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Soru 121Soru →

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

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

Adım Adım Çözüm

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

Anahtar Kavram

Layer 3 LACP EtherChannel CLI configuration order
Tahmini Süre:1m 30s
Soru 122Soru →

When a Cisco router processes an ingress IPv4 packet destined for a remote network, it executes a deterministic evaluation sequence to determine the forwarding path and transmit the frame. Place the operational steps in the correct chronological order from packet ingress to egress frame encapsulation.

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The correct evaluation sequence begins with extracting the destination IPv4 address, followed by performing Longest Prefix Match lookup in the routing table, evaluating protocol metrics for equal prefix ties, resolving the next-hop IP and egress interface, and finally resolving ARP to rewrite Layer 2 headers for frame transmission.
Router forwarding logic follows a mandatory sequence: packet header inspection, route selection via Longest Prefix Match (LPM), tie-breaking via metric for matching prefix length, identification of exit interface/next-hop IP, and Layer 2 frame encapsulation via ARP lookup.

Adım Adım Çözüm

1
Parse packet header
Destination IPv4 address identified
The router must inspect the Layer 3 header to determine where the packet is destined.
2
Perform Longest Prefix Match (LPM)
Candidate route with most specific subnet mask selected
Longest Prefix Match is the absolute primary rule in IP route selection.
3
Evaluate protocol metric
Single best route or equal-cost paths selected
If identical routes exist within a single protocol source, metric breaks the tie.
4
Determine egress parameters
Next-hop IP and outbound interface bound
The router maps the selected routing entry to its configured exit interface and next hop.
5
Encapsulate and transmit frame
Layer 2 MAC rewrite complete and bits transmitted
Address Resolution Protocol (ARP) supplies the next-hop MAC address to build the new data link layer frame.

Anahtar Kavram

Router Forwarding Decision Logic
Soru 123Soru →

An engineer connects a new host to interface FastEthernet0/12 on a Cisco Catalyst switch. The host immediately sends a unicast Ethernet frame intended for a server whose MAC address is already dynamically learned on interface FastEthernet0/18. Arrange the operational steps in the exact chronological order that the switch executes upon receiving this frame.

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The correct operational sequence begins with frame reception on FastEthernet0/12, followed by source MAC address learning, destination MAC lookup in the table, identifying the egress port match on FastEthernet0/18, and finally unicast forwarding out FastEthernet0/18.
Layer 2 switch operation dictates a strict sequence of events upon frame arrival: frame ingress occurs first, followed immediately by source MAC address learning (adding or updating the source MAC and interface association in the MAC address table). Next, the switch performs a table lookup for the destination MAC address, identifies the matching egress interface (FastEthernet0/18), and lastly forwards the unicast frame directly out that specific interface.

Adım Adım Çözüm

1
Identify the ingress port event.
The switch receives the raw frame on FastEthernet0/12.
Frame processing cannot occur until the physical interface receives and buffers the frame.
2
Perform ingress source MAC learning.
The switch associates the frame's source MAC address with interface FastEthernet0/12 in its Layer 2 MAC address table.
Cisco switches always process source MAC learning prior to destination forwarding logic.
3
Perform destination MAC table lookup.
The switch checks its MAC address table for the frame's destination address.
The destination MAC determines whether the frame will be unicast forwarded, flooded, or filtered.
4
Evaluate the table lookup result.
An existing mapping points to interface FastEthernet0/18.
Since the server's MAC was previously learned, the destination lookup succeeds.
5
Execute frame forwarding.
The switch transmits the frame solely out interface FastEthernet0/18.
Known unicast frames are forwarded strictly to the matching egress port, preventing unnecessary broadcast domain traffic.

Anahtar Kavram

L2 Switch Ingress Processing, MAC Address Learning, and Known Unicast Forwarding
Soru 124Soru →

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

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

Adım Adım Çözüm

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

Anahtar Kavram

Rapid PVST+ Root Port Selection Tie-Breaker Order
Tahmini Süre:1m 15s
Soru 125Soru →

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

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

Adım Adım Çözüm

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

Anahtar Kavram

802.1D Spanning Tree Protocol Port State Transition Sequence
Soru 126Soru →

A network administrator needs to manually configure a backup floating static route on a Cisco IOS router. Arrange the following syntax elements in the correct sequential order from left to right to construct a valid Cisco IOS floating static route command.

