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Question 541Question →

Which of the following are key operational characteristics of link-state dynamic routing protocols, such as OSPF? (Select TWO)

Select all that apply

Show answer & explanation

Answer: Routers construct a full topology map of the network area to calculate optimal paths.; Updates are sent as triggered link-state updates when topology changes occur rather than on strict full-table timers.

Answer

The correct characteristics are that routers construct a full topology map of the network area to calculate optimal paths, and that updates are sent as triggered link-state updates when topology changes occur.
Link-state dynamic routing protocols maintain full network visibility by constructing a topology database of the area. Additionally, they conserve bandwidth and achieve faster convergence by dispatching triggered LSA updates when link states change instead of constantly broadcasting full routing tables.

Step-by-Step Solution

1
Identify the core mechanics of link-state routing protocols (e.g., OSPF).
Link-state protocols rely on all routers sharing link status information to maintain a synchronized map of the network topology and compute shortest path trees.
Understanding the fundamental differences between link-state and distance-vector protocol updates is critical for evaluating routing protocol behavior.
2
Evaluate update mechanisms for link-state protocols.
Link-state updates are event-driven and triggered upon network changes rather than sending periodic full-table dumps.
Triggered incremental updates reduce bandwidth consumption and improve network convergence speed.
3
Differentiate Layer 3 dynamic routing from Layer 2 switching and NAT services.
Dynamic routing protocols function at Layer 3 to determine paths between networks, distinct from Layer 2 switching or NAT/PAT translation services.
Distinguishing protocol layers and operational scopes prevents confusing routing mechanisms with address translation or switching mechanisms.

Key Concept

Link-State Dynamic Routing Protocol Behavior
Question 542Question →

A network administrator is configuring an IEEE 802.1Q trunk link between two managed switches to carry traffic for multiple VLANs over a single physical cable. Which of the following statements correctly describe the default operation and frame structure of IEEE 802.1Q trunking? (Select TWO.)

Select all that apply

Show answer & explanation

Answer: Frames associated with standard tagged VLANs have a 4-byte header containing the VLAN ID inserted into the Ethernet frame.; Frames belonging to the native VLAN are transmitted across the trunk link without an 802.1Q header tag.

Answer

IEEE 802.1Q trunking inserts a 4-byte tag into frames for tagged VLANs and transmits native VLAN frames without an added VLAN header tag.
IEEE 802.1Q trunking operates by inserting a 4-byte header tag into standard Ethernet frames to identify VLAN membership across switches. Traffic belonging to the native VLAN is transmitted untagged by default.

Step-by-Step Solution

1
Identify how IEEE 802.1Q maintains VLAN separation across a trunk link.
A 4-byte VLAN header tag is inserted into Ethernet frames belonging to tagged VLANs.
The receiving switch reads this tag to determine which VLAN broadcast domain the frame belongs to.
2
Identify how IEEE 802.1Q handles native VLAN traffic.
Frames on the native VLAN are sent across the trunk link without a tag.
Native VLAN support allows untagged legacy traffic or control frames to pass across trunk interfaces.

Key Concept

802.1Q Frame Tagging and Native VLAN Operation
Question 543Question →

A network administrator is establishing stateful firewall rules to allow remote administrative workstations to securely manage internal Linux servers via encrypted command-line sessions and authenticate against a directory server using SSL/TLS encryption. Unencrypted management traffic must remain strictly blocked. Which TWO port and transport protocol combinations must be explicitly permitted to support these administrative requirements? (Select TWO.)

Select all that apply

Show answer & explanation

Answer: TCP port 22; TCP port 636

Answer

TCP port 22 (for SSH) and TCP port 636 (for LDAPS) must be explicitly permitted.
Encrypted remote terminal access is provided by SSH over TCP port 22. Encrypted directory services authentication is provided by LDAPS over TCP port 636. Both protocols require connection-oriented TCP transport to establish stateful, reliable cryptographic sessions.

Step-by-Step Solution

1
Identify the protocol required for secure remote command-line administration.
Secure Shell (SSH) is required, which operates on standard TCP port 22.
SSH replaces unencrypted Telnet (TCP 23) to satisfy secure remote administration policies.
2
Identify the protocol required for encrypted directory service queries.
Lightweight Directory Access Protocol over SSL/TLS (LDAPS) is required, which operates on standard TCP port 636.
LDAPS encrypts directory authentication traffic, whereas unencrypted LDAP uses TCP port 389.
3
Verify the correct Transport Layer protocol for both services.
Both SSH and LDAPS rely on TCP for connection reliability and TLS/session handling.
UDP is connectionless and cannot support the reliable handshakes required by SSH and TLS encryption streams.

