A VoIP sales call with a customer would be most affected by jitter greater than 10ms on the WAN connection. Jitter is the variation in delay of packets arriving at the destination. It can cause choppy or distorted audio quality for VoIP applications, especially over WAN links that have limited bandwidth and high latency. The recommended jitter for VoIP is less than 10ms. Reference: https://www.voip-info.org/voip-jitter/

Quality of service (QoS) is a mechanism that prioritizes network traffic based on different criteria, such as application type, source and destination address, port number, etc., and allocates bandwidth and resources accordingly. QoS would best improve performance for video conferencing, as it would ensure that video traffic gets higher priority and lower latency than other types of traffic on the network. Packet shaping is a technique that controls the rate or volume of network traffic by delaying or dropping packets that exceed certain thresholds or violate certain policies, which may not improve performance for video conferencing if it causes packet loss or jitter. Port mirroring is a technique that copies traffic from one port to another port on a switch for monitoring or analysis purposes, which does not improve performance for video conferencing at all. Load balancing is a technique that distributes network traffic across multiple servers or devices for improved availability and scalability, which does not

SFTP stands for Secure File Transfer Protocol, which is a network protocol that allows secure and encrypted file transfer over SSH (Secure Shell) connections. SFTP can prevent unauthorized interception or modification of files during transmission, as well as provide authentication and authorization mechanisms for both the client and the server.
FTP, TFTP, and SMTP are not secure protocols, as they do not encrypt the data or the credentials during file transfer. FTP (File Transfer Protocol) and TFTP (Trivial File Transfer Protocol) are used for transferring files between hosts, while SMTP (Simple Mail Transfer Protocol) is used for sending and receiving email messages. These protocols can be easily intercepted, tampered, or spoofed by attackers, compromising the confidentiality, integrity, and availability of the files and the network. Reference:
CompTIA Network+ N10-008 Study Guide, Chapter 4: Network Protocols and Services, p. 173-174 Professor Messer's Network+ N10-008 Course Notes, Section 1.3: Network Services, p. 14 Professor Messer's Network+ N10-008 Video Training Course, 1.3 Network Services - Part 2, 8:00-9:00

A north-south traffic flow is a term used to describe the communication between a user or device outside the network and a server or service inside the network. For example, a public internet user accessing a published web server is a north-south traffic flow. This type of traffic flow typically crosses the network perimeter and requires security measures such as firewalls and VPNs. Reference: CompTIA Network+ N10-008 Certification Study Guide, page 16; The Official CompTIA Network+ Student Guide (Exam N10-008), page 1-9.
North-south traffic flow refers to the flow of traffic between the internal network of an organization and the external world. This type of traffic typically flows from the internet to the organization's internal network, and back again.
Examples of north-south traffic flow include:
A public internet user accessing a published web server
A remote employee connecting to a VPN
An email client sending email to an external server
A customer connecting to an e-commerce website
Reference:
CompTIA Network+ N10-008 Exam Objectives, Version 5.0, August 2022, page 12 CompTIA Network+ Certification Study Guide, Seventh Edition, Todd Lammle, Sybex, 2022, page 17

An extended service set (ESS) is a wireless network that consists of two or more access points (APs) that share the same SSID and are connected by a distribution system, such as a switch or a router. An ESS allows wireless clients to roam seamlessly between different APs without losing connectivity or changing network settings. An ESS can also increase the coverage area and capacity of a wireless network