Explanation
Documenting the lessons learned is the best method for passing along the exact steps other technicians should follow in case the issue arises again. Lessons learned are the knowledge and experience gained from completing a project or solving a problem. Documenting the lessons learned helps to capture the best practices, challenges, solutions, and recommendations for future reference and improvement. Documenting the lessons learned can also help to update the knowledge base, standard operating procedures, or policies related to the issue. References: [CompTIA Network+ Certification Exam Objectives], Lessons Learned: Definition & Examples for Project Managers

127.0.0.1 is the loopback address, it is used to test the functionality of a network card by sending traffic to the card and then verifying that it is received properly. This address is used because it is guaranteed to always point to the local host, regardless of the network configuration. The IP address range for loopback addresses is 127.0.0.0/8.

Explanation
A /30 subnet is the smallest possible subnet that can be used for a point-to-point configuration between two routers. A /30 subnet has only two usable host addresses, one for each router, and a network address and a broadcast address. A /30 subnet conserves IP space by minimizing the number of wasted addresses. A /24, /26, or /28 subnet would have more usable host addresses than needed for a point-to-point configuration and would waste IP space.
References:
Routing Technologies - N10-008 CompTIA Network+ : 2.21
CompTIA Network+ Certification Exam Objectives, page 10

Explanation
A MAC filter list is a security feature that allows or denies access to a wireless network based on the MAC address of the device. A MAC address is a unique identifier assigned to a network interface card (NIC) at the physical layer of the OSI model. However, MAC filtering operates at the data link layer of the OSI model, where MAC addresses are used to encapsulate and deliver data frames between devices on the same network segment.
References: CompTIA Network+ Certification Exam Objectives Version 7.0 (N10-007), Objective 3.1: Given a scenario, install and configure wireless LAN infrastructure and implement the appropriate technologies in support of wireless capable devices.

802.1X is an authentication component that must be used in a network access control (NAC) solution. NAC is a method of enforcing security policies on devices that want to access a network, by verifying their identity, compliance, and authorization. 802.1X is a standard that defines how to provide authentication for devices trying to connect to a LAN or WLAN. It uses the Extensible Authentication Protocol (EAP) to exchange authentication information between the device (supplicant), the network access device (authenticator), and the authentication server (typically RADIUS or TACACS+). 802.1X can prevent unauthorized devices from accessing the network, and can also assign them to different VLANs or apply different policies based on their role or group.
IPSec is a protocol suite that provides encryption, authentication, and integrity for IP packets. It can be used to create secure VPN tunnels between networks or hosts. IPSec is not an authentication component for NAC, but rather a security component for protecting data in transit.
EAP is a framework that supports multiple authentication methods, such as passwords, certificates, tokens, or biometrics. EAP is used by 802.1X to provide authentication for network access, but it is not a component by itself. EAP requires a carrier protocol, such as 802.1X, to transport the authentication messages.
TACACS+ is a protocol that provides authentication, authorization, and accounting (AAA) services for network devices or users. It can be used as an authentication server for 802.1X, but it is not an authentication component for NAC by itself. TACACS+ requires a client-server protocol, such as 802.1X, to communicate with the network access device.
Reference What is 802.1X Network Access Control (NAC)? Compare TACACS + and RADIUS 802.1X: What EXACTLY is it regarding WPA and EAP? CompTIA Network+ Certification All-in-One Exam Guide, Eighth Edition (Exam N10-008)