Key Concept

Standard service port numbers and transport protocol selection for secure remote access and directory services
Question 544Question →

A network administrator is designing a dedicated, fault-tolerant interconnect architecture for 55 mission-critical database nodes within a single data center rack. To ensure continuous operation without a central point of failure, every node must have a direct point-to-point physical cable connection to every other node in the cluster. Which network topology is being implemented, and what is the total number of physical cabling links required for this configuration?

Show answer & explanation

Answer: Full mesh topology requiring 10 physical links

Answer

Full mesh topology requiring 10 physical links
The design specifies a fully redundant layout where every node has a direct, dedicated physical connection to every other node, which defines a full mesh topology. The total number of required links for n=5n = 5 nodes is calculated using the formula n(n−1)2\frac{n(n-1)}{2}, resulting in 5×(5−1)2=10\frac{5 \times (5-1)}{2} = 10 physical links.

Step-by-Step Solution

1
Identify the topology based on structural requirements
Full mesh topology
Connecting every node directly to every other node without an intermediary device defines a physical full mesh topology.
2
Calculate required physical links using the mesh formula
10 physical links
The formula for calculating un-directed connections in a full mesh network with nn nodes is L=n(n−1)2L = \frac{n(n-1)}{2}. Substituting n=5n = 5 yields 5×42=10\frac{5 \times 4}{2} = 10.

Key Concept

Full Mesh Topology and Link Calculation
Estimated Time:1m 30s
Question 545Question →

In an enterprise network running Per-VLAN Spanning Tree Plus (PVST+), two switches (Switch A and Switch B) are interconnected. Switch A has a base MAC address of 00:11:22:33:44:55 and is configured with an STP base priority of 28672 for VLAN 50. Switch B has a base MAC address of 00:11:22:33:44:AA and currently operates with the default STP base priority of 32768 for VLAN 50. A network administrator wants Switch B to become the Root Bridge for VLAN 50. Which priority value must be configured on Switch B for VLAN 50 to guarantee it becomes the Root Bridge?

Show answer & explanation

Answer: 24576

Answer

Setting the base priority of Switch B to 24576 ensures it achieves a lower Bridge ID than Switch A and becomes the Root Bridge for VLAN 50.
In Spanning Tree Protocol, the switch with the lowest Bridge ID (BID) is elected as the Root Bridge. BID consists of Bridge Priority + System ID Extension (VLAN ID) + Base MAC Address. Configured in steps of 4096, setting Switch B's priority to 24576 results in a total priority of 24626, lower than Switch A's total priority of 28722, securing the Root Bridge election for Switch B.

Step-by-Step Solution

1
Calculate Switch A's total Bridge ID priority for VLAN 50
28672 (base priority) + 50 (System ID Extension for VLAN 50) = 28722
PVST+ combines the 4-bit priority field with the 12-bit VLAN ID extension to form the total priority portion of the Bridge ID.
2
Evaluate the outcome if Switch B matches Switch A's base priority of 28672
Total priority tie (28722 vs 28722). Switch A wins based on lower MAC address (00:11:22:33:44:55 < 00:11:22:33:44:AA).
When total priorities are equal, Spanning Tree Protocol uses the switch base MAC address as the ultimate tiebreaker, where lower numerical value wins.
3
Determine the required priority increment to guarantee Switch B wins
Select the next lower valid STP priority increment of 4096 below 28672, which is 24576.
Bridge priorities must be configured in multiples of 4096. A base priority of 24576 gives Switch B a total priority of 24626, which is lower than Switch A's 28722.

Key Concept

STP Root Bridge Selection and Priority Tie-Breaking Logic
Estimated Time:2m 0s
Question 546Question →

When a router receives route advertisements from different sources for the exact same destination network, it evaluates their trustworthiness using Administrative Distance (AD). How should the following route sources be ordered from the lowest administrative distance (most trustworthy) to the highest administrative distance (least trustworthy)?

Drag items to arrange them in the correct order

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Answer

The correct sequence from lowest to highest Administrative Distance is: Directly connected interface (AD = 00), Static route (AD = 11), OSPF dynamic route (AD = 110110), and RIP dynamic route (AD = 120120).
Administrative Distance (AD) is a feature used by routers to select the best path when there are two or more different routes to the same destination from different routing protocols. The default AD values in increasing order are: Directly connected interfaces (00), Static routes (11), OSPF (110110), and RIP (120120).

