200-201 Security Concepts Practice Question
A network analyst notices a high volume of traffic from a single external IP address to multiple internal hosts on port 443. The traffic includes incomplete TCP handshakes. Which type of reconnaissance is being performed?
⚠ Common exam trap
200-201 often tests the distinction between active reconnaissance (scanning, generates traffic) and passive reconnaissance (WHOIS, DNS, no target traffic) — candidates confuse the two when they see 'reconnaissance' in the question.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Active reconnaissance via port scanning
A high volume of connections to port 443 with incomplete TCP handshakes (SYN sent, no ACK) from one external IP to many internal hosts is the signature of a TCP SYN scan — an active reconnaissance technique used to discover which hosts and ports are open. The incomplete handshakes occur because the scanner does not complete the three-way handshake, either to avoid logging or to speed up the scan.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Social engineering attack
Why it's wrong here
Social engineering manipulates people into divulging information through phishing, pretexting or baiting; it produces no network scanning traffic or half-open TCP connections. It is tempting because reconnaissance often includes human targeting, and social engineering is a recognised precursor to attack — but the packet-level evidence here is technical scanning, not human interaction.
- ✓
Active reconnaissance via port scanning
Why this is correct
Incomplete TCP handshakes across many internal hosts on port 443 indicate a SYN scan probing for live services. This is active reconnaissance: the attacker sends packets directly to targets, unlike passive monitoring, and the half-open connections reveal port scanning behaviour.
- ✗
Denial of Service attack
Why it's wrong here
A denial of service attack aims to exhaust resources and disrupt availability, typically using completed connections or floods rather than incomplete handshakes across many hosts. It is tempting because high-volume traffic from one source resembles a flood, but incomplete TCP handshakes to multiple internal hosts on port 443 indicate port scanning reconnaissance.
- ✗
Passive reconnaissance using WHOIS
Why it's wrong here
WHOIS queries registry databases for domain ownership records; it generates no traffic to internal hosts and no TCP handshakes. It is tempting because passive reconnaissance gathers information without direct target contact, and WHOIS is a legitimate passive technique — but the observed port 443 scanning with incomplete handshakes is active reconnaissance.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 200-201 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-201 exam.