Pass the CompTIA CompTIA Network+ N10-009 Questions and answers with CertsForce

•Since this issue occurred after a configuration change on a Layer 3 switch, the most likely cause is misconfigured ACLs (Access Control Lists).

•ACLs control which traffic is allowed or denied, so an incorrect ACL may be blocking access to the file server.

•Why not the other options?

•Switching loop (B): A switching loop occurs at Layer 2 (not Layer 3) and causes network-wide broadcast storms, not just loss of access to a file server.

•Duplicate IP addresses (C): This would cause connectivity issues for the devices with the conflict, but not necessarily prevent all users from accessing the file server.

•Wrong default route (D): The default route is used for traffic leaving the local network. If users are unable to access an internal file server, this is unlikely to be the issue.

Multimode fiber optic cables involve the transmission of light signals that bounce off the core ' s cladding as they travel down the fiber. This characteristic differentiates it from single-mode fiber, where the light travels directly down the fiber without reflecting off the cladding.

Here are some detailed points about multimode fiber cables:

Construction: Multimode fibers have a larger core diameter, typically 50 or 62.5 microns, compared to single-mode fibers, which have a core diameter of about 9 microns.

Light Propagation: The larger core of multimode fiber allows multiple light modes to propagate. These modes travel at different angles, leading to reflections off the core-cladding boundary.

Distance and Bandwidth: Due to modal dispersion, where different light modes arrive at the receiver at different times, multimode fibers are suited for shorter distance applications compared to single-mode fibers. Typical distances are up to 550 meters for 10 Gbps Ethernet using OM4 multimode fiber.

Applications: Multimode fibers are commonly used in LANs (Local Area Networks), data centers, and for shorter distance data transmission due to their cost-effectiveness and ease of installation.

Network References:

CompTIA Network+ N10-007 Official Certification Guide, which covers fiber optic technologies, including the differences between multimode and single-mode fibers.

Cisco Networking Academy: Provides training materials and reference guides on the properties of different fiber optic cables.

Fiber Optic Association (FOA): A professional society dedicated to fiber optics, offering extensive information and certification on fiber optic technologies.

Multimode fibers are specifically designed for short-range communication with higher data rates and are typically used in environments like data centers, where high bandwidth over shorter distances is crucial. The reflections off the cladding, inherent to multimode fiber, facilitate this high-capacity communication.

The correct answer is SLA (Service Level Agreement) because it is a formal, documented contract between a service provider and a customer that defines expected service standards. According to CompTIA Network+ (N10-009) objectives under network operations and service management concepts, an SLA outlines measurable performance metrics such as uptime percentage, response time, throughput, support availability, escalation procedures, and responsibilities of both parties.

An SLA ensures accountability and establishes clear expectations for service delivery. For example, a vendor may guarantee 99.99% uptime, define maximum resolution times for incidents, and specify penalties or credits if performance targets are not met. SLAs are critical in cloud services, ISP agreements, managed services, and enterprise vendor contracts.

An MOU (Memorandum of Understanding) is a non-binding agreement outlining general terms between parties but does not define enforceable service metrics. EOL (End of Life) refers to when a product is no longer sold or supported. EOS (End of Support) indicates when a vendor stops providing updates or assistance for a product.

Therefore, an SLA is the correct document that defines vendor-delivered service requirements.

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Dynamic routing is most beneficial in a growing/changing network because it can automatically learn, adapt, and update routes as the topology changes. In Network+ (N10-009) routing objectives, dynamic routing protocols exchange routing information between routers and recalculate paths when links go down, new networks are added, or metrics change. This reduces the operational burden and the risk of human error that increases as the environment scales. With dynamic routing, adding a new subnet or branch often requires far fewer manual updates because routers propagate new route information automatically, and convergence mechanisms help restore connectivity after failures.

Option A can be partly true in large environments, but the core “best reason” emphasized for dynamic routing is the automatic adaptation to topology changes. Option B is incorrect—dynamic routing may introduce additional security considerations (route filtering, authentication, neighbor control). Option C is not a defining advantage; monitoring visibility depends on tools/telemetry rather than routing type. Therefore, the strongest and most correct reason is automatic changes and updates in network topology.

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To enable communication between VLANs, the technician must configure inter-VLAN routing. On a Layer 3 switch, this is commonly done by creating an SVI (Switched Virtual Interface) for each VLAN. An SVI provides a virtual Layer 3 interface with an IP address that acts as the default gateway for hosts in that VLAN. Once SVIs exist and routing is enabled, the switch can route traffic between VLAN subnets internally, allowing clients in different VLANs to communicate (subject to any security controls). This aligns with Network+ (N10-009) infrastructure objectives covering VLANs, Layer 2/Layer 3 switching, and the requirement for routing to cross broadcast domains.

ACLs can permit or deny inter-VLAN traffic, but they do not create the routing function by themselves. VXLAN is an overlay tunneling technology used mainly in data centers to extend Layer 2 networks over Layer 3 fabrics, not the standard solution for basic VLAN-to-VLAN connectivity on a switch. VPC is not the required configuration element for inter-VLAN routing in this context. Therefore, configuring SVIs is the correct and most direct answer.

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Understanding MTBF:

Mean Time Between Failures (MTBF): A reliability metric that estimates the average time between successive failures of a device or system.

Calculation and Importance:

Calculation: MTBF is calculated as the total operational time divided by the number of failures during that period.

Usage: Used by manufacturers and engineers to predict the lifespan and reliability of a device, helping in maintenance planning and lifecycle management.