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The correct sequence to construct the command is: ip route 172.16.1.0 255.255.255.0 10.1.1.2 130.
The correct order follows the standard Cisco IOS static route syntax: 'ip route <destination-prefix> <subnet-mask> {ip-address | exit-interface} [distance]'. The command starts with 'ip route', followed by the target destination network (172.16.1.0), the subnet mask (255.255.255.0), the next-hop address (10.1.1.2), and finally the optional Administrative Distance value (130).

Adım Adım Çözüm

1
Begin with the global configuration command keyword.
Specifies 'ip route' at the beginning of the command string.
Cisco IOS requires the 'ip route' command keyword to define a static routing entry.
2
Append the destination network address followed by its subnet mask.
Adds '172.16.1.0 255.255.255.0'.
The router needs the target IP subnet prefix and corresponding subnet mask to evaluate match length in the routing table.
3
Specify the next-hop IP address or local exit interface.
Adds '10.1.1.2'.
Defines the forwarding destination or gateway to reach the target network.
4
Append the optional Administrative Distance value at the end.
Adds '130'.
Assigning an Administrative Distance higher than the primary route (e.g., OSPF AD 110) creates a floating static route that remains inactive until the primary route drops.

Anahtar Kavram

Cisco IOS IPv4 static route CLI syntax structure and floating static route parameter placement.
Soru 127Soru →

A Cisco router receives an IPv4 packet destined for a remote host and evaluates its routing table containing multiple routes from different sources. Place the steps of the router's forwarding decision logic in the correct order from first to last.

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The correct sequence of router forwarding decision logic from first to last is: 1) Select the route with the longest prefix match; 2) Compare Administrative Distance if prefix lengths are identical; 3) Compare metric values if AD and prefix lengths are identical; 4) Forward the packet using the selected route's exit interface and next hop.
When a Cisco router makes a forwarding decision, it follows a strict hierarchical evaluation sequence. First, it identifies all routes in the routing table that match the destination IPv4 address and selects the route with the longest prefix match (most specific subnet mask). Second, if there are multiple matching routes with identical prefix lengths, it evaluates Administrative Distance (AD) to pick the route from the most trustworthy routing protocol. Third, if multiple routes share identical prefix lengths and AD values, it compares the metric (path cost) to choose the lowest metric route. Finally, once the single best route is determined, the router forwards the packet out the associated exit interface.

Adım Adım Çözüm

1
Evaluate Longest Prefix Match (LPM)
The router identifies all routes matching the destination IP address and prioritizes the route with the longest prefix length (most specific subnet mask).
LPM always takes absolute precedence over Administrative Distance and Metric.
2
Compare Administrative Distance (AD)
If multiple routes have the exact same prefix length, the router selects the route from the routing source with the lowest AD.
Administrative Distance measures the believability and trustworthiness of the routing source.
3
Compare Metric
If AD and prefix length are identical (e.g., multiple routes learned via the same dynamic routing protocol), the route with the lowest metric is selected.
Metric measures path cost within a single routing protocol.
4
Forward the Packet
The router encapsulates the packet and sends it via the selected route's exit interface and next-hop IP address.
Once the best route determination is complete, the data plane handles packet transmission.

Anahtar Kavram

Router Forwarding Decision Logic Precedence (Longest Prefix Match > Administrative Distance > Metric)
Soru 128Soru →

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

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

Adım Adım Çözüm

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

Anahtar Kavram

WLC GUI WLAN Creation and Client Connectivity Workflow
Tahmini Süre:1m 30s
Soru 129Soru →

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

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

Adım Adım Çözüm

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

Anahtar Kavram

WLAN Infrastructure LAG and Switch EtherChannel Implementation Sequence
Tahmini Süre:2m 0s
Soru 130Soru →

A Cisco router receives an IPv4 packet destined for a remote host. Place the sequential steps of the router's forwarding decision logic in the correct order from first to last.

