Examkin

All practice questions

203 questions

All types1,987Multiple choice1,020Multiple select452Numeric18Matching229Ordering203Fill in the blank22Short answer43
Question 21Question →

A network administrator needs to create VLAN 85 named GUESTS on a Cisco Catalyst switch and configure interface GigabitEthernet0/2 as a static access port assigned to this VLAN, starting from Privileged EXEC mode (`Switch#`). In what sequence should the administrator execute the required Cisco IOS commands?

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct configuration order starts in Privileged EXEC mode with 'configure terminal', followed by 'vlan 85', 'name GUESTS', 'interface GigabitEthernet0/2', 'switchport mode access', and finally 'switchport access vlan 85'.
To successfully create a VLAN and configure an access port in Cisco IOS, commands must be executed in a specific hierarchical sequence. Starting at Privileged EXEC mode (`Switch#`), the user enters Global Configuration mode (`Switch(config)#`) using `configure terminal`. Next, VLAN 85 is instantiated with `vlan 85` into VLAN configuration mode (`Switch(config-vlan)#`), where `name GUESTS` sets the label. Moving back to Global Configuration mode context to select the target interface via `interface GigabitEthernet0/2` places the user in Interface Configuration mode (`Switch(config-if)#`). Here, `switchport mode access` disables dynamic trunk negotiation, and `switchport access vlan 85` assigns the port to the intended broadcast domain.

Step-by-Step Solution

1
Enter Global Configuration mode from Privileged EXEC mode.
Prompt changes to `Switch(config)#` after running `configure terminal`.
Global configuration mode is required to initiate VLAN creation and interface selection commands.
2
Create VLAN 85.
Prompt changes to `Switch(config-vlan)#` after issuing `vlan 85`.
Creates the VLAN ID in the Layer 2 database and opens VLAN configuration submode.
3
Assign the name GUESTS to the VLAN.
VLAN 85 is labeled with the name GUESTS upon executing `name GUESTS`.
Name configuration must take place inside the VLAN configuration submode.
4
Select interface GigabitEthernet0/2 for editing.
Prompt changes to `Switch(config-if)#` after issuing `interface GigabitEthernet0/2`.
Moves the CLI context into interface configuration mode for the specified target interface.
5
Set the administrative mode of the port to static access mode.
The port mode changes from dynamic negotiation to explicit access mode via `switchport mode access`.
Statically defining access mode ensures DTP negotiation does not form a trunk link unintentionally.
6
Assign the interface to VLAN 85.
Traffic on GigabitEthernet0/2 is tagged internally for VLAN 85 using `switchport access vlan 85`.
Associates untagged frames received on this access port with VLAN 85.

Key Concept

Cisco IOS CLI hierarchy for VLAN definition and static access port assignment
Estimated Time:1m 30s
Question 22Question →

An administrator connects a workstation to a Cisco Catalyst switch interface configured with standard IEEE 802.1D Spanning Tree Protocol (STP) where PortFast has NOT been enabled. Arrange the operational steps and port state transitions in the correct chronological sequence from the moment physical link status changes to up until the spanning-tree topology update process completes.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct chronological sequence for standard 802.1D STP port activation without PortFast is: 1) Initializing in the Blocking state to inspect incoming BPDUs; 2) Transitioning to the Listening state (15s) to elect spanning-tree roles via BPDU exchange without MAC learning; 3) Transitioning to the Learning state (15s) after the first Forward Delay to populate MAC address table entries; 4) Transitioning to the Forwarding state after the second Forward Delay to process user data frames; 5) Transmitting a Topology Change Notification (TCN) BPDU toward the Root Bridge due to the non-PortFast state transition.
The correct order reflects standard 802.1D STP convergence behavior: Blocking -> Listening (15s role election) -> Learning (15s MAC table population) -> Forwarding (active data transfer) -> TCN generation. Disabling or omitting PortFast on an access interface causes the full 30-second convergence delay and forces a network-wide MAC address table aging timer reduction via TCN BPDUs.

