N10-009 CompTIA Network+ Certification Exam Free Practice Exam Questions (2026 Updated)

The problem is a subnet mismatch . The web server is using 255.255.255.0 , which places it in the 192.168.1.0/24 network. The database server is using 255.255.255.128 , which places 192.168.1.201 in the 192.168.1.128/25 network. So even though both addresses begin with 192.168.1, the two systems are not treating the network boundaries the same way.

That creates a Layer 3 communication issue because one host may believe the other device is local while the other host may treat traffic differently based on its smaller subnet. In a normal server segment like this, both systems should agree on the same mask if they are intended to be on the same network.

Changing the database server’s subnet mask to 255.255.255.0 fixes that inconsistency immediately. Then both servers and the firewall interface are using the same local network definition, and traffic can be handled properly.

The other options do not solve the real issue. Changing the firewall to /25 would break consistency for the rest of the segment. Pointing the database server to 1.2.3.4 is incorrect because that is outside the local subnet and appears to be an upstream route. Changing the IP to 192.168.1.150 still leaves the wrong mask in place. The clean fix is A .

The best solution here is band steering. Band steering allows modern wireless access points to automatically direct dual-band capable clients toward the 5 GHz band instead of the crowded 2.4 GHz band. The 5 GHz band has more available non-overlapping channels and can provide faster speeds with less interference, especially in dense environments. Devices that only support 2.4 GHz will remain on that band, while compatible devices enjoy the improved performance of 5 GHz.

A. 802.1X is a port-based network access control method for authentication. While important for security, it does not affect wireless channel utilization or client throughput.

B. MIMO (Multiple Input, Multiple Output) is a technology that improves throughput by using multiple antennas to send/receive simultaneously, but it does not actively steer clients between frequency bands.

C. ESSID (Extended Service Set Identifier) is just the network name for a set of APs in the same WLAN; it has no role in optimizing performance by band.

By implementing band steering, administrators reduce channel overlap on the 2.4 GHz band, improve spectral efficiency, and provide higher performance to capable devices, directly meeting the requirements described in the scenario.

References (CompTIA Network+ N10-009):

Domain: Networking Concepts — Wireless optimization, band steering, dual-band client management.

The Network layer (Layer 3 of the OSI model) can utilize the connectionless protocol IP (Internet Protocol) to send data packets independently without establishing a connection. This approach is typical for protocols like IP, which provide best-effort delivery rather than guaranteed delivery. The document explains:

“The OSI Network Layer is responsible for logical addressing and routing, and it can utilize connectionless protocols like IP to send packets without requiring a session setup. This layer does not guarantee packet delivery, relying on higher layers for error detection or correction if needed.”

The netstat command provides information about network connections, routing tables, interface statistics, masquerade connections, and multicast memberships. Running netstat on the server can help the administrator verify that the web server process is listening on the expected port (e.g., port 80 for HTTP or port 443 for HTTPS) and that there are no issues with network connections. This is a crucial first step in diagnosing why the web server is not accessible via a browser.References: CompTIA Network+ study materials. ​

802.1X is a port-based Network Access Control (NAC) method that enforces authentication before allowing access to the network. It uses a RADIUS server for identity verification and policy enforcement, ensuring only authorized users/devices gain access.

A. Standard ACL filters traffic by IP, not identity.

B. MAC filtering controls devices by hardware address but can be spoofed.

D. SSO (Single Sign-On) provides user convenience across services, not network-level access control.

References (CompTIA Network+ N10-009):

Domain: Network Security — NAC, 802.1X authentication, identity-based access.

The correct answer is IP address blocks because geofencing policies typically rely on public IP address ranges associated with specific geographic regions or countries. According to CompTIA Network+ (N10-009) security objectives, geofencing is a security control used to restrict or allow traffic based on geographic location. This is commonly implemented on firewalls, VPN concentrators, or security gateways by referencing databases that map IP address blocks to countries or regions.

When configuring geofencing, administrators create access control rules that permit or deny traffic from specific country-based IP ranges. This method is effective for limiting remote access to approved geographic locations and reducing exposure to international threat sources.

MAC filtering (Option A) is used within local networks and does not function over the internet for geographic control. Administrative distance (Option B) is a routing concept that determines route preference and has no relation to access control policies. Bluetooth beacon signals (Option C) are used for proximity-based services and indoor positioning, not for country-level remote access restrictions.

Therefore, leveraging IP address blocks is the correct approach for implementing geofencing controls.

