CompTIA N10-009 Practice Exam Questions & Answers

Explanation

Testing the theory to determine the cause is the troubleshooting step used to strategically eliminate possible causes before confirming the main source of the issue. After the problem is identified and a theory of probable cause is established, the technician must test that theory. If the test confirms the theory, the technician can move toward creating a plan of action. If the theory is not confirmed, the technician should establish a new theory or escalate the issue.

The CompTIA Network+ N10-009 troubleshooting methodology emphasizes a structured process to avoid guessing and unnecessary changes. Testing a theory may include checking configurations, replacing a suspected cable, reviewing logs, verifying connectivity, testing DNS resolution, checking VLAN assignments, or comparing results against known-good systems. This process helps narrow the issue by ruling out causes that do not match the evidence.

Identifying the problem is the first step and involves gathering information. Establishing a theory means forming a likely explanation. Establishing a plan of action happens after the cause is confirmed. Therefore, the step that best matches strategically eliminating known issues is testing the theory to determine the cause.

Explanation

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.

Explanation

A /21 subnet mask means 21 bits are network bits:

8 + 8 + 5 = 21 leaves 11 bits for hosts.

Subnet mask in binary: 11111111.11111111.11111000.00000000

Converted to decimal: 255.255.248.0

Therefore:

A . /19 = 255.255.224.0

B . /20 = 255.255.240.0

C. /21 = 255.255.248.0 correct

D . /22 = 255.255.252.0

Answer correction: The correct option is C. 255.255.248.0, not B.

Reference (CompTIA Network+ N10-009):

Domain: Networking Concepts --- Subnetting, CIDR notation, dotted decimal masks.

Explanation

The most likely cause of buffering issues when moving outdoors is signal degradation. Wireless signals weaken as they travel through obstacles such as walls, glass, and air, leading to weaker connections and reduced data rates.

Breakdown of Options:

A . Network congestion -- While congestion can slow down network speeds, it affects all users, not just those moving outdoors.

B . Wireless interference -- Interference is possible but is more likely caused by other wireless signals rather than outdoor movement.

C . Signal degradation -- Correct answer. Wireless signals weaken with distance and obstacles such as walls, reducing performance.

D . Client disassociation -- Disassociation occurs when clients lose connection to the AP, but the question states that users experience buffering, indicating they are still connected but with a weak signal.

CompTIA Network+ (N10-009) Official Study Guide -- Domain 1.6: Analyze wireless networking technologies.

IEEE 802.11 standards: Wi-Fi propagation characteristics

Explanation

Fax machines use analog phone lines, which are connected using RJ11 connectors. These are standard telephone connectors with 4 or 6 positions and are used for POTS (Plain Old Telephone Service) lines.

F-type is used for coaxial cables (e.g., TV and cable modems).

RJ45 is used for Ethernet network connections.

SC (Subscriber Connector) is used for fiber optic connections, not analog telephone lines.

Reference:

CompTIA Network+ N10-009 Official Objectives: 2.4 -- Compare and contrast common network connectors.

Explanation A Virtual Private Cloud (VPC) is a cloud service feature that allows customers to segment and isolate compute resources, storage, and networking within their cloud account. It creates a private network environment separate from other cloud users. Subnets, security groups, and network ACLs are related tools but VPC is the primary construct for segmentation at the account level.

Explanation

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