Installing a host-based content filtering solution on the endpoints ensures that web traffic is filtered locally even when the VPN connection to the on-premises proxy fails, maintaining protection for remote users.
Network access control (A) manages device network access, local gateway configuration (B) does not solve protection if VPN fails, and public NAT (C) exposes internal resources and increases risk.
Endpoint filtering complements VPN for resilient web security, covered in Security Architecture and Operations#6:Chapter 11 CompTIA Security+ Study Guide#.

Comprehensive and Detailed In-Depth Explanation:
Input validation ensures that only properly formatted and expected input is accepted by an application, preventing injection attacks such as SQL injection and command injection. Properly validating and sanitizing user inputs can mitigate these types of attacks.
* Authentication (A) helps verify user identity but does not prevent injection attacks.
* Secure cookies (B) protect session data but do not stop injection-based exploits.
* Static code analysis (C) can help identify vulnerabilities but does not actively prevent injection attacks in real-time.
Implementing strong input validation can prevent malicious code from being executed, reducing the risk of injection attacks.

Validating the code signature is the best way to verify software authenticity, as it ensures that the software has not been tampered with and that it comes from a verified source. Code signatures are digital signatures applied by the software vendor, and validating them confirms the software's integrity and origin.References:
CompTIA Security+ SY0-701 course content and official CompTIA study resources.

Improving security awareness training directly addresses user behavior by teaching employees how to better recognize legitimate emails versus actual phishing attempts. Enhanced training can reduce the number of false positives by helping users more accurately identify true phishing attempts, lowering unnecessary reports and thus help desk workload.
Reference:
CompTIA Security+ SY0-701 Official Study Guide, Domain 5.5: "Improved security awareness training helps reduce false positives in user reporting by teaching users to accurately identify phishing attempts." Exam Objectives 5.5: "Summarize security awareness and training techniques."

The chmod command is used to change file permissions on Unix and Linux systems. If the /etc/shadow file has permissions beyond the baseline recommendation, the systems administrator should use chmod to modify the file's permissions, ensuring it adheres to the security baseline and limits access to authorized users only.
References = CompTIA Security+ SY0-701 study materials, focusing on system hardening and file permissions management.