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The correct sequence begins with extracting the packet's destination IP address, applying Longest Prefix Match to identify candidate routes, comparing Administrative Distance for equal-length prefix ties, comparing metric/cost for intra-protocol ties, and completing Layer 2 encapsulation for egress transmission.
When forwarding an IP packet, a Cisco router follows a precise hierarchy: it extracts the destination address, evaluates all matching routing table entries to find the Longest Prefix Match (most specific subnet mask), breaks ties between different routing protocols using Administrative Distance (lowest wins), breaks ties within the same protocol using Metric/Cost (lowest wins), and finally resolves the Layer 2 next-hop rewrite for frame transmission.

Adım Adım Çözüm

1
Extract Destination IPv4 Address
The destination IP address is identified from the incoming IPv4 packet header.
The destination address is required to query the routing table.
2
Apply Longest Prefix Match (LPM)
Routes with the longest/most specific matching prefix length (subnet mask) are isolated.
LPM is the primary rule of IP routing decision logic and overrides Administrative Distance and Metric.
3
Evaluate Administrative Distance (AD)
If candidate routes have identical prefix lengths, the route with the lowest AD is selected.
AD determines the believability of different routing sources.
4
Evaluate Protocol Metric / Cost
If candidate routes are from the same routing protocol and share equal prefix lengths, the path with the lowest metric is chosen.
Metric measures path efficiency within a single routing protocol.
5
Encapsulate and Forward Frame
The router looks up the next-hop IP in the ARP table, constructs a new Layer 2 header, and sends the frame out the exit interface.
Layer 2 rewrite completes the packet forwarding action at the data plane.

Anahtar Kavram

Router Forwarding Decision Logic Sequence
Soru 131Soru →

A Cisco router receives an IPv4 packet on an ingress interface destined for a remote destination host. In what exact sequence does the router execute its internal forwarding decision and frame processing logic from packet arrival to egress transmission?

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The correct sequential order of the Cisco router forwarding decision logic is: First, de-encapsulate the frame, verify IP header integrity, and extract the destination IPv4 address. Second, search the IPv4 routing table for all matching prefix entries. Third, select the single best route entry strictly using Longest Prefix Match (LPM). Fourth, identify the egress exit interface and next-hop IPv4 address from the selected route. Fifth, resolve the next-hop Layer 2 MAC address, decrement TTL, rewrite the Layer 2 header, and transmit the frame.
The correct operational sequence begins when an IPv4 packet arrives at a router interface. The router first strips the ingress Layer 2 header, validates the IP checksum/TTL, and extracts the destination IP address. Next, it queries the IPv4 routing table for all matching subnets. It applies Longest Prefix Match (LPM) precedence to choose the candidate route with the longest subnet mask. After selecting the winning route, it extracts the next-hop IP address and outbound interface. Finally, it uses ARP to find the next-hop MAC address, decrements the TTL by 1, encapsulates the packet in a new Layer 2 header, and transmits it out the exit interface.

Adım Adım Çözüm

1
Frame De-encapsulation and Header Validation
Layer 2 frame header is stripped, and the destination IPv4 address is extracted from the IPv4 header.
The router must inspect the Layer 3 destination header to determine where the packet needs to be routed.
2
Routing Table Candidate Search
A set of candidate subnet routes that cover the destination IPv4 address is identified.
All active routes in the Routing Information Base (RIB) or Forwarding Information Base (FIB) are scanned for binary subnet matching.
3
Longest Prefix Match (LPM) Evaluation
The route with the highest number of matching network bits (longest prefix mask) is selected.
Longest Prefix Match is the absolute primary criteria for route selection in IP routing, overriding Administrative Distance and routing metrics.
4
Forwarding Path Extraction
The destination next-hop IPv4 address and outgoing physical/logical exit interface are determined.
The router needs the exact forwarding instructions specified inside the winning routing table entry.
5
Layer 2 Encapsulation and Egress Transmission
The packet TTL is decremented, ARP cache provides the next-hop MAC address, a new Layer 2 frame is encapsulated, and the frame is transmitted.
The router must rewrite the Layer 2 header for the next-hop broadcast domain before transmitting the packet on the wire.

