One of the most common causes of fiber connectivity issues is the reversal of the fibers. This means that the transmit (TX) and receive (RX) ports on one end of the fiber link are not matched with the corresponding ports on the other end. For example, if the TX port on one device is connected to the TX port on another device, and the same for the RX ports, then the devices will not be able to communicate with each other. This can result in no indicator light, no link, or no data transmission12.
To troubleshoot this issue, the technician should first try to reverse the fibers. This can be done by swapping the connectors at one end of the fiber patch cable, or by using a crossover adapter or cable that reverses the polarity of the fibers. The technician should then check if the indicator light comes on and if the devices can communicate properly12.
The other options are not the first steps to troubleshoot this issue. Reterminating the fibers is a time-consuming and costly process that should be done only if there is evidence of physical damage or poor quality of the termination. Verifying the fiber size is not relevant in this scenario, as multimode fiber is compatible with multimode fiber, and any mismatch in core diameter or bandwidth would result in high attenuation, not complete loss of signal. Examining the cable runs for visual faults is a useful technique, but it requires a special tool called a visual fault locator (VFL) that emits a visible red light through the fiber and shows any breaks or bends along the cable. However, a VFL cannot detect polarity issues or connector problems, so it is not sufficient to troubleshoot this issue

Complexity: The password "T5!8j5" appears to be more complex, with a mix of uppercase letters, numbers, and special characters. This complexity increases the strength of the password and makes it more resistant to brute-force attacks.
Length: While longer passwords are generally more secure, in this case, the shorter password
"T5!8j5" is still strong due to its complexity.

MAC address reservation is the technique that allows a device to maintain the same IP address lease based on the physical address of a network card. MAC address reservation is a feature of DHCP that allows network administrators to assign specific IP addresses to specific devices based on their MAC addresses. A MAC address is a unique identifier that is assigned to each network interface card (NIC) by its manufacturer. A MAC address reservation can ensure that a device always receives the same IP address from the DHCP server, regardless of its location or connection time. This can be useful for devices that need consistent network access or configuration, such as servers, printers, or cameras. Reference: [CompTIA Network+ Certification Exam Objectives], How to Reserve IP Addresses with DHCP Server