode actively initiates link aggregation negotiations.
2
Analyze Switch-2's LACP mode configuration.
Switch-2 is set to 'passive', meaning it does not initiate LACP negotiation but responds when it receives LACP frames.
LACP passive mode listlessly waits for received LACP packets before forming an EtherChannel.
3
Determine the resulting channel negotiation status.
Active mode sends LACP frames, passive mode receives and responds to them, allowing the bundle to successfully form.
Active-to-Active and Active-to-Passive combinations establish LACP EtherChannels, whereas Passive-to-Passive fails.

Key Concept

LACP EtherChannel Negotiation Modes (Active and Passive)
Estimated Time:1m 30s
Question 1098Question →

A network engineer must manually configure a routed (Layer 3) Link Aggregation Control Protocol (LACP) EtherChannel bundle on a Cisco Catalyst switch using physical member interfaces GigabitEthernet1/0/1 and GigabitEthernet1/0/2. The EtherChannel must use Port-channel 20 and be configured with IP address 10.20.20.1/30. Arrange the CLI configuration commands into the correct execution sequence from top to bottom.

Drag items to arrange them in the correct order

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Answer

The correct CLI sequence is: 1) interface range GigabitEthernet1/0/1 - 2, 2) no switchport, 3) channel-group 20 mode active, 4) interface Port-channel 20, and 5) ip address 10.20.20.1 255.255.255.252.
To successfully deploy a routed (Layer 3) LACP EtherChannel, physical interfaces must first be selected, configured with 'no switchport' to disable Layer 2 switching, and bound to a channel group using an active LACP mode. Afterwards, the administrator enters the logical port-channel interface context to configure the IP address parameters.

Step-by-Step Solution

1
Select physical member interfaces
Enters interface range configuration mode for GigabitEthernet1/0/1 and GigabitEthernet1/0/2.
Configuration must start at physical interfaces to prepare them before bundling.
2
Convert physical interfaces to Layer 3 routed interfaces
Disables Layer 2 switching capabilities on physical member ports.
Physical member ports of a routed EtherChannel must have 'no switchport' applied before participating in a Layer 3 channel group.
3
Assign interfaces to an active LACP channel group
Creates Port-channel 20 automatically and sets LACP mode to active.
The 'mode active' parameter enables LACP dynamic negotiation on the physical member interfaces.
4
Select logical Port-channel interface
Enters interface configuration mode for Port-channel 20.
Network configuration, including IP addressing, must be applied directly to the logical port-channel container.
5
Configure IP address on Port-channel interface
Assigns IPv4 address 10.20.20.1/30 to Port-channel 20.
Layer 3 EtherChannels hold IP addressing at the port-channel level rather than individual member links.

Key Concept

Layer 3 EtherChannel (LACP) Configuration Sequence
Question 1099Question →

A network administrator is assigning an IP address to a router interface using a CIDR prefix length of /26/26. Which dotted-decimal subnet mask corresponds to this prefix?

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Answer: 255.255.255.192

Answer

255.255.255.192
A CIDR prefix of /26 indicates that 26 bits are set to 1 in the subnet mask. The first 24 bits populate the first three octets fully as 255.255.255. The remaining 2 network bits in the fourth octet correspond to binary 11000000, which equals 128+64=192128 + 64 = 192, producing the dotted-decimal subnet mask 255.255.255.192.

Step-by-Step Solution

1
Determine the bit allocation across octets for a /26 prefix.
The first three octets use 24 bits (8 + 8 + 8 = 24), leaving 2 network bits for the fourth octet.
An IPv4 subnet mask has 32 total bits.
2
Convert the 2 network bits in the fourth octet to decimal.
Binary 11000000 equals 128+64=192128 + 64 = 192.
Subnet mask bits are filled from left to right.
3
Combine all four octets in dotted-decimal format.
255.255.255.192
The first three octets consist of 8 set bits each, yielding 255.255.255.

Key Concept

Converting CIDR notation to dotted-decimal subnet masks
Estimated Time:45s
Question 1100Question →

Which IEEE 802.1D Spanning Tree Protocol (STP) port state populates the switch MAC address table using source MAC addresses of received frames, but does not yet forward user data frames?

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Answer: Learning

Answer

Learning
Under legacy 802.1D Spanning Tree Protocol, the Learning state acts as a transition phase between Listening and Forwarding. During this state, the switch port receives data frames and inspects source MAC addresses to populate its address table, but it continues to drop data traffic to maintain a loop-free environment.

Step-by-Step Solution

1
Analyze the operational requirements stated in the prompt.
The port state must populate the MAC address table based on incoming frame headers while continuing to discard user data frames.
Building the MAC address table before enabling full data transfer minimizes initial unicast flooding once data forwarding begins.
2
Evaluate the 802.1D STP port states against these requirements.
Blocking discards user data and does not learn MAC addresses. Listening evaluates network topology BPDUs without learning MAC addresses. Learning populates the MAC table but discards data frames. Forwarding both populates MAC tables and forwards data frames.
Only the Learning state satisfies the specific condition of MAC learning without data forwarding.

Key Concept

STP 802.1D Port States and Functions
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