CompTIA N10-009 - CompTIA Network+ Certification Exam

The correct answer is A. The TX/RX connection is transposed. In fiber optic networking, communication requires proper alignment of the transmit (TX) and receive (RX) strands between devices. If these are reversed (not crossed correctly), the devices cannot properly send and receive signals, resulting in no link light. This is a common issue when working with fiber connections and media converters.

The scenario confirms that cables are tested and functional, and all devices are powered on, which eliminates physical damage or power issues. Fiber cables can still pass basic continuity tests while being incorrectly connected (TX to TX and RX to RX instead of TX to RX), which prevents link establishment.

Option B is incorrect because duplex mismatch (such as half vs. full duplex) typically causes performance issues like collisions and slow throughput, not a complete loss of link light. Option C is ruled out because the cables were tested successfully. Option D refers to errors that occur after a link is established, not a condition preventing link initialization.

According to CompTIA Network+ objectives, proper fiber polarity (TX/RX alignment) is critical for link establishment, making this the most accurate cause.

The most common protocol for secure VPNs is IPsec (Internet Protocol Security). IPsec provides confidentiality, integrity, and authentication for VPN traffic, typically using ESP (Encapsulating Security Payload). It is used in both site-to-site and remote access VPNs.

B. GRE encapsulates traffic but does not provide encryption.

C. BGP is a routing protocol, not a VPN technology.

D. SSH can be used for secure tunneling but is not the standard for VPN deployment.

IPsec is the industry standard because it operates at Layer 3, securing IP traffic regardless of the application, making it highly versatile.

References (CompTIA Network+ N10-009):

Domain: Network Security — VPN protocols, IPsec, ESP.

If the three new employees can communicate with each other’s devices, that strongly suggests their local Layer 2/Layer 3 connectivity is working (same VLAN/subnet, switching is fine, and they have IP addressing that allows local communication). The fact that they cannot access company resources (often on other subnets, servers, or the internet via internal routing) points to a problem with how these new endpoints are being addressed or routed beyond their local segment.

The most likely shared root cause affecting only “new employees” is DHCP scope/pool configuration. If the DHCP pool is exhausted, mis-scoped, or handing out incorrect options (such as an incorrect default gateway, wrong subnet mask, or an address range tied to an isolated VLAN), users could still talk locally but fail to reach resources outside their subnet. Modifying the DHCP server pool (expanding the scope, correcting the scope network, or ensuring the correct options are assigned) would resolve this with minimal changes.

A gateway routing table issue would typically affect many users, not just three new ones. DNS misconfiguration on the router would more commonly cause name-resolution problems, not block all resource access (and wouldn’t be isolated to only new employees). A workstation firewall would not usually prevent access to “company resources” in a way that consistently affects three new devices while still allowing peer connectivity.

Site-to-Site VPN: A site-to-site VPN is used to securely connect two networks, such as a company ' s headquarters and a branch location, over the internet. This type of VPN creates a secure tunnel for data transmission, ensuring confidentiality and integrity.

Split-tunnel VPN (A): Allows some traffic to bypass the VPN tunnel, which may not secure all communications.

Clientless VPN (B): Used for individual users to access the network without VPN client software.

Full-tunnel VPN (C): Typically used for individual user traffic rather than connecting two networks.

The right answer is A. Trap. In SNMP, a trap is an unsolicited notification sent from a managed device to the management system when a significant event happens. A switch detecting that an interface has gone up or down is a textbook example of the kind of event that can trigger this kind of message.

That is different from normal SNMP polling, where the monitoring server asks the device for status information on a schedule. With a trap, the device does not wait to be asked. It sends the alert immediately, which makes it useful for link failures, threshold violations, and other time-sensitive conditions.

The other choices are related to SNMP, but not in the same way. An object identifier (OID) points to a specific managed value. A string is commonly associated with SNMP community information in older versions. A MIB is the structured database of manageable objects. None of those are the actual alerting mechanism.