Step-by-Step Solution

1
Determine initial port state upon link initialization.
The port initializes in the Blocking state, dropping ingress traffic while listening for BPDUs.
Preventing layer 2 switching loops requires keeping the port from forwarding broadcast or unicast traffic prior to topology calculation.
2
Trace the first state transition during spanning-tree role determination.
The port enters the Listening state for 15 seconds (Forward Delay), sending and receiving BPDUs.
During Listening, the switch determines whether the port will become a Root Port, Designated Port, or return to Blocking, but does not learn MAC addresses.
3
Trace the second state transition following the first Forward Delay expiration.
The port transitions to the Learning state for 15 seconds (Forward Delay), inspecting frame source MAC addresses to populate the CAM table.
Learning MAC address locations prior to active frame forwarding minimizes unicast flooding once data transmission begins.
4
Identify the active operational state reached after timer expiration.
The port transitions to the Forwarding state, enabling bi-directional user payload frame transmission.
After passing two full Forward Delay timers (30 seconds total), the interface is confirmed loop-free and fully operational.
5
Determine post-transition notification behavior for non-PortFast ports.
The switch transmits a Topology Change Notification (TCN) BPDU out its Root Port toward the Root Bridge.
Because PortFast is not configured, transitioning a port to Forwarding triggers a topology change event, instructing switches in the domain to reduce MAC aging timers from 300 seconds to the Forward Delay timer (15 seconds).

Key Concept

IEEE 802.1D STP Port State Convergence Sequence and TCN Generation
Question 23Question →

A network administrator needs to manually configure an 802.1Q trunk on switch port GigabitEthernet0/1 and assign VLAN 99 as the untagged native VLAN. Place the Cisco IOS CLI configuration commands in the correct sequential order required to accomplish this task.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct order of configuration commands is: enter interface context ('interface GigabitEthernet0/1'), specify 802.1Q encapsulation ('switchport trunk encapsulation dot1q'), set operational mode to trunk ('switchport mode trunk'), and set native VLAN 99 ('switchport trunk native vlan 99').
To successfully establish an 802.1Q trunk link with a custom native VLAN on a Cisco switch interface, commands must be entered in hierarchical CLI order: first select the targeted interface ('interface GigabitEthernet0/1'), define the trunk encapsulation standard ('switchport trunk encapsulation dot1q'), force the link into trunking mode ('switchport mode trunk'), and finally designate the untagged native VLAN ('switchport trunk native vlan 99').

Step-by-Step Solution

1
Navigate to the targeted physical interface context.
Switch enters interface configuration mode for GigabitEthernet0/1.
Trunk configuration commands are applied directly under the specific switchport interface context.
2
Set the trunk encapsulation type to 802.1Q.
The interface uses 802.1Q frame tagging for VLAN multiplexing.
On Cisco Catalyst switches supporting legacy ISL and 802.1Q, encapsulation type must be explicitly specified before enabling trunk mode.
3
Enable static trunking mode.
The port transitions to a permanent 802.1Q trunking operational state.
The command 'switchport mode trunk' forces the interface into trunking mode.
4
Configure the native VLAN assignment.
VLAN 99 is assigned as the native (untagged) VLAN on the trunk.
Untagged frames sent and received over the 802.1Q trunk will be mapped to VLAN 99.

Key Concept

IEEE 802.1Q Trunk CLI Configuration Sequence
Question 24Question →

A network administrator needs to manually configure an 802.1Q trunk link on a switch port supporting multi-encapsulation according to security best practices. Place the Cisco IOS configuration commands in the correct execution sequence from initial interface selection to traffic pruning.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct configuration sequence is: 1) Enter interface context, 2) Define 802.1Q encapsulation, 3) Set switchport mode to trunk, 4) Reassign the native VLAN ID, and 5) Define allowed VLANs for traffic pruning.
The correct operational sequence begins with entering the interface configuration context. Next, on switches supporting multiple encapsulation protocols, 802.1Q encapsulation must be explicitly configured prior to setting the interface mode to trunk. Once the trunk state is active, security hardening steps follow: reassigning the untagged native VLAN away from VLAN 1, and finally filtering trunk traffic by restricting allowed VLANs.

