The correct answer is that the cable length exceeds the supported distance for 16 Gbps Fibre Channel. At 16 Gbps, signal integrity degrades sharply over long distances, causing bit errors that the MDS switch detects as CRC errors on the F port. This degradation becomes more pronounced with large I/O because longer frames have a higher probability of containing corrupted bits, making the error count spike under heavy workloads. On the Cisco DCCOR and CCNP Data Center Core 350-601 exam, this scenario tests your understanding of physical-layer limitations in high-speed SAN designs, often appearing as a trap where candidates blame transceivers or SFP failures instead of distance. Remember that for 16 Gbps FC, OM3 multimode fiber supports only about 10 meters, while OM4 extends to roughly 100 meters—exceeding these limits directly causes CRC errors. A simple memory tip: “16 Gbps, 16 meters? No—check the OM3/OM4 spec before blaming the SFP.”
350-601 Storage Network Practice Question
This 350-601 practice question tests your understanding of storage network. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
An engineer is troubleshooting a SAN performance issue. The MDS switch shows high CRC errors on an F port. The host is connected via a 16 Gbps FC link. The errors increase when the host sends large I/O. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The cable length exceeds the supported distance for 16 Gbps.
At 16 Gbps Fibre Channel, signal integrity degrades over long cable distances, causing bit errors that manifest as CRC errors on the F port. The error increase with large I/O is characteristic of marginal signal quality, as larger frames are more likely to encounter corrupted bits. Option E correctly identifies that the cable length exceeds the supported distance for 16 Gbps, typically 10 meters for OM3 multimode fiber or 100 meters for OM4, depending on the transceiver type.
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 host's HBA firmware is outdated.
Why it's wrong here
Firmware issues can cause problems but typically not exclusively CRC errors on the switch side.
✗
The zone configuration is incorrect.
Why it's wrong here
Incorrect zoning prevents communication but does not cause CRC errors.
✗
The host is experiencing buffer credit starvation.
Why it's wrong here
Buffer credit starvation results in discards (credit loss), not CRC errors.
✗
The switch port is configured for 8 Gbps.
Why it's wrong here
Speed mismatch would cause link issues but not necessarily CRC errors.
✓
The cable length exceeds the supported distance for 16 Gbps.
Why this is correct
16 Gbps FC has shorter reach; long cables cause CRC errors, especially under heavy load.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between physical-layer errors (CRC, running disparity) and higher-layer issues (buffer credits, zoning), so the trap here is that candidates confuse buffer credit starvation (a flow-control problem) with CRC errors (a signal-integrity problem).
Detailed technical explanation
How to think about this question
CRC errors in Fibre Channel are calculated over the entire frame (excluding SOF and EOF) using a 32-bit CRC polynomial (IEEE 802.3). At higher speeds like 16 Gbps, the bit period is shorter (approximately 62.5 ps), making the link more sensitive to dispersion and attenuation. The 'show interface fc' command on MDS switches displays CRC error counters, and the 'show interface fc <interface> transceiver details' command can reveal optical power levels that may be marginal.
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 350-601 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.
Storage Network — This question tests Storage Network — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The cable length exceeds the supported distance for 16 Gbps. — At 16 Gbps Fibre Channel, signal integrity degrades over long cable distances, causing bit errors that manifest as CRC errors on the F port. The error increase with large I/O is characteristic of marginal signal quality, as larger frames are more likely to encounter corrupted bits. Option E correctly identifies that the cable length exceeds the supported distance for 16 Gbps, typically 10 meters for OM3 multimode fiber or 100 meters for OM4, depending on the transceiver type.
What should I do if I get this 350-601 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Refer to the exhibit. The interface shows CRC errors. What is the most likely cause of these errors?
medium
A.Insufficient buffer credits for the distance.
B.The port is configured as F port but should be E port.
C.Speed mismatch between the ports.
✓ D.Faulty SFP or fiber cable.
Why D: CRC errors often indicate physical layer issues such as optics or cable problems. Option B is correct. Option A is wrong because credit starvation would show credit timeouts. Option C is wrong because speed mismatch would cause link failures. Option D is wrong because the port is operational mode F.
Last reviewed: Jun 24, 2026
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