This LFCS practice question tests your understanding of networking. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Exhibit
Refer to the exhibit.
$ tcpdump -i eth0 -c 5 'port 80'
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
11:11:11.111111 IP 10.0.0.1.12345 > 192.168.1.1.80: Flags [S], seq 123, win 29200, options [mss 1460], length 0
11:11:11.222222 IP 192.168.1.1.80 > 10.0.0.1.12345: Flags [S.], seq 456, ack 124, win 28960, options [mss 1460], length 0
11:11:11.333333 IP 10.0.0.1.12345 > 192.168.1.1.80: Flags [.], ack 457, win 29312, length 0
Based on the tcpdump output in the exhibit, what can be concluded about the TCP handshake?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The TCP three-way handshake completed successfully.
The TCP three-way handshake completes successfully when three packets are exchanged: SYN, SYN-ACK, and ACK. The tcpdump output shows exactly these three packets, confirming a successful handshake. The presence of the final ACK from the client to the server's SYN-ACK indicates that the connection is established.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 connection attempt failed because only three packets are shown.
Why it's wrong here
Three packets are normal for a successful handshake.
✗
The connection was reset by the remote host.
Why it's wrong here
No RST flag is present.
✗
The handshake is incomplete because there is no ACK from the server.
Why it's wrong here
The ACK in the third packet is from the client, completing the handshake.
✓
The TCP three-way handshake completed successfully.
Why this is correct
SYN, SYN-ACK, ACK sequence indicates success.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may mistakenly think a three-packet handshake is incomplete or failed, when in fact the TCP three-way handshake is defined as exactly three packets, and the final ACK from the client completes it.
Detailed technical explanation
How to think about this question
The TCP three-way handshake is defined in RFC 793 and uses sequence numbers to synchronize both ends. The client sends a SYN with an initial sequence number (ISN), the server responds with a SYN-ACK that acknowledges the client's ISN and provides its own ISN, and the client sends an ACK to confirm receipt. In real-world scenarios, a successful handshake can be verified by observing the flags in tcpdump output, such as '[S]' for SYN, '[S.]' for SYN-ACK, and '[.]' for ACK.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the LFCS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Networking — This question tests Networking — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The TCP three-way handshake completed successfully. — The TCP three-way handshake completes successfully when three packets are exchanged: SYN, SYN-ACK, and ACK. The tcpdump output shows exactly these three packets, confirming a successful handshake. The presence of the final ACK from the client to the server's SYN-ACK indicates that the connection is established.
What should I do if I get this LFCS question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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