Step-by-Step Solution

1
Identify the Administrative Distance (AD) value for each route source
Directly connected interface = 00, Static route = 11, OSPF = 110110, RIP = 120120.
Administrative distance measures route reliability on a scale from 00 to 255255, where lower values are preferred.
2
Arrange the sources in ascending numeric order of their AD values
00 (Directly connected) < 11 (Static) < 110110 (OSPF) < 120120 (RIP).
Lower AD values indicate higher trust and are selected first by the router.

Key Concept

Administrative Distance Hierarchy
Question 547Question →

A network security team is replacing insecure legacy protocols across core infrastructure routers. The new baseline policy requires allowing only encrypted protocols for remote command-line administration and web-based graphical configuration. Which TWO of the following transport protocols and default port numbers must be permitted through the administrative management access control list (ACL) to meet these requirements?

Select all that apply

Show answer & explanation

Answer: SSH operating over TCP port 22; HTTPS operating over TCP port 443

Answer

SSH operating over TCP port 22 and HTTPS operating over TCP port 443 are the correct secure choices.
SSH on TCP port 22 provides secure, encrypted shell access for command-line management, while HTTPS on TCP port 443 provides encrypted web management using TLS. Together, these two fulfill the requirement for secure remote administration across CLI and GUI channels.

Step-by-Step Solution

1
Identify the remote management functional requirements.
Requirements specify encrypted command-line administration and secure web-based GUI configuration.
Cleartext protocols must be filtered out in favor of secure cryptographically backed alternatives.
2
Match secure command-line administration to its protocol and port.
SSH utilizes TCP port 22 to encrypt remote shell sessions.
Telnet on TCP port 23 is unencrypted and unacceptable.
3
Match secure web configuration to its protocol and port.
HTTPS utilizes TCP port 443 to encrypt HTTP traffic using TLS.
HTTP on TCP port 80 lacks payload encryption.

Key Concept

Secure remote management protocol and port pairing
Estimated Time:1m 15s
Question 548Question →

A network engineer is configuring switch interface `GigabitEthernet1/0/12` on `SW-DIST-05` to connect a multi-SSID wireless access point. Management traffic from the access point must travel untagged on VLAN 15, while client traffic is tagged on VLAN 45 (Corporate) and VLAN 85 (Guest).

Initially, the interface was configured as follows:
text switchport mode trunk switchport trunk native vlan 15 switchport trunk allowed vlan 15,45,85
During a maintenance window, a junior technician updates the interface configuration by executing:
text switchport trunk allowed vlan 45,85
Which of the following describes the immediate operational outcome of this configuration change?

Show answer & explanation

Answer: Untagged management traffic on VLAN 15 will be dropped at the switchport because VLAN 15 is missing from the allowed VLAN list.

Answer

Untagged management traffic on VLAN 15 will be dropped at the switchport because VLAN 15 is missing from the allowed VLAN list.
On an 802.1Q trunk, the interface filters both tagged and untagged traffic using the allowed VLAN list. When the native VLAN (VLAN 15) is removed from the allowed VLAN list, untagged management frames arriving from the wireless access point are dropped by the switch interface because VLAN 15 is no longer permitted on the link.

Step-by-Step Solution

1
Analyze the original trunk configuration.
Interface `GigabitEthernet1/0/12` was configured to use VLAN 15 as the native VLAN, allowing untagged frames from the AP to be processed in VLAN 15. The allowed list explicitly permitted VLANs 15, 45, and 85.
By default, an 802.1Q trunk processes untagged ingress frames into the designated native VLAN.
2
Evaluate the impact of the modification command.
The technician ran `switchport trunk allowed vlan 45,85`, overwriting the allowed list and removing VLAN 15.
On Cisco switches, `switchport trunk allowed vlan <list>` replaces the current allowed VLAN set rather than appending to it unless the `add` keyword is used.
3
Determine the forwarding behavior for native VLAN traffic when excluded from the allowed list.
Because VLAN 15 is no longer in the allowed list, any untagged ingress or egress frames associated with native VLAN 15 are pruned/dropped at the trunk port.
An 802.1Q trunk interface only forwards traffic for VLANs present in its active allowed VLAN list, regardless of the native VLAN setting.

Key Concept

802.1Q Trunk Allowed VLAN Pruning and Native VLAN Processing
Question 549Question →

A network technician is deploying multiple wireless access points across an office floor using the 2.4 GHz frequency band in North America. To prevent co-channel interference between adjacent access points, the technician needs to select channels that do not overlap. Which combination of channels should the technician assign to the access points?