Definition of Fiber Connector Types:

LC (Lucent Connector): A small form-factor fiber optic connector with a push-pull latching mechanism, commonly used for high-density applications.

SC (Subscriber Connector or Standard Connector): A larger form-factor connector with a push-pull latching mechanism, often used in datacom and telecom applications.

ST (Straight Tip): A bayonet-style connector, typically used in multimode fiber optic networks.

MPO (Multi-fiber Push On): A connector designed to support multiple fibers (typically 12 or 24 fibers), used in high-density cabling environments.

Common Usage:

LC Connectors: Due to their small size, LC connectors are widely used in network interface cards (NICs) and high-density environments such as data centers. They allow for more connections in a smaller space compared to SC and ST connectors.

SC and ST Connectors: These are larger and more commonly used in patch panels and older fiber installations but are less suitable for high-density applications.

MPO Connectors: Primarily used for trunk cables in data centers and high-density applications but not typically on individual network interface cards.

Selection Criteria:

The small form-factor and high-density capabilities of LC connectors make them the preferred choice for network interface cards, where space and connection density are critical considerations.

A UPS (Uninterruptible Power Supply) provides backup power to devices during a power outage, allowing for continuous operation and protecting against sudden shutdowns that could cause data loss or equipment damage. The document confirms:

“A UPS (Uninterruptible Power Supply) is essential for maintaining power to critical devices during an outage, protecting data and ensuring continuous operation until power is restored or a safe shutdown can be performed.”

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 most likely issue is a duplex mismatch, which is a well-documented cause of collisions and poor network performance, as outlined in the CompTIA Network+ N10-009 troubleshooting objectives. A duplex mismatch occurs when one end of a network link is configured for full duplex while the other end is operating in half duplex. In half-duplex mode, devices must take turns transmitting and receiving data, which inherently allows for collisions. When paired with a full-duplex device—which expects simultaneous send and receive—collisions and retransmissions occur frequently.

The presence of collisions on a switch interface is a key diagnostic clue. Modern Ethernet switches operating correctly in full duplex should not experience collisions at all. When collisions are observed, it almost always points to a duplex configuration issue, often caused by manual speed/duplex settings on one device and auto-negotiation on the other.

A wrong speed setting may prevent link establishment entirely or cause errors, but it does not typically result in collisions. Jumbo frames can cause packet drops or fragmentation issues, not collisions. An incorrect VLAN configuration affects logical segmentation and connectivity but operates at Layer 2 and does not generate collisions.

CompTIA Network+ emphasizes duplex mismatch as a classic and frequently tested troubleshooting scenario. Correcting it—usually by enabling auto-negotiation on both ends—restores normal, collision-free communication.

A rogue DHCP server occurs when an unauthorized or misconfigured DHCP server assigns incorrect IP addresses, default gateways, or DNS settings to clients.

•In this scenario:

•The user can ping the gateway, meaning local network communication is working.

•However, they cannot access network resources, which suggests incorrect IP configuration (likely due to a rogue DHCP server assigning the wrong gateway or DNS).

•Why not the other options?

•VLAN hopping (A): This is an attack that exploits VLAN configurations to gain access to unauthorized VLANs. It would not typically cause multiple users to lose network access.

•Distributed DoS (C): A DDoS attack floods a network or service with traffic, but this issue is more likely misconfigured IP settings than an actual attack.

•Evil twin (D): This refers to a fraudulent Wi-Fi network mimicking a legitimate one. Since the users are on a wired network (ipconfig output checked), this is not applicable.

If a switch has port security enabled (such as sticky MAC or a configured allowed MAC), the port will only allow the original NIC’s MAC address. When a new NIC with a different MAC address is installed, the port rejects traffic, preventing network connectivity.

B. BPDU guard protects against rogue switches, not end hosts.

C. Link aggregation applies when bundling multiple uplinks, not a single PC connection.

D. PoE budget applies to powered devices like APs, not PCs.

References (CompTIA Network+ N10-009):

Domain: Network Troubleshooting — Port security, MAC address filtering, switch security features.

The correct answer is ACL (Access Control List). According to the CompTIA Network+ N10-009 objectives, ACLs are a fundamental and cost-effective method for controlling traffic flow at routers and firewalls. An ACL allows administrators to permit or deny traffic based on source IP address, destination IP address, protocol, or port number.

