Explanation
STP stands for Spanning Tree Protocol, which is a network protocol that prevents loops in a switched network by blocking redundant links. STP allows only one active path between any two network devices, and dynamically reconfigures the network topology in case of link failures or changes. STP is essential for proper stability of the network switches, especially when they are cabled in a redundant or complex topology that involves multiple switches and firewalls. Without STP, loops can cause broadcast storms, MAC address table instability, and duplicate frames, which can degrade the network performance and availability. References:
[CompTIA Network+ Certification Exam Objectives], Spanning Tree Protocol (STP) Explained | NetworkLessons.com

Explanation
A denial-of-service (DoS) attack is an example of an attack where an attacker sends more connection requests than a server can handle, causing the server to crash. A DoS attack is a type of cyberattack that aims to disrupt the normal functioning of a network service or resource by overwhelming it with excessive or malformed traffic. A DoS attack can prevent legitimate users from accessing the service or resource, resulting in degraded performance, unavailability, or data loss. A DoS attack can target various network layers, protocols, or components, such as servers, routers, firewalls, or applications. References: [CompTIA Network+ Certification Exam Objectives], What Is a Denial-of-Service (DoS) Attack? | Cisco

Explanation
An extended service set (ESS) is a wireless network that consists of multiple access points (APs) that share the same SSID and are connected by a wired network. An ESS allows wireless clients to roam seamlessly between different APs without losing connectivity. A basic service set (BSS) is a wireless network that consists of a single AP and its associated clients. An independent basic service set (IBSS) is a wireless network that consists of a group of clients that communicate directly without an AP. A unified service set is not a standard term for a wireless network. References:
https://partners.comptia.org/docs/default-source/resources/comptia-network-n10-008-exam-objectives-(2-0),
https://en.wikipedia.org/wiki/Service_set_(802.11_network)

Explanation
PKI stands for Public Key Infrastructure, which is a system of processes, technologies, and policies that allows you to encrypt and sign data using digital certificates1. Digital certificates are issued by Certificate Authorities (CAs) and authenticate the identity of users, devices, or services that communicate online12. Digital certificates also provide the means to encrypt and decrypt messages between sender and receiver using public and private keys2