Show answer & explanation

Answer: Channels 1, 6, and 11

Answer

Channels 1, 6, and 11 are the three standard non-overlapping channels in the 2.4 GHz wireless spectrum for North America.
In 2.4 GHz wireless deployments in North America, standard Wi-Fi signals occupy 20 MHz of channel bandwidth. Because center frequencies are spaced 5 MHz apart, selecting channels 1, 6, and 11 provides a 25 MHz separation between center frequencies, ensuring complete frequency isolation with zero overlap.

Step-by-Step Solution

1
Analyze the bandwidth and channel spacing in the 2.4 GHz spectrum.
The 2.4 GHz Wi-Fi spectrum uses 20 MHz wide channels spaced 5 MHz apart from center-to-center.
Understanding spacing vs bandwidth is essential to determine frequency overlap.
2
Determine the required separation between non-overlapping channels.
Channels require a spacing of at least 5 channel numbers (25 MHz) between center frequencies to prevent spectral overlap.
A 25 MHz separation ensures that signal sidebands do not interfere with neighbouring transmissions.
3
Identify the standard non-overlapping channel set.
Channels 1, 6, and 11 provide the necessary 25 MHz separation across the 11 available channels in North America.
Using channels 1, 6, and 11 allows multi-AP deployment without co-channel interference.

Key Concept

2.4 GHz Wireless Non-Overlapping Channels
Question 550Question →

Match each network documentation type to its primary operational purpose.

Click a left item, then click its matching right item

Items

Physical Topology Diagram
Network Baseline Documentation
Change Management Log
IDF/MDF Floor Layout Diagram

Matches

Show answer & explanation

Answer

The physical topology diagram matches identifying physical port connections and cable runs; network baseline documentation matches establishing standard operating performance metrics; change management log matches tracking historical network modifications; and the IDF/MDF floor layout diagram matches visualizing physical room locations and rack positioning.
Each item correctly matches its operational documentation purpose: physical topology diagrams detail cabling and interface connections; network baselines document typical performance levels to identify anomalies; change management logs record historic infrastructure modifications; and IDF/MDF layout diagrams visually map telecommunications rooms and rack arrangements.

Step-by-Step Solution

1
Analyze the purpose of a Physical Topology Diagram
Physical topology maps depict actual hardware cables, physical ports, and device interfaces.
This corresponds directly to identifying physical port connections and cable runs.
2
Analyze the purpose of Network Baseline Documentation
Baseline records capture standard network performance metrics during normal operation.
This provides a reference point for comparing future performance anomalies.
3
Analyze the purpose of a Change Management Log
Change logs keep track of who changed what, when, and why across network infrastructure.
This corresponds to tracking historical network modifications and updates.
4
Analyze the purpose of an IDF/MDF Floor Layout Diagram
IDF/MDF layout diagrams depict physical building space, telecommunications closets, and equipment racks.
This corresponds to visualizing room locations and spatial rack placement.

Key Concept

Network Documentation Types and Use Cases
Estimated Time:1m 0s
Question 551Question →

A network technician is documenting a newly commissioned telecommunications room to assist on-site staff with pinouts, cable runs, wall outlet terminations, and patch panel port locations. The documentation must detail exact physical conductor connections and jack numbers without detailing IP addressing schemes or device rack unit placements. Which document type should the technician prepare?

Show answer & explanation

Answer: Wiring schematic

Answer

The correct document to prepare is a wiring schematic, as it specifies low-level physical wiring paths, pinouts, patch panel terminations, and port labeling.
A wiring schematic (or cable run diagram) focuses explicitly on Layer 1 infrastructure details, such as color code standards (T568A/T568B), cable run IDs, wall jack labels, and patch panel port assignments.

Step-by-Step Solution

1
Analyze the requirements stated in the scenario.
Identified the need to document physical cable paths, pinouts, patch panel terminations, and wall jack IDs at Layer 1.
The scenario emphasizes physical cable tracing rather than device placement or logical IP configuration.
2
Evaluate candidate documentation types against Layer 1 physical requirements.
Wiring schematics focus specifically on pinout diagrams, cable run details, and physical port terminations.
Wiring schematics provide granular connection mapping for technicians performing physical installation and cable troubleshooting.
3
Differentiate from alternative diagram types.
Logical diagrams cover IP/VLAN layouts; rack elevations cover physical unit heights; baselines cover performance metrics.
Selecting the incorrect diagram type leads to missing essential pinout and termination details during physical maintenance.

Key Concept

Wiring Schematics and Cable Documentation
Question 552Question →

An enterprise core network routes traffic using several dynamic interior and exterior routing protocols alongside static routing rules. Match each routing protocol or forwarding evaluation rule on the left with its exact operational metric or selection characteristic on the right.

