Passive reconnaissance involves collecting information through which of the following?

Social engineering involves actively contacting and psychologically manipulating individuals to extract information, which constitutes active reconnaissance because it requires direct human-to-human interaction with the target organization.

Network traffic sniffing requires physical or logical presence on or adjacent to the target network to capture live packets, making it an active or semi-active technique that involves direct interaction with the target environment.

Man-in-the-middle attacks require actively intercepting and relaying live communications between parties, making them an active attack technique rather than a passive information-gathering method.

Passive reconnaissance involves collecting information about a target through publicly available sources such as WHOIS records, DNS lookups, search engines, social media, company websites, job postings, and public databases - none of which require sending traffic to or interacting with the target's systems. This approach generates no logs or alerts on the target's IDS or firewalls, making it completely undetectable. Tools and techniques such as Google dorking, Shodan searches, and reviewing public corporate filings are classic examples of passive reconnaissance.