Step-by-Step Solution

1
Select the target interswitch physical interface context.
Enters interface configuration prompt context.
CLI commands must target the specific interface designated for trunking.
2
Execute switchport trunk encapsulation dot1q.
Defines IEEE 802.1Q frame tagging for the port.
On legacy or multi-layer Catalyst switches, attempting switchport mode trunk before selecting encapsulation results in a CLI error.
3
Execute switchport mode trunk.
Forces interface into permanent trunking state.
Establishes trunk operation and stops unconditional access behavior.
4
Execute switchport trunk native vlan 99.
Changes untagged frame handling to VLAN 99.
Enhances security by avoiding the default native VLAN 1.
5
Execute switchport trunk allowed vlan 10,20,99.
Restricts broadcast/multicast forwarding to specified VLANs.
Implements traffic filtering and pruning across interswitch links.

Key Concept

Manual 802.1Q Trunk CLI Configuration Order
Question 25Question →

A network administrator configures a Cisco IOS router to synchronize its internal clock with an enterprise NTP server operating at Stratum 2. Arrange the operational steps in chronological order from initial packet transmission to the point where the router can act as a valid time source for downstream clients.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence of operations is: 1) The router sends an NTP client mode query (UDP port 123) to the server. 2) The router receives an NTP server mode response with Stratum 2 metadata. 3) The router computes round-trip delay, dispersion, and clock offset algorithms. 4) The router synchronizes its system clock and increments its operational stratum to Stratum 3. 5) The router begins answering incoming NTP queries from downstream clients.
NTP synchronization follows a strict sequential process: outbound UDP 123 request initiation, receipt of server time payload and stratum attributes, statistical filtering of offset and round-trip delay, local clock adjustment accompanied by stratum incrementing (N+1N+1), and finally responding to downstream client requests as a synchronized master time source.

Step-by-Step Solution

1
Initiate communication
Router sends an outbound NTP client packet over UDP port 123 to the NTP server address.
Synchronization starts when the client polls the server for time information.
2
Receive server response
Server replies with timestamp, stratum level (Stratum 2), and reference clock identification.
The server must supply its current time and stratum attributes back to the client.
3
Process NTP statistical filtering
Router calculates offset and network delay while filtering out jitter and invalid timestamps.
Packet delay and clock drift must be calculated before modifying the local system time.
4
Update local system time and stratum
Local clock synchronizes, and local stratum becomes Stratum 3 (2+12 + 1).
A synchronized NTP device always assumes a stratum number one unit higher than its synchronization source.
5
Serve downstream clients
Router processes and responds to NTP requests from local hosts.
Downstream devices can only receive valid, synchronized time after the router completes synchronization and establishes a valid stratum (< 16).

Key Concept

NTP Client-Server Initialization Sequence and Stratum Calculation
Question 26Question →

A network administrator needs to create VLAN 60 on a Cisco Catalyst switch, assign it the name PRINTERS, and configure interface GigabitEthernet0/14 as a static access port assigned to this VLAN. Place the Cisco IOS configuration commands in the correct sequential order starting from global configuration mode.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence begins by entering VLAN subconfiguration mode with 'vlan 60', setting the VLAN name with 'name PRINTERS', moving to the target interface subconfiguration mode using 'interface gigabitethernet0/14', setting the port operational mode to access with 'switchport mode access', and assigning the interface to the VLAN using 'switchport access vlan 60'.
The correct command order follows Cisco IOS context mode hierarchy: first entering VLAN subconfig mode with 'vlan 60' to create the VLAN, then configuring its name using 'name PRINTERS', next navigating to interface subconfig mode with 'interface gigabitethernet0/14', explicitly defining access mode using 'switchport mode access', and finally binding the port to the VLAN using 'switchport access vlan 60'.