Click a left item, then click its matching right item

Items

Internal BGP (iBGP)
OSPFv2
Internal EIGRP
Longest Prefix Match

Matches

Show answer & explanation

Answer

Internal BGP matches with default AD 200 and AS_PATH preservation; OSPFv2 matches with bandwidth cost metric and AD 110; Internal EIGRP matches with composite bandwidth/delay metric and AD 90; Longest Prefix Match matches with overriding all AD and metric evaluations during lookup.
Each protocol and lookup rule follows strict architectural standards: iBGP operates at AD 200, OSPF calculates cost based on bandwidth with AD 110, EIGRP uses composite metrics with AD 90, and Longest Prefix Match serves as the primary route selection criterion before AD or metrics are evaluated.

Step-by-Step Solution

1
Analyze Longest Prefix Match hierarchy
Identify that prefix mask length (/28 vs /24) takes absolute priority over Administrative Distance and routing metrics during packet forwarding.
Longest Prefix Match is evaluated first before comparing Administrative Distance among competing routes.
2
Evaluate internal BGP Administrative Distance and AS_PATH propagation
Associate iBGP with AD 200 and unchanged AS_PATH propagation.
iBGP routes have an AD of 200 (compared to eBGP's AD of 20) to ensure local IGP routes take precedence unless explicitly configured otherwise.
3
Differentiate IGP metrics and Administrative Distances (OSPF vs EIGRP)
Match OSPF to inverse bandwidth cost formula with AD 110, and EIGRP to composite vector metric (minimum bandwidth + cumulative delay) with AD 90.
OSPF evaluates link costs calculated from bandwidth, whereas EIGRP uses vector composite metrics.

Key Concept

Routing table path selection order, administrative distance hierarchy, and dynamic protocol metric calculation mechanisms.
Question 553Question →

A core router receives an IPv4 packet destined for a remote network host. The router's routing table contains multiple paths learned via different dynamic routing protocols, static routes, and directly connected subnets. Place the decision-making steps in the exact sequential order that the router's control plane uses to evaluate the candidate paths and forward the packet to the next hop.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence for packet forwarding decision logic is: 1) Apply Longest Prefix Match to filter candidates by subnet specificity, 2) Compare Administrative Distance to select the most reliable route source among matching prefix lengths, 3) Compare metric values among routes from the same routing source to identify the lowest-cost path, and 4) Resolve the next-hop Layer 2 destination address for frame encapsulation on the egress interface.
Route lookup logic follows a strict hierarchy. First, Longest Prefix Match (LPM) determines subnet specificity. Second, among candidate routes with equal prefix length, Administrative Distance (AD) selects the most reliable protocol source. Third, for ties within the same protocol source, metric values isolate the optimal cost path. Finally, Layer 2 ARP resolution encapsulates the packet onto the egress link.

Step-by-Step Solution

1
Evaluate subnet mask specificity (Longest Prefix Match)
The router identifies all routes matching the destination IP and isolates those with the longest prefix length (e.g., /28 over /24).
Prefix length takes ultimate precedence in IP route lookup; a more specific route is always chosen over a less specific one.
2
Compare Administrative Distance
If multiple routing sources (e.g., OSPF vs BGP) advertise the exact same prefix length, the router selects the source with the lowest AD.
Administrative Distance ranks the believability of different route sources when prefix lengths match.
3
Evaluate Protocol Metrics
If multiple paths exist from the same routing protocol with equal prefix length and AD, the router selects the path with the lowest metric (or uses ECMP).
Metrics measure path cost within a single routing protocol instance.
4
Perform Data Link Layer Encapsulation
The router looks up the next-hop IP in the ARP table to map the destination MAC address and forwards the frame out the designated physical/logical interface.
Forwarding decision is complete, allowing physical Layer 2 frame transmission.

Key Concept

Route Selection Precedence (Longest Prefix Match -> Administrative Distance -> Metric -> Egress Encapsulation)
Question 554Question →

A network administrator is documenting a public web server's full 128-bit IPv6 address, which is written as 2001:0db8:0000:0042:0000:0000:0000:0001. To ensure consistent configuration across system records, the administrator needs to condense this address using standard zero-compression rules. Which of the following represents the correctly compressed IPv6 address according to RFC 5952 standards?

Show answer & explanation

Answer: 2001:db8:0:42::1

Answer

2001:db8:0:42::1 is the correctly compressed IPv6 address according to RFC 5952 guidelines.
According to RFC 5952 IPv6 representation standards: 1) Leading zeros in any hexadecimal field must be removed (e.g., 0db8 becomes db8, 0042 becomes 42, 0001 becomes 1). 2) The double-colon (::) symbol must be used to compress the longest contiguous sequence of zero fields (positions 5–7). 3) Single zero fields outside the double-colon sequence must be represented as a single '0'. Therefore, 2001:db8:0:42::1 is the only valid, standard-compliant compressed form.

