DNS stands for Domain Name System, which is a network service that translates hostnames to IP addresses. Hostnames are human-readable names that identify devices or services on the Internet, such as www.google.com or mail.yahoo.com. IP addresses are numerical identifiers that specify the location of devices or services on the Internet, such as 172.217.14.206 or 98.137.11.163. DNS allows users to access websites or services by using hostnames instead of IP addresses, which are easier to remember and type. DNS also allows hostnames to change their IP addresses without affecting the users, which can improve performance and security.
Reference:
What is DNS? | How DNS Works | Cloudflare: This article explains the concept of DNS, its components, its functions, and its benefits.
Hostname vs. IP - address - Stack Overflow: This answer compares the differences between hostnames and IP addresses, and how DNS resolves them.
How DNS Works: Domain Name System(DNS): This article illustrates how DNS works with diagrams and examples.

A sandbox is a virtual environment that isolates the engineer's research activities from the rest of the system. This allows the engineer to test, experiment, and modify the system without affecting the real data, applications, or settings. A sandbox is the best environment for research purposes because it provides a safe and controlled way to explore new ideas, simulate scenarios, and troubleshoot problems. A sandbox can also be easily reset or deleted after the research is done.
Reference
What is a Sandbox Environment?
Chapter 4: Virtualization and Cloud Computing

Explanation
Based on the information recorded by the technician, the network connection appears to be functioning normally. The user's computer is properly configured with an IPv4 address, subnet mask, and default gateway, which should allow the user to access the internet and online videos. The high download and upload speeds and low ping time recorded from the test laptop also indicate that the network is working well. However, the user's inability to watch online videos suggests that there might be an issue with the network card (NIC) on the user's computer. The NIC might be faulty or malfunctioning, which is preventing the computer from receiving and processing the video data. The technician should try replacing the NIC to resolve the issue.

Explanation
UEFI stands for Unified Extensible Firmware Interface, and it is a type of firmware that controls the boot process of a computer. UEFI settings allow the technician to configure various aspects of the boot process, such as the boot order, the boot mode, and the security options. If the technician replaces a laptop hard drive with an M.2 SSD, they may need to adjust the UEFI settings to enable the system to detect and boot from the new drive.

Explanation
The correct answers are A. Identify the location of devices that utilize 2.4GHz and D. Map all of the wireless signals in the restaurant. In order to troubleshoot the issue, the technician should first identify the location of devices that utilize the 2.4GHz frequency, as this can cause interference with the wireless signal. Additionally, the technician should map all of the wireless signals in the restaurant in order to identify any potential sources of interference. Checking to see if the phones are IJTP or STP lines, testing to see if the copper electrical wires are causing interference, verifying T568B is being used in the wiring closet patch panel, and scheduling timed router reboots throughout the day are not necessary steps for troubleshooting this issue.