The errors described - dropped packets and CRC (Cyclic Redundancy Check) errors - often indicate electromagnetic interference (EMI) on unshielded twisted pair (UTP) cabling. The correct replacement is STP (Shielded Twisted Pair), which has shielding that protects signals from external interference, ensuring better reliability in noisy environments such as data centers or near heavy electrical equipment.
A). Coaxial is not used for modern Ethernet server-switch links.
B). Shorter UTP cable does not solve EMI issues.
C). Plenum cable refers to cable jacket type for fire safety, not electrical shielding.
STP cabling reduces interference and ensures reliable gigabit+ Ethernet connections between servers and switches.
References (CompTIA Network+ N10-009):
Domain: Network Troubleshooting - Cabling issues, UTP vs. STP, EMI.

DHCP snooping is a security feature on network switches that helps to prevent unauthorized (rogue) DHCP servers from assigning IP addresses to clients. By implementing DHCP snooping, the network administrator can restrict DHCP responses to authorized servers only, preventing unauthorized DHCP configurations, such as incorrect DNS IPs, from being assigned to clients. This helps prevent man-in-the-middle attacks where malicious actors misconfigure DNS to redirect users to fraudulent sites. (Reference: CompTIA Network+ Study Guide, Chapter on Network Security)

When signal strength is poor, mobile devices constantly boost their transmission power in an attempt to maintain a stable connection. This results in dropped calls/data and rapid battery drain. Since a repeater was installed, misalignment or misconfiguration could be degrading the signal strength.
A). WPS applies to Wi-Fi, not cellular repeaters.
C). Channel frequency might matter for interference, but signal strength is the most direct cause of the described symptoms.
D). Power budget applies to PoE and wired devices, not mobile phones.
References (CompTIA Network+ N10-009):
Domain: Network Troubleshooting - Wireless/cellular troubleshooting, signal strength impact, user symptoms (battery drain, poor connectivity).

*The total number of devices = (150 + 10) users × 2 IPs per user = 320 devices
*Class C (D) supports a maximum of 254 hosts (2^8 - 2), which is too small.
*Class B (B) supports 65,534 hosts (2^16 - 2), making it the best choice.
*Why not the other options?
*Class A (C): Supports millions of addresses, which is overkill for 320 devices.
*Class D (A): Used for multicast, not for device addressing.
Reference:
CompTIA Network+ (N10-009) Official Guide - Chapter 7: IP Addressing and Subnetting

In the CompTIA Network+ (N10-009) troubleshooting methodology, the step that follows verifying full system functionality (confirming the issue is resolved and validating with the user/requirements) is documenting findings, actions, and outcomes. Documentation is a required closing step because it captures what the original symptoms were, what troubleshooting steps were performed, what root cause was identified (if found), what remediation was applied, and what validation confirmed success. This record supports operational continuity by enabling faster resolution if the issue recurs, improving knowledge transfer across teams, and meeting organizational change-control or compliance requirements.
The other options fall in different parts of the methodology. Attempting to replicate the problem is typically performed earlier-after identifying symptoms and before or during isolation-to confirm the issue and help narrow scope. Implementing the plan occurs before verification; you implement the selected solution or escalation plan and then test/verify. Escalating the issue occurs when the technician lacks access, expertise, time, or evidence to proceed, and it can happen during troubleshooting-but it is not the standard step that comes after verifying resolution.