Social engineering is a type of testing method that involves manipulating or deceiving people into performing actions or divulging information that can compromise the security of the organization. Social engineering can take various forms, such as phishing, vishing, baiting, quid pro quo, or impersonation. The scenario in the question is an example of a phishing attack, where the intruder sent an email to the user that appeared to be legitimate and contained a malicious link that infected the user's machine and allowed the intruder to access the corporate network. References: [Understanding Cisco Cybersecurity Operations Fundamentals (CBROPS)
- Module 6: Security Incident Investigations]

The IPv4 protocol header contains various fields that provide essential information for routing and delivery of packets across an IP network. Two key pieces of information collected from the IPv4 header are the source IP address and the destination IP address of the packet. These addresses are crucial for identifying where a packet is coming from and where it is intended to go12.

Secure boot and restricting USB ports are two components that can reduce the attack surface on an endpoint.
The attack surface is the sum of all paths for data into and out of the environment. Reducing the attack surface means minimizing the number and complexity of these paths, and thus reducing the opportunities for attackers to exploit vulnerabilities or gain unauthorized access. Secure boot is a feature that ensures that only trusted and verified code can run during the boot process, preventing malware or unauthorized software from compromising the system. Restricting USB ports is a policy that limits the use of USB devices, such as flash drives or external hard drives, that can introduce malware or exfiltrate data from the endpoint.