Because the question asks for an automatic alert when link status changes, the feature being described is clearly an SNMP trap.

Comprehensive and Detailed Explanation (paraphrased, aligned to N10-009):

An evil twin is a malicious wireless access point that impersonates a legitimate SSID. Once victims connect, the attacker can intercept and manipulate traffic, performing an on-path (man-in-the-middle) attack—capturing credentials, injecting content, or downgrading encryption.

B. DDoS overwhelms services with traffic; it’s not the typical follow-on from clients joining a rogue AP.

C. ARP spoofing is another way to become on-path on wired segments, but with an evil twin, the wireless association itself enables the on-path position.

D. Phishing is social engineering; while an evil twin could be used to present fake portals, the primary technical posture after connection is on-path.

References (CompTIA Network+ N10-009):

Domain: Network Security — Wireless threats (rogue APs/evil twins), traffic interception, on-path attacks.

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When traffic moves laterally between VMs within the same network or subnet, it is known as east-west traffic. This contrasts with north-south traffic, which refers to communication between internal and external networks.

Breakdown of Options:

A. East-west – Correct answer. This refers to traffic between internal servers or VMs, which is a common security concern.

B. Point-to-point – Point-to-point describes a direct connection between two devices, but does not specifically define lateral movement.

C. Horizontal-scaling – This refers to adding more instances or nodes in cloud computing, unrelated to traffic flow.

D. Hub-and-spoke – This network topology describes a centralized design, not lateral traffic.

Understanding TTL (Time to Live):

TTL is a value in a DNS record that tells how long that record should be cached by DNS servers and clients. A higher TTL value means that the record will be cached longer, reducing the load on the DNS server but delaying the propagation of changes.

Impact of TTL on DNS Changes:

When an MX record change is made, it may take time for the change to propagate across all DNS servers due to the TTL setting. If the TTL is high, old DNS information might still be cached, leading to email being directed to the old server.

Best Practice Before Making DNS Changes:

To ensure that changes to DNS records propagate quickly, it is recommended to reduce the TTL value to a lower value (such as 300 seconds or 5 minutes) well in advance of making the changes. This ensures that any cached records will expire quickly, and the new records will be used sooner.

Verification of DNS Changes:

After reducing the TTL and making the change to the MX record, it is important to verify the propagation using tools like dig or nslookup.

Comparison with Other Options:

Change the email client configuration to match the MX record: Email clients generally do not need to match the MX record directly; they usually connect to a specific mail server specified in their settings.

Perform a DNS zone transfer prior to the MX record change: DNS zone transfers are used to replicate DNS records between DNS servers, but they are not related to the propagation of individual record changes.

Update the NS record to reflect the IP address change: NS records specify the DNS servers for a domain and are not related to MX record changes.

RADIUS (Remote Authentication Dial-In User Service) is a networking protocol that provides centralized Authentication, Authorization, and Accounting (AAA) management for users who connect and use a network service. RADIUS is often used to manage access to wireless networks, enabling users to authenticate with their company credentials, ensuring secure access to the network.References: CompTIA Network+ study materials. ​

The correct answer is Active-active because a stock exchange broker requires extremely high availability, minimal downtime, and near-zero data loss. According to CompTIA Network+ (N10-009) objectives under high availability and disaster recovery concepts, an active-active configuration involves multiple systems or sites operating simultaneously and sharing the workload. If one system fails, the other continues processing traffic without service interruption.

This model provides the lowest Recovery Time Objective (RTO) and Recovery Point Objective (RPO), which is critical in financial trading environments where even seconds of downtime can result in major financial loss. Active-active architectures also support load balancing, redundancy, and continuous synchronization between systems.

A warm site (Option A) contains preconfigured hardware but may require data restoration and configuration before becoming fully operational, resulting in some downtime. A full mesh (Option C) is a network topology design and does not specifically address disaster recovery at the service level. In-band (Option D) refers to management traffic sharing the production network and is unrelated to DR strategy.