Anahtar Kavram

Router Forwarding Decision Logic and Longest Prefix Match
Soru 132Soru →

A network host sends a unicast Ethernet frame to a Layer 2 switch. The source MAC address of the frame is not currently present in the switch's MAC address table, but the destination MAC address is already mapped to an active interface. In what sequence does the switch perform operations to process and forward this frame? Arrange the switch operations in the correct chronological order from first to last.

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The correct sequence of switch operations is: receiving the frame on the ingress interface, examining and recording the source MAC address in the MAC address table, looking up the destination MAC address in the table, identifying the corresponding egress interface, and forwarding the unicast frame directly out that egress interface.
When an Ethernet frame arrives on a switch port, the switch first learns or updates the mapping of the frame's source MAC address to the ingress interface in its MAC address table. Next, it performs a lookup for the destination MAC address. Because the destination MAC address is already known, the switch identifies the single mapped egress interface and forwards the frame directly out that port without flooding.

Adım Adım Çözüm

1
Frame Ingress
The Ethernet frame enters the switch port buffer.
Layer 2 processing begins as soon as the physical frame is received on an interface.
2
Source MAC Learning
The unknown source MAC address is mapped to the ingress port in the MAC address table.
Switches continuously build their MAC address table by examining the source MAC address of every incoming frame.
3
Destination MAC Lookup
The switch searches its MAC address table for the destination MAC address.
Forwarding decisions are determined by comparing the destination MAC address against existing table entries.
4
Egress Port Selection
The switch identifies the target egress port linked to the destination MAC address.
A valid table match maps the destination MAC address directly to a specific physical or logical interface.
5
Unicast Forwarding
The frame is transmitted out the target egress port.
Known unicast frames are forwarded strictly out the designated interface rather than being flooded out all ports.

Anahtar Kavram

Layer 2 MAC Address Table Learning and Known Unicast Forwarding Logic
Soru 133Soru →

A Cisco IOS router (R1) is configured with three routes for the destination prefix 192.168.10.0/24192.168.10.0/24: a primary static route (`ip route 192.168.10.0 255.255.255.0 10.0.12.2`), an active OSPFv2 dynamic route (Administrative Distance 110 via 10.0.14.210.0.14.2), and a backup floating static route (`ip route 192.168.10.0 255.255.255.0 10.0.13.2 120`). Place the control plane and data plane events in the correct chronological sequence starting immediately after the physical interface connected to 10.0.12.210.0.12.2 fails.

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The correct sequence of events is: Interface link failure → Primary static route RIB withdrawal → AD evaluation selecting OSPF over floating static → FIB table update → Forwarding of packets via the OSPF path.
When an active egress interface fails, Cisco IOS immediately removes the connected static route from the Routing Information Base (RIB). The router then re-evaluates all available candidate routes for the exact destination prefix (192.168.10.0/24192.168.10.0/24). Because the prefix lengths are identical, the router compares Administrative Distance (AD). OSPF (AD 110) is preferred over the floating static route (AD 120). Once the RIB settles on the OSPF path, the control plane programs the Forwarding Information Base (FIB), and data plane traffic resumes forwarding out the OSPF next-hop.

Adım Adım Çözüm

1
Identify link status change
Interface going down invalidates directly associated static route next-hops.
Cisco IOS requires an active interface to keep static routes active in the RIB.
2
Withdraw primary static route from RIB
Primary static route with Administrative Distance 1 is purged.
Unreachable next-hop interfaces trigger route removal.
3
Compare Administrative Distance of remaining matching prefixes
OSPF route (AD 110) is selected instead of the floating static route (AD 120).
When prefix lengths match exactly (192.168.10.0/24192.168.10.0/24), the route with the lowest Administrative Distance is installed.
4
Update Cisco Express Forwarding (CEF) FIB hardware tables
FIB updates pointer for 192.168.10.0/24192.168.10.0/24 to point to 10.0.14.210.0.14.2.
RIB modifications must sync to the FIB for hardware-accelerated forwarding.
5
Process data plane traffic
Packets targeting 192.168.10.50192.168.10.50 switch path to 10.0.14.210.0.14.2.
Subsequent ingress traffic matches the newly installed FIB lookup entry.