Step-by-Step Solution

1
Enter VLAN configuration mode from global configuration mode
Prompt changes to Switch(config-vlan)#
VLAN 60 must be initialized in the switch VLAN database before naming or assigning interface membership.
2
Assign an administrative name to VLAN 60
VLAN 60 is assigned the name PRINTERS
The 'name' command is specific to VLAN subconfiguration mode and provides administrative identification for the broadcast domain.
3
Navigate to the specific interface configuration mode
Prompt changes to Switch(config-if)#
Interface parameters must be configured within interface subconfiguration mode.
4
Configure the interface mode as static access
Interface GigabitEthernet0/14 is defined as an access port
Executing 'switchport mode access' explicitly defines the port as non-trunking and disables dynamic trunk negotiation via DTP.
5
Assign the interface to VLAN 60
Interface GigabitEthernet0/14 becomes an active member of VLAN 60
The 'switchport access vlan 60' command associates untagged ingress/egress frames on GigabitEthernet0/14 with VLAN 60.

Key Concept

Cisco IOS command syntax and hierarchy for VLAN creation, naming, and access port assignment
Question 27Question →

Place the criteria evaluated during an OSPFv2 Designated Router (DR) election in order of precedence, starting with the highest priority evaluation criteria first.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct order of precedence for OSPFv2 DR/BDR election tie-breaking is: 1. Highest interface OSPF priority value (non-zero), 2. Highest manually configured OSPF Router ID, 3. Highest IP address among active loopback interfaces, 4. Highest IP address among active physical interfaces.
In OSPFv2 DR/BDR elections on broadcast or non-broadcast multiaccess networks, the selection process follows a strict precedence: interface priority is checked first (highest wins, while priority 0 is ineligible). If priorities tie, the OSPF Router ID determines the winner. The Router ID selection itself follows a deterministic hierarchy: explicit manual configuration via 'router-id' first, followed by the highest active loopback IP address, and finally the highest active physical interface IP address.

Step-by-Step Solution

1
Evaluate OSPF Interface Priority
Highest priority (1-255) wins. A priority of 0 excludes the router from becoming DR/BDR.
OSPF prioritizes administrator design intent via interface priority over IP address tie-breakers.
2
Evaluate Explicit Router ID
If priority values are equal, the router with the highest manually configured router-id value is selected.
Manual Router ID configuration overrides dynamically determined interface IP addresses.
3
Evaluate Active Loopback Interfaces
If no manual router ID exists, the highest IP address configured on an active loopback interface is chosen.
Loopback interfaces are logically stable and preferred over physical interfaces for RID determination.
4
Evaluate Active Physical Interfaces
If no loopback interfaces exist, the highest IP address configured on an active physical interface is used as the final tie-breaker.
Physical interface IPs serve as the final fallback for Router ID determination in OSPFv2.

Key Concept

OSPFv2 DR/BDR Election Precedence and Router ID Selection Criteria
Question 28Question →

A network engineer needs to manually configure an IEEE 802.1Q trunk link on a Cisco Catalyst switch interface (GigabitEthernet1/0/1) while following security best practices to disable Dynamic Trunking Protocol (DTP) and restrict active VLANs. What is the correct sequence of Cisco IOS CLI commands to accomplish this configuration on an interface supporting multi-protocol trunk encapsulation?

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct order of commands begins with entering interface configuration mode (`interface GigabitEthernet1/0/1`), setting 802.1Q encapsulation (`switchport trunk encapsulation dot1q`), enabling trunk mode statically (`switchport mode trunk`), turning off DTP negotiation (`switchport nonegotiate`), and finally restricting the allowed VLAN list (`switchport trunk allowed vlan 10,20,30`).
The correct sequence respects Cisco IOS CLI syntax dependency rules: interface mode must be accessed first, followed by defining 802.1Q encapsulation prior to setting static trunk mode. Static trunking must be active before DTP frame transmission can be disabled with `switchport nonegotiate`, and allowed VLAN parameters are applied to restrict trunk traffic.