Step-by-Step Solution

1
Remove leading zeros from each 16-bit hexadecimal field.
2001:0db8 becomes 2001:db8, 0000 becomes 0, 0042 becomes 42, and 0001 becomes 1.
RFC 5952 requires leading zeros in any four-digit hexadecimal group to be omitted.
2
Identify all contiguous runs of zero fields and locate the longest sequence.
The address contains two zero sequences: one single zero field at position 3 (0), and a contiguous run of three zero fields at positions 5, 6, and 7 (0000:0000:0000).
The double-colon (::) must be used to replace the longest contiguous run of 16-bit zero fields.
3
Replace the longest run of zero fields with a single double-colon (::) and keep single zero fields as '0'.
The sequence 0000:0000:0000 becomes ::, resulting in 2001:db8:0:42::1.
Using :: more than once creates ambiguity regarding how many zero fields were compressed.

Key Concept

IPv6 Address Compression and Canonical Representation (RFC 5952)
Estimated Time:1m 0s
Question 555Question →

A network engineer is troubleshooting interconnectivity between two switches, Switch-Alpha and Switch-Beta, over a dedicated GigabitEthernet link. The switchport configuration for interface GigabitEthernet1/0/24 on both switches is shown below:

Switch-Alpha:
interface GigabitEthernet1/0/24
switchport mode trunk
switchport trunk native vlan 50
switchport trunk allowed vlan 10,20,50

Switch-Beta:
interface GigabitEthernet1/0/24
switchport mode trunk
switchport trunk native vlan 1
switchport trunk allowed vlan 10,20,50

A host in VLAN 10 on Switch-Alpha sends data to a host in VLAN 10 on Switch-Beta. Simultaneously, an untagged broadcast frame is generated by a device in VLAN 50 on Switch-Alpha and transmitted across the link.

Which statement accurately describes how these frames are handled across the trunk link?

Show answer & explanation

Answer: Tagged frames belonging to VLAN 10 cross the trunk link normally, while untagged frames sent from VLAN 50 on Switch-Alpha are placed into VLAN 1 upon arrival at Switch-Beta.

Answer

Tagged frames belonging to VLAN 10 cross the trunk link normally, while untagged frames sent from VLAN 50 on Switch-Alpha are placed into VLAN 1 upon arrival at Switch-Beta.
Under 802.1Q encapsulation, frames belonging to allowed tagged VLANs (such as VLAN 10) are explicitly tagged and delivered correctly across the trunk. However, frames originating from VLAN 50 on Switch-Alpha are egressed untagged because VLAN 50 is Switch-Alpha's native VLAN. When Switch-Beta receives these untagged frames, it classifies them according to its own native VLAN setting (VLAN 1), leading to native VLAN traffic leakage between VLAN 50 and VLAN 1.

Step-by-Step Solution

1
Analyze the handling of tagged VLAN traffic across the trunk link.
VLAN 10 is configured in the allowed list on both ends of the trunk. Switch-Alpha adds an 802.1Q tag (VLAN ID 10) to the frame. Switch-Beta reads the tag, accepts the frame, and forwards it to VLAN 10.
802.1Q trunks maintain tag headers for non-native allowed VLANs regardless of native VLAN configuration.
2
Analyze the egress behavior for VLAN 50 on Switch-Alpha.
Because VLAN 50 is Switch-Alpha's configured native VLAN on GigabitEthernet1/0/24, frames originating in VLAN 50 are transmitted out the trunk port untagged (without an 802.1Q header).
By default in IEEE 802.1Q specification, traffic matching the local interface's native VLAN is sent unencapsulated.
3
Analyze the ingress behavior for untagged frames arriving at Switch-Beta.
Switch-Beta receives the untagged frame and associates it with its own configured native VLAN, which is VLAN 1.
When a trunk port receives an untagged frame, it automatically assigns that frame to whichever VLAN is defined as native on its local interface.

Key Concept

802.1Q Native VLAN Ingress/Egress Behavior during a Trunk Mismatch
Question 556Question →

Match each Layer 2 switching concept on the left with its corresponding operational description on the right.