Anahtar Kavram

IPv4 Static Route RIB Lifecycle, Floating Static Administrative Distance Calibration, and CEF FIB Convergence
Soru 134Soru →

A network engineer is analyzing the rapid convergence mechanism of Rapid PVST+ (IEEE 802.1w) on a point-to-point link between two Cisco Catalyst switches. Place the steps of the Rapid PVST+ Proposal-Agreement handshake sequence in the correct chronological order from first event to final event.

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Cevap

The correct order of events in the Rapid PVST+ Proposal-Agreement handshake sequence is: 1) The upstream switch transmits a BPDU with the Proposal bit set. 2) The downstream switch selects the port as its new Root Port and blocks non-edge Designated Ports (synchronization). 3) The downstream switch sends an Agreement BPDU back to the upstream switch. 4) The upstream switch immediately transitions its Designated Port to the Forwarding state.
Rapid PVST+ (IEEE 802.1w) achieves rapid convergence on point-to-point links through an active handshake sequence between switch ports. First, the upstream switch transmits a proposal BPDU on its Designated Port. Second, the downstream switch recognizes the superior BPDU, adopts the receiving interface as its Root Port, and blocks all non-edge Designated Ports to synchronize the switch topology. Third, once synchronized, the downstream switch responds with an Agreement BPDU on its new Root Port. Finally, the upstream switch receives this agreement and immediately transitions its Designated Port to the Forwarding state without waiting for legacy forward delay timers.

Adım Adım Çözüm

1
Identify the initial proposal transmission.
The upstream switch sends a BPDU with the Proposal bit set.
Rapid PVST+ uses explicit handshake messages rather than timer-based transitions on point-to-point links. The process starts when a switch sends a Proposal BPDU out of a Designated Port.
2
Determine the downstream switch state synchronization.
The downstream switch selects the port as Root Port and puts non-edge Designated Ports into Discarding.
To prevent transient Layer 2 loops while agreeing to the new topology, the downstream switch performs synchronization by isolating (discarding on) all non-edge Designated ports.
3
Identify the agreement response mechanism.
The downstream switch sends an Agreement BPDU back on its new Root Port.
Once all interfaces are verified synchronous, the downstream switch confirms loop-free readiness by transmitting an Agreement BPDU.
4
Determine the final port state transition.
The upstream switch transitions its Designated Port directly into Forwarding.
Upon receiving the Agreement BPDU, the upstream switch immediately moves its Designated Port to Forwarding without waiting for traditional 15-second Listening/Learning timers.

Anahtar Kavram

Rapid PVST+ Proposal-Agreement Handshake Convergence
Soru 135Soru →

A Cisco router receives an IPv4 packet destined for host 192.168.10.45192.168.10.45, which matches a static route configured strictly with a next-hop IP address (10.0.0.210.0.0.2) rather than an exit interface. Arrange the operational steps in the exact sequence the router executes to process, resolve, and forward this packet.

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Cevap

The correct sequence of router operation steps is: Extract the destination IPv4 address (192.168.10.45192.168.10.45), search the IPv4 RIB using Longest Prefix Match, identify the next-hop IPv4 address (10.0.0.210.0.0.2), perform a recursive lookup to resolve the exit interface, and consult the ARP table to encapsulate and transmit the packet.
When a Cisco router receives an IPv4 packet, it extracts the destination IP address from the packet header (192.168.10.45192.168.10.45). Next, it evaluates its routing table (RIB) using Longest Prefix Match (LPM) to find the most specific route entry. Upon finding the static route, it identifies that the destination is reached via next-hop IP 10.0.0.210.0.0.2. Because the static route was configured without specifying an egress interface, the router must perform a recursive lookup in the routing table to determine which directly connected interface reaches 10.0.0.210.0.0.2. Once the exit interface is resolved, the router queries its ARP cache to map 10.0.0.210.0.0.2 to a Layer 2 MAC address, re-encapsulates the packet into a new Layer 2 frame, and transmits it out the interface.

