Software-defined networking (SDN) enables microsegmentation by allowing administrators to create fine- grained, dynamic network segments at the software layer independent of physical network topology. This capability isolates workloads and controls traffic flows between segments, enhancing security within data centers and cloud environments.
Next-generation firewalls (A) provide advanced filtering and inspection but do not inherently deliver the granular segmentation flexibility of SDN. Embedded systems (C) and air-gapped systems (D) refer to specific hardware or physical isolation techniques but do not implement microsegmentation as a network control method.
The concept of microsegmentation through SDN is detailed in the Security Architecture domain of the SY0-
701 exam#6:Chapter 3 CompTIA Security+ Study Guide#.

A high-availability network is a network that is designed to minimize downtime and ensure continuous operation of critical services and applications. To achieve this goal, a high-availability network must consider two important factors: ease of recovery and attack surface.
Ease of recovery refers to the ability of a network to quickly restore normal functionality after a failure, disruption, or disaster. A high-availability network should have mechanisms such as redundancy, failover, backup, and restore to ensure that any single point of failure does not cause a complete network outage. A high-availability network should also have procedures and policies for incident response, disaster recovery, and business continuity to minimize the impact of any network issue on the organization's operations and reputation.
Attack surface refers to the exposure of a network to potential threats and vulnerabilities. A high-availability network should have measures such as encryption, authentication, authorization, firewall, intrusion detection and prevention, and patch management to protect the network from unauthorized access, data breaches, malware, denial-of-service attacks, and other cyberattacks. A high-availability network should also have processes and tools for risk assessment, threat intelligence, vulnerability scanning, and penetration testing to identify and mitigate any weaknesses or gaps in the network security.
References: CompTIA Security+ Study Guide: Exam SY0-701, 9th Edition, Chapter 4: Architecture and Design, pages 164-1651. CompTIA Security+ Certification Kit: Exam SY0-701, 7th Edition, Chapter 4:
Architecture and Design, pages 164-1652.

= SQL injection is a type of attack that enables the use of an input field to run commands that can view or manipulate data in a database. SQL stands for Structured Query Language, which is a language used to communicate with databases. By injecting malicious SQL statements into an input field, an attacker can bypass authentication, access sensitive information, modify or delete data, or execute commands on the server. SQL injection is one of the most common and dangerous web application vulnerabilities. References = CompTIA Security+ Study Guide with over 500 Practice Test Questions: Exam SY0-701, 9th Edition, Chapter 5, page 195. CompTIA Security+ SY0-701 Exam Objectives, Domain 1.1, page 8.

Recovery Point Objective (RPO) defines the maximum acceptable amount of data loss measured in time. It directly impacts how frequently backups should occur to ensure data can be restored to a point no older than the RPO after a disruption.
Recovery Time Objective (RTO) (A) defines how quickly systems must be restored but does not dictate backup frequency. Mean Time To Repair (MTTR) (C) and Mean Time Between Failures (MTBF) (D) relate to system repair and reliability metrics, not backup schedules.
Understanding and defining RPO is a key part of the Business Impact Analysis (BIA) process covered in the Risk Management domain#6:Chapter 17 CompTIA Security+ Study Guide#.