Click a left item, then click its matching right item

Items

802.1Q Tagging
Native VLAN
Port Security
PortFast

Matches

Show answer & explanation

Answer

802.1Q Tagging matches inserting a 4-byte VLAN header; Native VLAN matches carrying untagged traffic; Port Security matches MAC address restriction; PortFast matches bypassing STP listening and learning states.
Each concept pairs directly with its functional definition: 802.1Q tagging adds VLAN identification headers over trunks, Native VLAN transports untagged frames, Port Security restricts access by MAC address, and PortFast bypasses intermediate STP convergence states for faster link availability.

Step-by-Step Solution

1
Analyze trunk encapsulation mechanisms.
802.1Q encapsulation modifies standard Ethernet frames by inserting a 4-byte VLAN header containing a 12-bit VLAN ID.
This allows switches to identify traffic belonging to specific VLANs across shared trunk connections.
2
Examine untagged frame handling over trunk lines.
Untagged frames belong to the Native VLAN, which transports them across 802.1Q trunks without adding headers.
Native VLAN configuration allows backward compatibility with legacy non-tagging switch ports and control protocols.
3
Evaluate Layer 2 access control features.
Port Security controls ingress traffic based on configured or dynamically learned MAC addresses.
It prevents unauthorized endpoints from sending traffic by taking restrict, protect, or shutdown actions upon violation.
4
Review Spanning Tree Protocol (STP) convergence optimization.
PortFast enables immediate transition to the forwarding state for edge ports.
Edge connections to end-user workstations do not form switching loops, making listening and learning delays unnecessary.

Key Concept

Switching Concepts and VLAN Operations
Question 557Question →

A network administrator is configuring a small internal network and needs a basic distance-vector dynamic routing protocol that uses hop count as its sole metric for path selection. Which of the following dynamic routing protocols meets this requirement?

Show answer & explanation

Answer: Routing Information Protocol (RIP)

Answer

Routing Information Protocol (RIP) is a distance-vector protocol that measures path cost purely using hop count.
Routing Information Protocol (RIP) is a traditional distance-vector interior gateway protocol that measures distance purely in terms of hop count, where each router along the path counts as one hop.

Step-by-Step Solution

1
Identify the routing protocol category and path selection criteria specified in the scenario.
The requirement calls for a distance-vector protocol using hop count as its metric.
Different dynamic routing protocols use distinct metrics to calculate best paths.
2
Evaluate the metric calculation method of each candidate protocol.
RIP counts the number of routers (hops) to the destination. OSPF uses bandwidth cost, EIGRP uses composite bandwidth/delay, and BGP uses path attributes.
Matching the metric mechanism identifies the correct protocol.

Key Concept

Routing Metrics and Dynamic Routing Protocols
Question 558Question →

A network administrator connects two enterprise switches, Switch-Alpha and Switch-Beta, via an 802.1Q trunk link. Switch-Alpha is configured with a bridge priority of 28672 for VLAN 50, while Switch-Beta retains the default bridge priority of 32768 for VLAN 50. Additionally, the trunk port on Switch-Alpha has a native VLAN of 50, whereas the trunk port on Switch-Beta is configured with a native VLAN of 1. Which TWO of the following statements correctly describe the Layer 2 behavior and spanning tree status of this configuration?

Select all that apply

Show answer & explanation

Answer: Switch-Alpha will be elected as the Spanning Tree Protocol (STP) Root Bridge for VLAN 50 because it possesses a lower numerical bridge priority than Switch-Beta.; A native VLAN mismatch error will occur because the native VLAN configurations on opposing ends of the 802.1Q trunk do not match.

Answer

The correct statements are that Switch-Alpha will be elected as the Spanning Tree Protocol (STP) Root Bridge for VLAN 50 due to its lower bridge priority, and a native VLAN mismatch error will be generated due to inconsistent native VLAN settings across the trunk link.
Switch-Alpha has a lower numerical bridge priority value (28672 vs 32768), which wins the STP root bridge election for VLAN 50. Simultaneously, configuring native VLAN 50 on one end of an 802.1Q trunk and native VLAN 1 on the other creates an operational native VLAN mismatch.

Step-by-Step Solution

1
Evaluate the Spanning Tree Protocol (STP) root bridge election criteria.
STP selects the root bridge based on the lowest Bridge ID (Bridge Priority + MAC address). Switch-Alpha (28672) has a lower priority value than Switch-Beta (32768), making Switch-Alpha the root bridge for VLAN 50.
Lower priority numbers represent higher precedence in STP root bridge selection.
2
Analyze the 802.1Q trunk port configuration parameters on both switches.
Switch-Alpha uses native VLAN 50 while Switch-Beta uses native VLAN 1. This inconsistency generates a native VLAN mismatch diagnostic notification.
IEEE 802.1Q trunks must share identical native VLAN configurations on both connected interfaces to handle untagged traffic correctly.