Adım Adım Çözüm

1
Packet Ingress and Header Parsing
Destination IPv4 address 192.168.10.45192.168.10.45 is extracted.
The router needs the destination IPv4 address to perform a routing lookup.
2
RIB Query via Longest Prefix Match
The static route entry best matching 192.168.10.45192.168.10.45 is selected.
Routing decisions in Cisco IOS prioritize routes with the longest prefix length.
3
Next-Hop Extraction
Next-hop IPv4 address 10.0.0.210.0.0.2 is retrieved from the static route entry.
The router identifies that the traffic must be sent to 10.0.0.210.0.0.2 before reaching the final destination.
4
Recursive Route Resolution
Next-hop 10.0.0.210.0.0.2 is resolved to a directly connected exit interface.
Static routes configured solely with next-hop IP addresses require a second routing lookup to identify the physical outbound interface.
5
Layer 2 Resolution & Encapsulation
ARP table maps 10.0.0.210.0.0.2 to its destination MAC address, the packet is encapsulated into a Layer 2 frame, and forwarded.
The router must encapsulate the IP packet into a valid Ethernet frame using the exit interface and next-hop MAC address.

Anahtar Kavram

Recursive Static Route Lookup and Packet Forwarding Sequence
Soru 136Soru →

A network administrator needs to configure reliable static default routing on a Cisco IOS router by tying a primary static route to an IP SLA probes object, ensuring that the route is automatically withdrawn if the target becomes unreachable. Arrange the operational and CLI configuration steps in the correct chronological order from establishing the probe metric to static route activation.

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The correct chronological sequence is: (1) Define and schedule the IP SLA probe instance, (2) Create the object tracking process monitoring IP SLA reachability, (3) Configure the static route bound to the track object ID, and (4) Verify probe success leading to tracking state UP and RIB installation.
The correct sequence follows the mandatory dependency hierarchy in Cisco IOS: first, the IP SLA engine must be defined and scheduled to generate active probes; second, a tracking object must be constructed to translate probe results into a boolean UP/DOWN status; third, the IPv4 static route must be configured with the `track` keyword; and finally, once the tracking object confirms reachability (UP state), the router installs the static route into the routing table (RIB).

Adım Adım Çözüm

1
Configure and schedule the IP SLA ICMP Echo probe operation.
The router begins sending ICMP echo packets to target IP 203.0.113.1203.0.113.1.
Tracking objects require an active underlying probe instance to supply reachability status.
2
Bind the IP SLA operation to a tracking object ID using `track <id> ip sla <ops-number> reachability`.
Tracking object status changes to UP when SLA probe responses are received successfully.
Static routes cannot monitor IP SLA probes directly; they must reference a tracking object.
3
Apply the `ip route` global configuration command specifying the next-hop IP and the `track <id>` parameter.
The static route is created in conditional status linked to tracking object state.
Adding the `track` keyword instructs Cisco IOS to conditionally evaluate RIB placement.
4
Cisco IOS processes the UP status of the tracking object and writes the route to the routing table.
The default static route becomes active in the RIB with Administrative Distance 11.
RIB installation occurs only when the tracked object returns a valid UP reachability state.

Anahtar Kavram

IPv4 Static Route Object Tracking with IP SLA
Soru 137Soru →

A network administrator needs to create a new enterprise wireless network on a Cisco Wireless LAN Controller (WLC) using the GUI. The network must use WPA2-Enterprise with 802.1X authentication via an external RADIUS server and be mapped to an existing dynamic interface. Place the configuration steps in the correct sequential order from first to last.

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The correct sequence to configure the enterprise WLAN via the Cisco WLC GUI is: 1) Create the new WLAN profile and SSID, 2) Map the WLAN to the dynamic interface on the General tab, 3) Select WPA2 and 802.1X key management on the Security > Layer 2 tab, 4) Choose the RADIUS server under the Security > AAA Servers tab, and 5) Select the Status checkbox on the General tab and click Apply.
The proper administrative workflow in the Cisco WLC GUI requires creating the WLAN profile first, mapping the Layer 2/3 dynamic interface on the General tab, configuring Layer 2 security for WPA2 802.1X authentication, defining the RADIUS authentication server under Security > AAA Servers, and finally checking the Status checkbox on the General tab and applying the settings.

