Geoblocking is the best mitigation technique for unusual network scanning activity coming from a country that the company does not do business with, as it can prevent any potential attacks or data breaches from that country. Geoblocking is the practice of restricting access to websites or services based on geographic location, usually by blocking IP addresses associated with a certain country or region. Geoblocking can help reduce the overall attack surface and protect against malicious actors who may be trying to exploit vulnerabilities or steal information. The other options are not as effective as geoblocking, as they may not block all the possible sources of the scanning activity, or they may not address the root cause of the problem. Official References:
https://www.blumira.com/geoblocking/
https://www.avg.com/en/signal/geo-blocking

Host03 should be patched first, based on the metrics, as it has the highest risk score and the highest number of critical vulnerabilities. The risk score is calculated by multiplying the CVSS score by the exposure factor, which is the percentage of systems that are vulnerable to the exploit. Host03 has a risk score of 10 x 0.9 = 9, which is higher than any other host. Host03 also has 5 critical vulnerabilities, which are the most severe and urgent to fix, as they can allow remote code execution, privilege escalation, or data loss. The other hosts have lower risk scores and lower numbers of critical vulnerabilities, so they can be patched later.

The first thing that must be done when starting an investigation is to secure the scene. Securing the scene involves isolating and protecting the area where the incident occurred, as well as any potential evidence or witnesses. Securing the scene can help prevent any tampering, contamination, or destruction of evidence, as well as any interference or obstruction of the investigation.

Webhooksenable automatic and event-driven interactions between applications. In the context of code repositories and vulnerability scanning, webhooksautomate the scanning processevery time new code is committed. Thisensures continuous security coveragewithout relying on manual triggers, thereby embedding security checks into the development lifecycle efficiently. This automation leads to improved coverage and faster identification of vulnerabilities at the earliest stage possible in the DevSecOps pipeline.
Reference:
Mya Heath,CompTIA CySA+ All-in-One Exam Guide(2024), Chapter 2: "Webhooks are typically automated and allow for real-time data transfer to trigger workflows like vulnerability scans."