Key Concept

STP Root Bridge Priority Selection and 802.1Q Native VLAN Trunk Consistency
Estimated Time:2m 0s
Question 559Question →

A network administrator is auditing the core infrastructure configuration for a enterprise environment with centralized network services. Centralized DHCP and DNS servers are deployed on VLAN 10 (10.10.10.0/2410.10.10.0/24), while client endpoints reside on remote VLAN 20 (10.10.20.0/2410.10.20.0/24) and utilize dual-stack IPv4/IPv6 addressing. Which TWO of the following administrative configurations or operational mechanisms are necessary to enable clients on VLAN 20 to automatically obtain valid IPv4 lease configurations and dynamically register their hostnames in name resolution services? (Select TWO.)

Select all that apply

Show answer & explanation

Answer: Configuring an IP helper address (DHCP relay) on the VLAN 20 gateway interface pointing to the unicast IP address of the DHCP server; Enabling Dynamic DNS (DDNS) integration between the DHCP server and the DNS server to update A and AAAA records automatically upon lease issuance

Answer

The required mechanisms are configuring an IP helper address on the remote gateway interface to forward DHCP broadcasts across subnets, and configuring Dynamic DNS (DDNS) integration to update DNS records automatically upon lease issuance.
To allow client endpoints on VLAN 20 to receive dynamic IP address assignments from a DHCP server located on VLAN 10, the Layer 3 interface (gateway) for VLAN 20 must be configured with an IP helper address (DHCP relay agent) to convert local broadcasts into routed unicast traffic. Additionally, to ensure these dynamically addressed hosts can be resolved by name, Dynamic DNS (DDNS) must be enabled so that the DHCP server automatically registers and updates the host's A (IPv4) and AAAA (IPv6) records on the DNS server upon issuing a lease.

Step-by-Step Solution

1
Analyze the Layer 3 boundary requirement for DHCP broadcast traffic.
Identified that clients on VLAN 20 (10.10.20.0/2410.10.20.0/24) send DHCPDISCOVER as Layer 2/3 broadcasts, which routers drop by default. An IP helper address must be configured on the default gateway to relay DHCP traffic across subnets to the server on VLAN 10.
DHCP relay agents convert local broadcast requests into unicast packets routed directly to the DHCP server.
2
Analyze the requirement for dynamic hostname registration.
Identified that Dynamic DNS (DDNS) allows the DHCP server or clients to automatically notify the DNS server to create or update resource records whenever an IP lease is granted.
Without DDNS, client name resolution requires manual DNS administration for dynamic endpoints.
3
Evaluate the incorrect options based on networking protocols and service roles.
PTR records perform reverse lookups (not forward lookups), APIPA indicates DHCP discovery failure and cannot be routed, and Port 23 is Telnet rather than DHCP UDP ports 67/68.
Verifies that distractors contain fundamental protocol or misconfiguration errors.

Key Concept

IP Addressing Services (DHCP Relay and DDNS)
Question 560Question →

A network technician is configuring traffic inspection policy on a next-generation firewall to monitor operations occurring specifically at Layer 4 of the OSI model. Which of the following primary functions takes place at this layer of the OSI model?

Show answer & explanation

Answer: Segmenting data streams from higher layers and providing optional connection-oriented reliability or flow control.

Answer

Segmenting data streams from higher layers and providing optional connection-oriented reliability or flow control.
The correct option highlights the fundamental duties of the Transport Layer (Layer 4). Layer 4 is responsible for breaking upper-layer application data into manageable segments, reassembling them at the destination, and managing mechanisms such as flow control, sequence numbering, and error recovery (via protocols like TCP).

Step-by-Step Solution

1
Identify the requested OSI layer from the question stem.
The target layer specified is Layer 4 (the Transport Layer).
The firewall rule context requires identifying the exact functional boundary of Layer 4.
2
Analyze the functional responsibilities of Layer 4.
Layer 4 handles end-to-end transport functions such as segmentation, flow control, multiplexing via port numbers, and optional connection reliability (e.g., TCP acknowledgments).
This establishes the core operation separating transport functions from lower physical/network routing layers and upper presentation/application layers.
3
Evaluate the option descriptions to select the correct functional matching.
The selection describing segmentation of data streams and flow control correctly matches Layer 4 functions.
All other options describe operations belonging to Layer 6 (Presentation), Layer 3 (Network), and Layer 2 (Data Link).

Key Concept

OSI Layer 4 (Transport Layer) Functions
Estimated Time:1m 0s
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