Adım Adım Çözüm

1
Initiate new WLAN creation.
Access the WLAN creation screen to assign the Profile Name and SSID.
Creating the basic WLAN profile creates the configuration object in the controller database.
2
Assign the dynamic interface on the General tab.
Associates wireless client connections with the specified IP subnet and VLAN.
Interface binding ensures wireless clients receive network connectivity on the appropriate subnet upon association.
3
Configure Layer 2 security policies under Security > Layer 2.
Enables WPA2-Enterprise with 802.1X Key Management.
Selecting 802.1X key management defines that client authentication relies on EAP and external AAA infrastructure.
4
Assign RADIUS server settings under Security > AAA Servers.
Links the WLAN to the active RADIUS server for identity verification.
Selecting the active RADIUS authentication server directs 802.1X authentication requests to the network access server.
5
Enable the WLAN status on the General tab and apply changes.
Activates the WLAN across connected Access Points.
Cisco WLCs leave newly created WLANs disabled by default to prevent broadcast before security and routing configurations are complete.

Anahtar Kavram

WLC GUI WLAN Configuration Sequence
Tahmini Süre:1m 30s
Soru 138Soru →

A Cisco router receives an IPv4 packet on an ingress interface. Place the sequential steps of the router's forwarding decision and packet processing logic in the correct order from initial receipt to egress transmission.

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The correct sequence for router forwarding decision logic is: 1) Inspect the destination IPv4 address and search the routing table for matching prefixes, 2) Select the route with the longest prefix match, 3) Extract the next-hop IPv4 address and exit interface, 4) Query the ARP cache for the next-hop Layer 2 MAC address, and 5) Decrement packet TTL, encapsulate into a new Layer 2 frame, and transmit out the exit interface.
When a router receives an IPv4 packet, the forwarding process follows a strict sequence: First, the destination IPv4 address is compared against candidate routes in the routing table. Next, the router selects the route entry with the longest prefix match (most specific subnet mask). Once the best route is selected, the router identifies the next-hop IPv4 address and exit interface. It then queries the local ARP cache to find the corresponding destination MAC address for the next hop. Finally, it modifies the packet by decrementing the Time to Live (TTL) by 1, recalculating the IPv4 checksum, encapsulating the packet into a new Layer 2 frame with updated source/destination MAC addresses, and forwarding it out the exit interface.

Adım Adım Çözüm

1
Receive packet and parse IPv4 header.
Destination IPv4 address extracted for routing table comparison.
The router must compare the destination address against candidate prefix entries in the routing table.
2
Apply Longest Prefix Match (LPM) evaluation.
The route entry with the highest mask length (e.g., /28 over /24) is selected.
LPM is the primary rule for forwarding lookup in Cisco routers.
3
Identify forwarding path details.
Next-hop IPv4 address and egress interface determined.
The matching route entry specifies the destination gateway and physical/logical outbound interface.
4
Perform Layer 2 resolution.
Target MAC address obtained from the ARP table.
Layer 2 framing requires the destination MAC address of the next-hop router or end-host.
5
Process packet header modifications and frame encapsulation.
Frame transmitted out the egress interface.
The router updates TTL/checksum fields and constructs new source/destination MAC addresses for outbound transmission.

Anahtar Kavram

Router Forwarding Decision Logic and Layer 2 Frame Rewrite
Tahmini Süre:1m 30s
Soru 139Soru →

Arrange the evaluation steps in the correct order of precedence used by OSPFv2 routers to determine Designated Router (DR) selection on a multiaccess network segment, from the initial eligibility filter to the final tie-breaker.

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The correct order of precedence for OSPFv2 DR selection is: 1) Disqualify priority 0 interfaces, 2) Select the candidate with the highest OSPF interface priority, 3) Break priority ties using the highest explicit Router ID or loopback IPv4 address, and 4) Break remaining ties using the highest active physical interface IPv4 address.
During an OSPFv2 DR election on a multiaccess network segment, candidate routers first exclude any interfaces configured with an OSPF priority of 0. Next, routers compare interface priorities to select the highest value. If interface priorities tie, OSPF compares Router IDs by selecting the candidate with the highest explicitly configured Router ID or highest loopback IPv4 address. Finally, if no loopback interface is present, the highest active physical interface IPv4 address is used as the tie-breaker.