Step-by-Step Solution

1
Enter interface configuration mode
Access the interface context for GigabitEthernet1/0/1.
CLI commands affecting a specific switchport can only be applied within interface configuration mode.
2
Specify 802.1Q encapsulation protocol
Set trunk encapsulation type to dot1q.
On multi-encapsulation Catalyst switches, Cisco IOS requires explicit encapsulation definition before allowing the port mode to be changed to trunk.
3
Set port mode to static trunking
Force port state into unconditional trunk mode.
Static trunk mode disables dynamic negotiation behavior requirement and prepares the port for non-negotiation.
4
Disable Dynamic Trunking Protocol (DTP)
Stop sending DTP frames out of the interface.
The `switchport nonegotiate` command prevents DTP negotiation but is rejected by Cisco IOS if the interface is still set to dynamic auto or dynamic desirable.
5
Configure allowed VLAN list
Restrict VLAN traffic traversing the trunk to VLANs 10, 20, and 30.
Prunes unauthorized VLAN traffic from crossing the interswitch trunk link as part of security hardening.

Key Concept

Cisco IOS CLI trunk configuration sequence and DTP operational state requirements for 802.1Q trunking
Estimated Time:1m 30s
Question 29Question →

A Cisco Catalyst switch receives an Ethernet frame on interface FastEthernet0/1. The frame contains a source MAC address that does not currently exist in the MAC address table, and a destination MAC address that is already registered to interface FastEthernet0/4. In what correct sequential order does the switch perform its internal frame processing and forwarding tasks?

Drag items to arrange them in the correct order

Show answer & explanation

Answer

1. Receive the Ethernet frame on interface FastEthernet0/1 and inspect the Layer 2 header for source and destination MAC addresses.
2. Check the MAC address table for the source MAC address and create a dynamic entry associating it with FastEthernet0/1.
3. Perform a lookup in the MAC address table using the destination MAC address to identify the associated egress port.
4. Forward the unicast frame exclusively out interface FastEthernet0/4 without flooding.
When a switch receives a frame, it sequentially executes two main phases: MAC learning followed by frame forwarding. First, it extracts the header information on the ingress port. Second, it inspects the source MAC address; if missing from the MAC address table, it records a dynamic entry associating the source MAC with the receiving port and VLAN. Third, it checks the destination MAC address against its MAC address table. Fourth, because a matching entry exists for FastEthernet0/4, the switch forwards the frame directly out that single interface without flooding.

Step-by-Step Solution

1
Frame Ingress Inspection
Source and destination MAC address fields are read from the incoming Ethernet frame header.
The switch must inspect the frame header on port FastEthernet0/1 to extract the Layer 2 addressing information.
2
Source MAC Learning
A new entry is added to the MAC address table mapping the source MAC address to interface FastEthernet0/1.
Layer 2 switches learn source MAC addresses upon ingress prior to making any forwarding decisions.
3
Destination Address Table Query
The destination MAC address is matched to existing entry for interface FastEthernet0/4.
The switch inspects its Content Addressable Memory (CAM) table to determine where to direct the frame.
4
Known Unicast Egress Forwarding
The frame is transmitted directly out interface FastEthernet0/4.
Matching a known destination MAC address triggers point-to-point unicast forwarding instead of unknown unicast flooding.

Key Concept

Layer 2 frame processing pipeline: MAC learning occurs on ingress before destination lookup and forwarding.
Question 30Question →

A network administrator needs to manually configure a switch port as an IEEE 802.1Q trunk link and limit the traffic traversing the link to specific VLANs. What is the correct sequence of CLI configuration commands to perform this setup on a Cisco Catalyst switch interface from first to last?

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct order of configuration commands is: 1) Enter interface configuration mode (interface GigabitEthernet0/1), 2) Set encapsulation to dot1q (switchport trunk encapsulation dot1q), 3) Set mode to trunk (switchport mode trunk), and 4) Specify allowed VLANs (switchport trunk allowed vlan 10,20).
The proper administrative sequence requires entering the target interface configuration mode first, setting the 802.1Q encapsulation protocol second, forcing the port into permanent trunking mode third, and finally defining the list of allowed VLANs to prune unwanted traffic.

