The correct answer is D. Default gateway.
A default gateway is the device that connects a local network to other networks, such as the internet. A default gateway is usually a router or a modem that has an IP address on the same subnet as the local network. A default gateway is necessary for a device to communicate with devices outside its local network.
In this case, the user has a self-configured, static IP address of 192.168.1.20, which belongs to the subnet
192.168.1.0/24 (with a subnet mask of 255.255.255.0). However, the default gateway is set to 192.168.0.1, which belongs to a different subnet (192.168.0.0/24). This means that the user's device cannot reach the default gateway, and therefore cannot connect to the internet.
The technician should edit the default gateway to match the correct subnet of the user's device, such as
192.168.1.1 or 192.168.1.254, depending on the configuration of the network.
Reference: CompTIA A+ Core 1 Sample Questions and Study Guide

VDI (Virtual Desktop Infrastructure) allows users to access a desktop environment that is running on a server in the data center rather than on the local machine. This is particularly useful for employees who need to work remotely on various devices (A), as it provides a consistent and secure environment regardless of the endpoint device. For a bank with security concerns regarding employee activity (D), VDI offers a centralized management of desktops, enhancing security by keeping sensitive data and applications within the data center and not on the local devices, thus reducing the risk of data breaches.
References:
* CompTIA A+ Core 1 Exam Objectives Section 4.2: Summarize aspects of client-side virtualization.

Comprehensive and Detailed In-Depth Explanation:
A common reason for a POST failure after a motherboard installation is improperly seated RAM. The system requires working memory to successfully complete POST. Reseating (removing and reinserting) the RAM ensures it's making proper contact with the motherboard.
* Option A: Flashing the BIOS is not possible if the system won't POST.
* Option B: A dead CMOS battery can cause BIOS settings to reset, but it usually won't prevent POST entirely.
* Option D: Reinstalling the old motherboard is premature - basic troubleshooting steps should be completed first.
CompTIA A+ Core 1 Exam Objective Reference:
* Objective 3.5: Given a scenario, troubleshoot problems related to motherboards, RAM, CPU, and power.

Comprehensive and Detailed In-Depth Explanation:
NFC (Near-Field Communication) operates at very short ranges - usually less than 4cm, and is ideal for quick, secure transactions like contactless payments. Bluetooth supports longer ranges (up to 10 meters or
32 feet) and is suited for ongoing connections like wireless headsets or file transfers.
* Option A: Bluetooth is faster for large file transfers.
* Option B: NFC uses less power, not more.
* Option C: NFC does not require pairing - Bluetooth does.
CompTIA A+ Core 1 Exam Objective Reference:
* Objective 1.5: Given a scenario, connect and configure accessories and ports of mobile devices.

SSH (Secure Shell) encrypts data communications for secure remote login and management of network devices, ensuring all console connections are encrypted.
Why Not B (LDAP): LDAP is used for directory services and does not encrypt by default.
Why Not C (FTPS): FTPS encrypts file transfers, not console communications.
Why Not D (SMTP): SMTP is used for email transmission, not for securing login sessions.
CompTIA A+ Exam Reference: Core 1 (220-1101), Section 2.7, network security protocols.