Comparison with Other Metrics:

RTO (Recovery Time Objective): The maximum acceptable time to restore a system after a failure.

RPO (Recovery Point Objective): The maximum acceptable amount of data loss measured in time.

MTTR (Mean Time to Repair): The average time required to repair a device or system and return it to operational status.

Application:

MTBF is crucial for planning maintenance schedules, spare parts inventory, and improving the overall reliability of systems.

Quality of Service (QoS) prioritizes delay-sensitive traffic such as VoIP by assigning higher priority in queues, reducing jitter, latency, and packet loss. Implementing QoS policies ensures stable and clear voice communication.

B. STP (Spanning Tree Protocol) prevents switching loops, but it does not address jitter or real-time traffic performance.

References (CompTIA Network+ N10-009):

Domain: Network Infrastructure — QoS, traffic shaping, prioritization of voice/video.

Understanding Subnetting:

The subnet mask 255.255.255.240 (or /28) indicates that each subnet has 16 IP addresses (14 usable addresses, 1 network address, and 1 broadcast address).

Calculating the Subnet Range:

Subnet Calculation: For the IP address 10.0.0.95 with a /28 subnet mask:

Network address: 10.0.0.80

Usable IP range: 10.0.0.81 to 10.0.0.94

Broadcast address: 10.0.0.95

Router Interface Configuration:

Broadcast Address Issue: The IP address 10.0.0.95 is the broadcast address for the subnet 10.0.0.80/28. Configuring a router interface with the broadcast address will cause routing issues as it is not a valid host address.

Comparison with Other Options:

The web server is in a different subnet: The web server (10.0.0.81) is within the same subnet range (10.0.0.80/28).

The IP address space is a class A network: While 10.0.0.0 is a Class A network, this does not explain the routing issue caused by the broadcast address.

The subnet is in a private address space: The private address space designation (RFC 1918) does not impact the routing issue related to the broadcast address configuration.

Resolution:

Reconfigure the router interface with a valid host IP address within the usable range, such as 10.0.0.94.

URL filtering can block access to websites based on their domain or country code TLDs (e.g., .cn, .ru). This is the correct method to block by location identifiers in URLs.

B. Content filtering blocks based on keywords or categories within websites, not country code.

C. DNS poisoning is an attack, not a control mechanism.

D. MAC filtering restricts devices, not websites.

References (CompTIA Network+ N10-009):

Domain: Network Security — Filtering technologies, URL vs content filtering.

If APs are changing channels frequently, it indicates automatic channel selection due to interference. This can cause temporary disconnections as the APs switch frequencies.

Breakdown of Options:

A. Channel interference – ✅ Correct answer. APs change channels automatically to avoid interference, causing disconnections.

B. Roaming misconfiguration – Roaming only affects moving users, but users report issues while stationary.

C. Network congestion – Causes slow speeds, not frequent disconnects.

D. Insufficient wireless coverage – Would cause weak signals, but not channel switching issues.

The correct answer is /25, which is the appropriate subnet mask for dividing an existing Class C network into two equal subnets. According to the CompTIA Network+ N10-009 objectives, subnetting is a core networking concept used to improve network segmentation, performance, and security.

A Class C network uses a default subnet mask of /24 (255.255.255.0), which provides 256 total addresses (254 usable). To split this network into two sections, the administrator must borrow one host bit from the last octet. Borrowing one bit results in a /25 subnet mask (255.255.255.128). This creates two subnets, each with 128 total addresses (126 usable)—an ideal solution for separating two departments such as finance and marketing.

A /24 would not create any segmentation, as it represents the original single network. A /26 would create four subnets, and a /27 would create eight subnets, both of which exceed the requirement of only two sections and unnecessarily reduce the number of available host addresses per subnet.

The Network+ objectives emphasize selecting subnet masks based on organizational requirements, balancing the number of subnets with sufficient host capacity. In this scenario, /25 is the most efficient and correct choice.

VLAN hopping is an attack where an attacker crafts packets with multiple VLAN tags, allowing them to traverse VLAN boundaries improperly. This can result in gaining unauthorized access to network segments that are supposed to be isolated. The other options do not involve the use of multiple network tags. MAC flooding aims to overwhelm a switch’s MAC address table, DNS spoofing involves forging DNS responses, and ARP poisoning involves sending fake ARP messages.

A = 192.168.10.0/26

B = 192.168.1.0/23

C = 10.0.0.1/18

Using the choices shown in the screenshot, the best-fit subnet selections are based on host growth requirements first, then segmentation .

For Company A , the current device count is 32 . With 20% growth , that becomes about 39 devices . A /27 only supports 30 usable hosts , so it is too small. A /26 supports 62 usable hosts , so 192.168.10.0/26 is the correct choice.

For Company B , the current device count is 100 . With 20% growth , that becomes 120 devices . The smallest correct subnet would normally be a /25 with 126 usable hosts , but that option is not shown. From the available choices, 192.168.1.0/23 is the smallest subnet that still supports more than 120 hosts, so that is the best answer.

For Company C , the current device count is 10,000 . With 20% growth , it needs space for 12,000 hosts . A /18 provides 16,382 usable hosts , while a /19 is not available and a /21 or /22 would be far too small. Therefore, 10.0.0.1/18 is the correct selection.

One important note: the dropdown choices shown do not actually let all three companies be placed into a single true Class B network block. So these answers are the best valid selections from the provided options .

On the first exhibit, the layout should be as follows

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Exhibit 2 as follows

Access Point Name AP2

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Exhibit 3 as follows

Access Point Name AP3

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A screenshot of a computer AI-generated content may be incorrect.

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