Step-by-Step Solution

1
Navigate to the targeted physical interface context.
Enters interface configuration sub-mode prompt Switch(config-if)#.
Interface parameters can only be altered from within interface configuration sub-mode.
2
Define 802.1Q encapsulation.
Configures IEEE 802.1Q frame tagging as the trunking method.
Cisco IOS switches supporting both ISL and 802.1Q reject the 'switchport mode trunk' command until encapsulation is explicitly defined.
3
Configure static trunk mode.
Forces the interface into an active trunking operational state.
This command turns off dynamic port mode negotiation and forces the port into a permanent trunking state.
4
Apply allowed VLAN list filtering.
Limits trunk traffic to VLAN 10 and VLAN 20.
Pruning unneeded VLANs improves security and reduces broadcast traffic across switch links.

Key Concept

IEEE 802.1Q Trunk Interface CLI Configuration Workflow
Question 31Question →

A Cisco Catalyst switch receives an untagged Ethernet frame on an interface configured as an 802.1Q trunk port. Place the operational steps performed by the switch in the correct order from ingress frame arrival to egress transmission.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence is: (1) Frame reception on 802.1Q trunk, (2) Internal classification into ingress native VLAN, (3) Ingress trunk allowed VLAN list verification, (4) MAC address table lookup within native VLAN context, and (5) Egress transmission untagged on matching native VLAN trunk.
When an untagged frame is received on an 802.1Q trunk port, the switch first accepts the frame and assigns it internally to the interface's native VLAN. It then validates whether that native VLAN is permitted according to the trunk's allowed VLAN configuration. Next, it performs a Layer 2 MAC table lookup restricted to that native VLAN's broadcast domain to select the egress port. Finally, when transmitting out another trunk port configured with the same native VLAN, the switch leaves the frame untagged according to 802.1Q specification.

Step-by-Step Solution

1
Identify the ingress frame state upon arrival.
The frame arrives on the 802.1Q trunk interface lacking a 4-byte 802.1Q VLAN header.
802.1Q trunks expect untagged frames to belong to the designated native VLAN.
2
Map untagged ingress traffic to the port's native VLAN.
The switch internal ASIC assigns the frame to the configured native VLAN ID of the receiving trunk port.
All frames moving through a Catalyst switch fabric must be associated with a specific VLAN domain.
3
Check interface trunk filtering rules (allowed VLAN list).
The switch confirms that the native VLAN ID is present in the `switchport trunk allowed vlan` filter for that interface.
If the native VLAN was explicitly removed from the allowed list, the switch would drop the frame at ingress.
4
Determine the Layer 2 egress destination.
The switch queries its MAC address table within the scope of the assigned native VLAN.
VLAN isolation requires that MAC lookups occur strictly within the MAC table instance dedicated to that specific VLAN.
5
Apply egress 802.1Q tagging rules prior to transmission.
The frame is forwarded out the destination trunk port untagged because its VLAN matches the destination port's configured native VLAN.
Standard IEEE 802.1Q behavior specifies that frames belonging to a trunk's native VLAN are transmitted across the link without an 802.1Q tag header.

Key Concept

IEEE 802.1Q Native VLAN Ingress Classification, Filtering, and Egress Tagging Lifecycle
Estimated Time:2m 0s
Question 32Question →

A Cisco switch receives an untagged Ethernet frame on an IEEE 802.1Q trunk link and forwards it out another 802.1Q trunk link. Arrange the operational steps in the correct order from initial frame arrival to final frame transmission.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct operational sequence begins with the arrival of an untagged Ethernet frame on an 802.1Q trunk port, followed by internal mapping to the ingress port's native VLAN, executing a MAC address table lookup within that native VLAN, and finally transmitting the frame untagged out an egress trunk configured with a matching native VLAN.
IEEE 802.1Q trunks handle untagged traffic by implicitly classifying ingress frames into the configured native VLAN. The switch uses that native VLAN's MAC address table for forwarding decisions and sends the frame out an egress trunk untagged if the egress interface shares the same native VLAN configuration.