Therefore, an active-active approach is the most suitable solution for mission-critical financial operations.

Power over Ethernet (PoE) allows devices such as cameras, access points, and VoIP phones to receive both power and data over the same Ethernet cable. If only eight out of twelve cameras turn on, the most likely issue is that the PoE switch has exceeded its power budget (total wattage capacity).

PoE Budget Limitation: PoE switches have a maximum power output, which can limit the number of devices they support simultaneously.

Voltage Check: Different PoE standards exist:

802.3af (PoE): Supplies up to 15.4W per port

802.3at (PoE+): Supplies up to 30W per port

802.3bt (PoE++): Supplies up to 60-100W per port

Power Draw Calculation: If each camera requires 15W and the switch can only provide 120W, then only 8 cameras (8 × 15W = 120W) will turn on.

Incorrect Options:

A. Ethernet Cable Type: Most PoE devices work with Cat5e and above. Cable type could be an issue, but power limitation is the more immediate concern.

C. Transceiver Compatibility: Only relevant if fiber transceivers or modules are in use, but not likely the root cause for power-related issues.

D. DHCP Addressing: DHCP issues affect network connectivity, not power delivery.

Smishing (SMS phishing) occurs when attackers send fraudulent text messages pretending to be a trusted source, tricking the victim into giving up sensitive credentials. Since this came via text message, it qualifies as smishing.

A. DNS poisoning corrupts name resolution.

B. ARP spoofing manipulates MAC-to-IP mappings.

C. Vishing is phishing via voice calls, not text.

References (CompTIA Network+ N10-009):

Domain: Network Security — Social engineering, phishing types (smishing, vishing, spear phishing).

PaaS (Platform as a Service) is best suited for application development because it provides a managed platform that includes the runtime environment, development frameworks, middleware, databases (often), and build/deployment tooling. In a PaaS model, the cloud provider manages the underlying infrastructure (servers, storage, networking, OS patching, and often the application runtime), allowing developers to focus on writing code, testing, and releasing applications quickly. This aligns with Network+ cloud concepts where service models are compared by responsibility: PaaS reduces operational overhead for the customer and accelerates development through standardized environments and automation.

Mobile access is a use case for remote access solutions (VPN, zero trust access, MDM), not specifically PaaS. An e-commerce site could be hosted using many models (IaaS, PaaS, SaaS), so it’s not the most specific match. Cloud-native software describes an architectural style (microservices, containers, managed services) and can be built using PaaS components, but it is broader than a single “use case” and is not as directly tied to the PaaS definition as application development is. Therefore, application development is the clearest and most accurate PaaS use case.

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Quality of Service (QoS) is crucial for real-time services like video conferencing. It prioritizes voice and video packets over less critical traffic (like file downloads), reducing latency, jitter, and packet loss.

B. Network signal may apply to wireless, but it ' s not specific to video issues.

C. Time to live (TTL) affects packet lifespan, not performance or quality.

D. Load balancing manages traffic across multiple paths but doesn’t prioritize real-time traffic like QoS does.

📘 Reference:

CompTIA Network+ N10-009 Official Objectives: 3.6 – Explain the characteristics of network topologies and types.

The option that most directly secures sensitive information on the network is data-in-transit encryption. This ensures that data packets are unreadable to attackers who intercept them while moving across the network. Protocols such as TLS, HTTPS, IPsec, and SSH protect confidentiality and integrity of sensitive information.

B. Principle of least privilege (PoLP) secures access control but does not directly protect data in motion.

C. Role-based access control (RBAC) enforces permissions but again does not secure the data while transmitted.

D. Multifactor authentication (MFA) strengthens identity verification but does not directly protect the data itself once transmitted.

Thus, while all options contribute to overall security, encryption of data-in-transit most directly addresses protection of sensitive information on the network.

References (CompTIA Network+ N10-009):

Domain: Network Security — Encryption methods, confidentiality, data-in-transit protection.