200-901 Network Fundamentals Practice Question
Which TCP flag is set in the second step of the three-way handshake?
⚠ Common exam trap
Cisco often tests the misconception that the second step uses only an ACK flag, confusing it with the third step where the client sends an ACK to complete the handshake.
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
✓
SYN and ACK
The TCP three-way handshake begins with the client sending a SYN segment to initiate a connection. In the second step, the server responds with a SYN-ACK segment, which both acknowledges the client's SYN (using the ACK flag) and synchronizes its own sequence number (using the SYN flag). This combined flag is essential for establishing a reliable, bidirectional connection.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
ACK
Why it's wrong here
ACK alone is the third step.
- ✓
SYN and ACK
Why this is correct
The server responds with SYN-ACK.
- ✗
SYN
Why it's wrong here
SYN is set in the first step.
- ✗
FIN
Why it's wrong here
FIN is used for connection termination.
Visual reference
Go deeper
Related to this question
About these practice questions
One of 989 original 200-901 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-901 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 200-901 exam.