The correct actions are to replace the fiber optic cable and SFP, and to enable BB_credit recovery on the interface. CRC errors on a Fibre Channel interface in a Cisco MDS environment almost always point to physical-layer degradation—faulty cabling, damaged SFPs, or dirty connectors cause bit errors that accumulate as CRC increments. Enabling BB_credit recovery addresses a less obvious but related cause: buffer credit starvation can mimic CRC symptoms by forcing frame retransmissions, so this feature dynamically adjusts credits to prevent performance loss. On the Cisco DCCOR 350-601 exam, this question tests your ability to differentiate between true physical faults and flow-control issues; a common trap is to immediately blame the storage array or assume a software bug. Remember the memory tip: “Cable and credit—fix the bits, then fix the flow.”
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 performance issue on a Cisco MDS 9700 switch. The 'show interface fc1/1' output shows CRC errors incrementing slowly. The interface is connected to a storage array. Which two actions should the engineer take to resolve the issue?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Replace the fiber optic cable and SFP.
CRC errors on a Fibre Channel interface typically indicate physical-layer issues such as faulty cabling, damaged SFPs, or dirty optical connectors. Replacing the fiber optic cable and SFP (Option B) directly addresses the most common root cause of CRC errors. Additionally, enabling BB_credit recovery (Option C) helps mitigate performance degradation caused by buffer credit starvation, which can manifest as CRC-like symptoms in some scenarios.
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.
Faulty cables or SFPs are common causes of CRC errors.
Related concept
Read the scenario before looking for a memorised answer.
✓
Enable BB_credit recovery on the interface.
Why this is correct
BB_credit recovery helps manage buffer credit issues that can cause CRC errors.
Related concept
Read the scenario before looking for a memorised answer.
✗
Clear the interface counters.
Why it's wrong here
Clearing counters hides the problem without resolving it.
✗
Change the interface speed from auto to a fixed value.
Why it's wrong here
Speed mismatch is less likely; fixing speed may cause other issues.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between physical-layer errors (CRC) and flow-control issues (BB_credit), tempting candidates to choose a single answer when both a physical fix and a protocol-level tuning are required.
Detailed technical explanation
How to think about this question
CRC errors in Fibre Channel are detected at the frame level using a 32-bit CRC (FC-FS-4). They often result from signal degradation due to attenuation, dirty connectors, or faulty transceivers. BB_credit recovery (enabled via 'flowcontrol credit recovery') is a mechanism that dynamically adjusts buffer credits to prevent performance drops when the remote end is slow to return credits, which can reduce frame retransmissions and associated CRC-like errors in congested links.
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: Replace the fiber optic cable and SFP. — CRC errors on a Fibre Channel interface typically indicate physical-layer issues such as faulty cabling, damaged SFPs, or dirty optical connectors. Replacing the fiber optic cable and SFP (Option B) directly addresses the most common root cause of CRC errors. Additionally, enabling BB_credit recovery (Option C) helps mitigate performance degradation caused by buffer credit starvation, which can manifest as CRC-like symptoms in some scenarios.
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.
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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