In this scenario, the suspicious traffic is identified as originating from a specific unknown foreign IP address. The most direct and economical mitigation strategy is to configure an ACL rule that denies traffic from that specific IP address (or subnet) at the network perimeter. This approach leverages existing network infrastructure without requiring additional hardware or licensing costs.

An IDS (Intrusion Detection System) monitors and alerts on malicious activity but does not actively block traffic unless paired with IPS functionality, and it may involve additional cost and complexity. NAT is used for address translation and does not provide traffic filtering based on threat intelligence. DoS prevention solutions are typically more advanced, specialized, and costly, often intended for large-scale distributed denial-of-service attacks rather than blocking traffic from a single suspicious IP.

The Network+ objectives emphasize implementing layered security controls, starting with simple and effective measures. In this case, applying an ACL at the firewall or router is the most cost-efficient and immediate method to mitigate the identified threat.

The channel width (20 MHz vs. 40 MHz vs. 80 MHz) directly impacts Wi-Fi throughput. If the AP is configured with a narrow channel width (e.g., 20 MHz), maximum data rates will be significantly lower than other APs using wider channels (e.g., 80 MHz). This matches the scenario where one AP achieves only ~75 Mbps, while others reach 500 Mbps.

B. DNS issues affect name resolution, not raw throughput.

C. Authentication failure would prevent connection, not reduce throughput.

D. DHCP issues would prevent obtaining an IP, not cause slower speeds.

References (CompTIA Network+ N10-009):

Domain: Network Troubleshooting — Wireless throughput issues, channel width configuration.

Definition of Jumbo Frames:

Jumbo frames are Ethernet frames with more than 1500 bytes of payload, typically up to 9000 bytes. They are used to improve network performance by reducing the overhead caused by smaller frames.

Why Switches Support Jumbo Frames:

Switches are network devices designed to manage data packets and can be configured to support jumbo frames. This capability enhances throughput and efficiency, particularly in high-performance networks and data centers.

Incompatibility of Other Devices:

Access Point: Primarily handles wireless communications and does not typically support jumbo frames.

Bridge: Connects different network segments but usually operates at standard Ethernet frame sizes.

Hub: A simple network device that transmits packets to all ports without distinguishing between devices, incapable of handling jumbo frames.

Practical Application:

Enabling jumbo frames on switches helps in environments where large data transfers are common, such as in storage area networks (SANs) or large-scale virtualized environments.

Cross talk can often be caused by improper termination of cables. The first step in troubleshooting should be to inspect the connectors for any wires that might be touching or exposed. Ensuring that all wires are correctly seated and that no conductors are exposed can help reduce or eliminate cross talk. This step should be taken before attempting to re-terminate the connections or check for other sources of interference.References: CompTIA Network+ study materials.

An on-path attack (formerly known as a man-in-the-middle (MITM) attack) involves intercepting and potentially altering communications between two parties without their knowledge. This can be done via techniques like ARP poisoning, rogue access points, or SSL stripping.

Breakdown of Options:

A. Self-signed certificate – These are untrusted SSL certificates but do not intercept traffic.

B. VLAN hopping – VLAN hopping exploits VLAN misconfigurations but does not necessarily intercept communications.

C. On-path attack – Correct answer. This intercepts and modifies traffic between two endpoints.

D. Phishing – Phishing tricks users into revealing credentials rather than intercepting network traffic.

Definition of MAC Flooding:

MAC flooding is an attack where a malicious actor sends numerous fake MAC addresses to a switch, overwhelming its CAM table. The CAM table stores MAC addresses and their associated ports for efficient traffic forwarding.

Impact of MAC Flooding:

CAM Table Overflow: When the CAM table is full, the switch cannot learn new MAC addresses and is forced to broadcast traffic to all ports, leading to a degraded network performance and potential data interception.

Switch Behavior: The switch operates in a fail-open mode, treating the network as a hub, which can be exploited for eavesdropping on traffic.

Comparison with Other Attacks:

ARP Spoofing: Involves sending false ARP (Address Resolution Protocol) messages to associate the attacker ' s MAC address with the IP address of another device.

Evil Twin: Involves creating a rogue wireless access point that mimics a legitimate one to intercept data.

DNS Poisoning: Involves corrupting the DNS cache with false information to redirect traffic to malicious sites.

Preventive Measures:

Port Security: Configure port security on switches to limit the number of MAC addresses per port, preventing CAM table overflow.

Network Segmentation: Use VLANs to segment network traffic and limit the impact of such attacks.