One of the possible causes of slow OS performance, random shutdowns, and loud fan noise is the CPU overheating. This can happen due to dust accumulation, faulty cooling system, or high CPU usage. Overheating can damage the CPU and other components, so it is important to monitor the CPU temperature and take preventive measures.
Reference:
The Official CompTIA A+ Core 1 Student Guide (Exam 220-1101) eBook1, page 2-9, section "CPU Cooling Methods".
The Official CompTIA A+ Core 1 (220-1101) Certification Study Guide2, page 2-11, section "Troubleshooting CPUs".

The most likely explanation for the distorted image on the projector is that the projector's aspect ratio is set incorrectly. The aspect ratio is the ratio of the width to the height of the image, and it affects how the image is displayed on the screen. If the aspect ratio of the projector does not match the aspect ratio of the laptop, the image may appear stretched, squashed, cropped, or letterboxed.
To fix the distorted image, the technician should follow these steps:
Check the aspect ratio of the laptop and the projector. The aspect ratio of the laptop can be found in the display settings of the operating system, such as Windows or Mac OS. The aspect ratio of the projector can be found in the user manual or the on-screen menu of the projector. Common aspect ratios are 4:3, 16:9, and 16:10.
Adjust the aspect ratio of the projector to match the aspect ratio of the laptop. The technician can use the remote control or the buttons on the projector to access the on-screen menu and select the appropriate aspect ratio option. Some projectors may have a dedicated aspect ratio button on the remote control or the projector itself.
Verify that the image is displayed correctly on the screen. The technician can use the zoom, focus, or keystone buttons on the projector or the remote control to fine-tune the image quality and alignment.
Reference:
How to Fix Projector Display Problems - Projectors Tab1
Correcting Distorted Projector Images - Projector Repair World Hyd2
How to Adjust the Aspect Ratio on a Projector - Lifewire

DKIM (DomainKeys Identified Mail) is an email authentication method that attaches a digital signature to outgoing emails to verify the email's authenticity and detect email spoofing.
* SPF (Sender Policy Framework): Specifies which mail servers are authorized to send emails for a domain but does not involve digital signatures.
* DNS Pointer (PTR): Used for reverse DNS lookups, not email authentication.
* MX Records: Specify mail servers for email delivery but do not authenticate emails.
CompTIA A+ Exam Reference: Core 2 (220-1102), Section 2.4, email security and authentication.

The first step in troubleshooting a printer issue is to disconnect the printer power to avoid electric shock or further damage to the printer. The technician can then inspect the fuser and determine if it needs to be replaced or repaired. Installing a printer roller kit or replacing the paper with thicker paper stock will not solve the problem of the overheating fuser. Replacing the fuser without disconnecting the power is dangerous and not recommended. Reference: https://www.comptia.org/certifications/a#examdetails https://www.comptia.org/blog/what-is-a-fuser

802.11 ax is a wireless networking protocol that supports both 2.4GHz and 5GHz devices, as well as backward compatibility with previous 802.11 standards. 802.11 ax offers higher data rates, lower latency, increased capacity, and improved power efficiency than previous protocols. It is also known as Wi-Fi 6 or High Efficiency Wireless (HEW). Reference: https://www.comptia.org/training/books/a-core-1-220-1101-study-guide (page 82)