Step-by-Step Solution

1
Identify ingress frame format
The switch identifies that the incoming frame lacks a 4-byte IEEE 802.1Q tag header.
Trunk ports process both tagged and untagged frames depending on whether traffic belongs to tagged VLANs or the native VLAN.
2
Classify frame to native VLAN
The frame is internally tagged/associated with the ingress port's native VLAN ID.
IEEE 802.1Q specification requires untagged frames traversing a trunk to be implicitly assigned to the native VLAN.
3
Execute Layer 2 forwarding lookup
The switch consults the MAC address table for the destination address within the native VLAN domain.
VLANs maintain isolated broadcast domains and separate MAC lookup tables to prevent cross-VLAN frame leakage.
4
Evaluate egress tagging behavior
The frame is forwarded across the egress trunk port without inserting an 802.1Q header tag.
To maintain compatibility, 802.1Q does not tag frames belonging to the native VLAN when sending them over trunk links.

Key Concept

IEEE 802.1Q Native VLAN Ingress and Egress Processing Mechanics
Question 33Question →

A network administrator connects two Cisco Catalyst switches via their GigabitEthernet0/1 interfaces. Switch-A is configured with `switchport mode dynamic desirable`, while Switch-B remains in its default `dynamic auto` mode. What is the correct chronological sequence of operational events during Dynamic Trunking Protocol (DTP) negotiation to establish an IEEE 802.1Q trunk link?

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence is: Switch-A transmits a DTP frame requesting a trunk, Switch-B receives and parses the DTP frame, Switch-B transmits a DTP acknowledgment frame, both switches agree upon IEEE 802.1Q encapsulation, and finally both switch interfaces transition to the operational trunk state.
The correct order follows the DTP state machine negotiation flow. A port in `dynamic desirable` mode actively sends DTP request frames to its link partner. The neighboring port in `dynamic auto` mode receives and processes this request, responding with a DTP acknowledgment frame to consent to trunking. Following parameter exchange, both switches negotiate the trunk encapsulation (IEEE 802.1Q) and finally transition both interface operational states to trunking.

Step-by-Step Solution

1
Identify the initiating interface state and behavior
Switch-A (`dynamic desirable`) actively sends DTP negotiation frames to initiate trunking.
Interfaces in `dynamic desirable` mode actively attempt to convert the link to a trunk.
2
Determine the receiving interface processing
Switch-B (`dynamic auto`) receives the request and evaluates parameters.
Interfaces in `dynamic auto` mode do not initiate DTP requests but respond to incoming requests.
3
Trace the protocol response and handshake
Switch-B sends a DTP response agreeing to form a trunk link.
A `dynamic auto` port agrees to become a trunk when requested by a `dynamic desirable` port.
4
Resolve encapsulation negotiation
Both switches negotiate and agree on 802.1Q encapsulation.
Trunking encapsulation must be determined prior to bringing up the operational trunking state.
5
Confirm operational state transition
Both ports transition to operational trunking mode.
Once negotiation handshakes and parameters match, the link operational mode becomes trunk.

Key Concept

Dynamic Trunking Protocol (DTP) negotiation flow between dynamic desirable and dynamic auto interface modes in IEEE 802.1Q trunking.
Estimated Time:2m 0s
Question 34Question →

A host in VLAN 20 sends an Ethernet frame to another host in VLAN 20 located on a remote switch across an IEEE 802.1Q trunk link. What is the correct chronological sequence of events for processing and forwarding this frame from the source access port to the destination access port?