Adım Adım Çözüm

1
Filter out non-eligible candidate interfaces.
Interfaces configured with `ip ospf priority 0` are excluded from DR/BDR candidacy.
A priority of 0 explicitly revokes a router's ability to serve as DR or BDR.
2
Compare candidate interface priority values.
The router with the highest numeric priority value (1 to 255) is preferred.
Interface priority is the primary metric for OSPF DR election.
3
Evaluate Router ID using explicit setting or loopback addresses.
If interface priorities tie, the router with the highest explicit Router ID or highest active loopback IP address is selected.
Router ID serves as the secondary selection criteria when priorities are tied.
4
Evaluate physical interface IP addresses.
If no explicit Router ID or loopback interfaces exist, the highest active physical interface IPv4 address breaks the tie.
Physical interface IPv4 addresses are the final tie-breaker for Router ID assignment and election decisions.

Anahtar Kavram

OSPFv2 DR/BDR Election Precedence
Soru 140Soru →

A Cisco IOS router receives an IPv4 packet destined for host 192.168.2.45192.168.2.45. The router's routing table contains a static route configured as `ip route 192.168.2.0 255.255.255.0 10.1.1.2`. Place the processing steps the router executes to resolve the exit interface and encapsulate the packet in the correct sequential order from first to last.

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Cevap

The correct sequential order for recursive static route lookup and forwarding is: 1) Match destination IP against the routing table to select the static route; 2) Identify next-hop IP address 10.1.1.2; 3) Perform a recursive lookup in the routing table for 10.1.1.2; 4) Match the connected route 10.1.1.0/24 to determine exit interface GigabitEthernet0/1; 5) Retrieve the ARP table entry for 10.1.1.2 to encapsulate and transmit the frame.
When a static route is configured using only a next-hop IP address (e.g., `ip route 192.168.2.0 255.255.255.0 10.1.1.2`), Cisco IOS must execute a recursive lookup process. The router first matches the packet destination IP (192.168.2.45192.168.2.45) against the static route in the routing table. Second, it identifies the configured next-hop IP (10.1.1.210.1.1.2). Third, it performs a secondary (recursive) lookup for 10.1.1.210.1.1.2 in the routing table. Fourth, it finds the directly connected route (10.1.1.0/2410.1.1.0/24), revealing the physical egress interface (GigabitEthernet0/1). Fifth, it queries the ARP table for the MAC address belonging to 10.1.1.210.1.1.2 to build the Ethernet frame and transmit it out GigabitEthernet0/1.

Adım Adım Çözüm

1
Evaluate the incoming packet's destination IPv4 address.
The router matches host destination 192.168.2.45192.168.2.45 to static prefix 192.168.2.0/24192.168.2.0/24.
Routing decisions start by determining the longest matching prefix for the destination IP address.
2
Inspect forwarding parameters specified in the matched static route entry.
The router determines that the route specifies next-hop IP address 10.1.1.210.1.1.2.
Static routes configured strictly with a next-hop IP address do not directly name an exit interface.
3
Execute a recursive lookup for IP address 10.1.1.210.1.1.2.
The router searches the RIB for a route covering 10.1.1.210.1.1.2.
Recursive resolution is mandatory when a next-hop IP is used without an explicit exit interface specification.
4
Resolve the next-hop IP to a connected network route.
The router matches 10.1.1.210.1.1.2 to connected network 10.1.1.0/2410.1.1.0/24 on interface GigabitEthernet0/1.
The connected route provides the physical exit interface necessary to transmit the traffic.
5
Query the ARP table and perform Layer 2 frame encapsulation.
The destination MAC address associated with 10.1.1.210.1.1.2 is acquired and the frame is transmitted via GigabitEthernet0/1.
Multi-access Ethernet media require resolving the next-hop IPv4 address to its target MAC address before physical transmission.

Anahtar Kavram

Recursive Routing Lookup for IPv4 Static Routes
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