The correct next step is to check that the PFC configuration matches on both ends and that PFC is enabled on the FCoE VLAN interfaces. This is because Priority Flow Control must be consistently applied on every hop of an FCoE link to guarantee lossless behavior for storage traffic; if PFC is enabled for CoS 3 on the upstream switch but not on the server’s vNIC or the FCoE VLAN interfaces, the lack of pause frames will cause intermittent frame drops and periodic timeouts, even when the FCoE VLAN itself shows no errors. On the Cisco DCCOR and CCNP Data Center Core 350-601 exam, this scenario tests your understanding that FCoE relies on a lossless fabric—PFC misconfiguration is a classic trap where engineers focus on VLAN errors instead of verifying end-to-end DCB consistency. A useful memory tip is “PFC must be peer-to-peer”: if one side pauses and the other doesn’t, frames get dropped silently, so always confirm both ends of the link and all intermediate interfaces have PFC enabled for the same CoS value.
350-601 Storage Network Practice Question
This 350-601 practice question tests your understanding of storage network. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
During an FCoE deployment, the server team reports that hosts can reach the storage array but performance is intermittent with periodic timeouts. The network team sees no errors on the FCoE VLAN. The DCB configuration on the upstream switch shows that PFC is enabled for CoS 3. What should the engineer check next?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Check if the PFC configuration matches on both ends and that PFC is enabled on the FCoE VLAN interfaces
D is correct because PFC (Priority Flow Control) must be consistently configured on both ends of an FCoE link to prevent frame loss. If PFC is enabled for CoS 3 on the upstream switch but not on the server's vNIC or the FCoE VLAN interfaces, the lack of lossless behavior causes intermittent timeouts and performance degradation, even if the FCoE VLAN shows no errors.
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.
✗
Verify that jumbo frames are enabled on the storage array
Why it's wrong here
Jumbo frames are typically required but would cause errors if missing.
✗
Confirm that the VSAN is appropriately sized for the number of hosts
Why it's wrong here
VSAN size rarely causes intermittent timeouts.
✗
Ensure that the FCoE VLAN is enabled for FCoE on the server's vNIC
Why it's wrong here
If hosts can reach storage, FCoE VLAN is already enabled.
✓
Check if the PFC configuration matches on both ends and that PFC is enabled on the FCoE VLAN interfaces
Why this is correct
PFC must be consistent across all hops.
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 misconception that FCoE performance issues are due to VLAN or VSAN misconfiguration, when the real culprit is mismatched PFC settings between endpoints.
Detailed technical explanation
How to think about this question
PFC uses IEEE 802.1Qbb to create lossless links by pausing traffic on a per-CoS basis; for FCoE, CoS 3 is the default priority for FCoE traffic. If PFC is misaligned (e.g., enabled on the switch but not on the server NIC), the switch may drop frames when buffers fill, causing FC-level timeouts. A common verification command is 'show interface priority-flow-control' on both the switch and the server's converged network adapter.
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 help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
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: Check if the PFC configuration matches on both ends and that PFC is enabled on the FCoE VLAN interfaces — D is correct because PFC (Priority Flow Control) must be consistently configured on both ends of an FCoE link to prevent frame loss. If PFC is enabled for CoS 3 on the upstream switch but not on the server's vNIC or the FCoE VLAN interfaces, the lack of lossless behavior causes intermittent timeouts and performance degradation, even if the FCoE VLAN shows no errors.
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.
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. Which THREE factors should be considered when designing an FCoE SAN to avoid traffic loss? (Choose three.)
hard
A.Use standard Ethernet cut-through switching for all FCoE traffic.
✓ B.Enable priority flow control (PFC) on all FCoE-enabled interfaces.
✓ C.Use a dedicated FCoE VLAN that is not used for any other traffic.
D.Disable the FIP snooping feature to reduce latency.
✓ E.Ensure that the FCoE Maximum Transmission Unit (MTU) is set to 2500 bytes.
Why B: Options A, B, D are correct. C and E are incorrect.
Variation 2. A network engineer is deploying FCoE in a top-of-rack design. Which statement about the required lossless Ethernet fabric is correct?
medium
A.Data Center Bridging Exchange (DCBX) automatically enables PFC when FCoE is configured
B.FCoE uses VLAN 1002 by default for all traffic
C.FCoE frames are limited to 1500 bytes to avoid fragmentation
✓ D.Priority Flow Control (PFC) must be enabled to create lossless CoS
Why D: Option A is correct: Priority Flow Control (PFC) is mandatory for FCoE to ensure no frames are dropped due to congestion. Option B is wrong because DCBX is used to negotiate PFC, but PFC itself is the mechanism. Option C is wrong: FCoE uses a dedicated VLAN (typically 1002–1003 but can be assigned). Option D is wrong: FCoE maximum frame size is 2240 bytes (or 2500 with jumbo).
Variation 3. Refer to the exhibit. An engineer is troubleshooting poor FCoE performance. The exhibit shows output from the FCoE interface. Which observation indicates a potential issue?
hard
✓ A.PFC frames received is high compared to PFC frames sent
B.The CRC error count is zero
C.Data frames are 1500 bytes, which is too small for FCoE
D.The admin port mode is F instead of NP
Why A: PFC frames received (152) with zero sent suggests the interface is receiving pause frames from the peer, possibly due to congestion or a PFC configuration mismatch. Option B is correct. Option A (CRC errors) none. Option C (mode) is fine. Option D (MTU) default 1500 for data frames is consistent.
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Question Discussion
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