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct chronological sequence begins with Switch 1 receiving the untagged frame on an access port, inserting a 4-byte 802.1Q tag for VLAN 20, transmitting the tagged frame over the trunk, Switch 2 receiving and identifying the tagged frame, Switch 2 stripping the 802.1Q header, and finally delivering the untagged frame to the destination host on the access port.
The correct sequence follows standard IEEE 802.1Q trunking operations: frames enter an access port untagged, are tagged with a 4-byte header containing the VLAN ID when forwarded out a trunk port for non-native VLANs, travel across the link, are read and stripped of the tag by the remote switch, and are finally delivered untagged to the destination host on an access port in the same VLAN.

Step-by-Step Solution

1
Identify frame ingress at the source switch
The source switch accepts an untagged frame on a standard VLAN 20 access port.
End-user hosts send standard Ethernet frames without 802.1Q tags.
2
Apply 802.1Q tagging prior to trunk egress
A 4-byte 802.1Q tag with VLAN ID 20 is inserted into the Ethernet header.
Trunk links require frame tagging to distinguish traffic belonging to non-native VLANs across switches.
3
Transmit the tagged frame across the trunk
The frame travels over the physical interswitch link.
The frame carries the VLAN 20 identifier across the shared trunk interface.
4
Process frame ingress at the receiving switch
Switch 2 reads the 802.1Q tag to determine the target VLAN.
The receiving switch relies on the tag to route the frame internally within the correct VLAN context.
5
De-encapsulate the 802.1Q frame
The 4-byte 802.1Q header is stripped from the frame.
Standard access ports must not send tagged frames to end hosts that do not support 802.1Q tagging.
6
Forward untagged frame to destination host
The original frame is delivered out the destination VLAN 20 access port.
The destination host receives standard Ethernet traffic identical to what was originally transmitted.

Key Concept

802.1Q Frame Tagging and Trunk Processing Lifecycle
Estimated Time:1m 0s
Question 35Question →

An access port on a Cisco switch running IEEE 802.1D Spanning Tree Protocol (STP) without PortFast enabled is connected to a workstation and experiences a link-up event. Arrange the operational STP port states in the exact sequential order that the interface undergoes from initial link activation until it actively processes and forwards user data traffic.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct operational sequence of 802.1D STP port states from link activation to active forwarding is: Blocking state, Listening state, Learning state, and Forwarding state.
IEEE 802.1D Spanning Tree Protocol transitions non-PortFast interfaces through a mandatory four-stage sequence: Blocking (loop prevention), Listening (BPDU exchange and port role determination), Learning (building MAC tables), and Forwarding (active user frame transmission).

Step-by-Step Solution

1
Identify the initial default safety state upon link bring-up in classic IEEE 802.1D STP.
The port enters the Blocking state immediately upon physical link detection.
Default 802.1D STP behavior forces a non-PortFast interface into Blocking to prevent immediate Layer 2 loop creation.
2
Determine the state where active BPDU negotiation and role determination occur.
The port transitions from Blocking to the Listening state for a duration of 15 seconds.
In Listening, the switch transmits and processes BPDUs to determine active topology roles, while suppressing MAC table learning and user data frame forwarding.
3
Identify the state dedicated to populating switch address tables prior to data forwarding.
The port transitions from Listening to the Learning state for a duration of 15 seconds.
In Learning, the port populates its MAC address table from incoming frame source MACs to prevent unnecessary unicast flooding when data forwarding starts.
4
Identify the final fully functional operational state.
The port transitions from Learning into the Forwarding state.
After the total 30-second convergence delay (2 x 15-second Forward Delay timers) completes without topology conflicts, the interface begins normal frame forwarding.

Key Concept

IEEE 802.1D STP Port State Transition Sequence
Question 36Question →

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.

Drag items to arrange them in the correct order

Show answer & explanation

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 37Question →

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.

Drag items to arrange them in the correct order

Show answer & explanation

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 38Question →

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.

Drag items to arrange them in the correct order

Show answer & explanation

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 39Question →

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.

Drag items to arrange them in the correct order

Show answer & explanation

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 40Question →

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.

Drag items to arrange them in the correct order

Show answer & explanation

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
PreviousPage 2 / 11Next
All practice questions — Cisco CCNA | Examkin