Cybersecurity-Apprentice Network Fundamentals Practice Question
A security analyst is examining a packet capture (PCAP) and observes that the TCP window size is dropping to zero during a data transfer between a client and a server through the firewall. What does a zero window size typically indicate in a TCP transmission?
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
✓
The receiver's buffer is full and it is requesting the sender to pause transmission.
A TCP zero window size indicates that the receiver's buffer is full and it cannot currently accept any more data, temporarily pausing transmission.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The maximum segment size (MSS) negotiation has failed during the three-way handshake.
Why it's wrong here
MSS negotiation failure typically leads to fragmentation issues or connection drops, not a zero window state during data transfer.
- ✓
The receiver's buffer is full and it is requesting the sender to pause transmission.
Why this is correct
The TCP window size field informs the sender how many bytes the receiver can accept; zero means the buffer is full.
- ✗
An asymmetric routing loop has caused sequence numbers to go out of sync.
Why it's wrong here
Asymmetric routing causes out-of-order packets or missing SYNs, not a zero window size condition.
- ✗
The firewall has blocked the session due to a security profile match.
Why it's wrong here
A security block results in a TCP reset or dropped packets, not a managed zero window size notification from the receiver.
About these practice questions
One of 177 original Cybersecurity-Apprentice 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 and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official Palo Alto Networks exam blueprint
This Cybersecurity-Apprentice practice question is part of Courseiva's free Palo Alto Networks 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 Cybersecurity-Apprentice exam.