The answer is that the upstream MDS is not configured to accept NPV connections. This is the most likely cause because FCoE NPV relies on NPIV (N_Port ID Virtualization) on the upstream switch to register and forward FLOGI requests from the downstream Nexus; without NPIV enabled on the MDS uplink interfaces, the MDS will reject all login attempts, leaving the Nexus FLOGI table empty even though the physical uplinks are up. On the Cisco DCCOR 350-601 exam, this scenario tests your understanding of the NPV architecture and the mandatory NPIV requirement on the core switch—a common trap is to assume the issue lies with VLAN or VSAN mapping when the real problem is the upstream’s failure to accept NPV connections. Remember the memory tip: “No NPIV, no NPV login”—if the upstream doesn’t have NPIV, the downstream NPV switch cannot forward any FLOGIs.
350-601 Storage Network Practice Question
This 350-601 practice question tests your understanding of storage network. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.
A large data center uses a Cisco Nexus 9000 switch with FCoE NPV feature. The switch is connected to an MDS 9700 upstream. The network team recently replaced the MDS 9700 with a new one. After the replacement, the FCoE hosts are unable to log in to the storage fabric. The Nexus switch shows that the FCoE NPV uplinks are up but no FLOGIs are being forwarded. The show npv flogi-table on the Nexus is empty. The upstream MDS shows that the uplinks are in VSAN 100, and the zoning is correct. The Nexus switch configuration includes 'feature npv' and 'npv enable' on the relevant interfaces. The FCoE VLAN 100 is mapped to VSAN 100. 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 upstream MDS is not configured to accept NPV connections
The most likely cause is that the upstream MDS is not configured to accept NPV connections. For NPV to work, the upstream switch (MDS) must have NPIV enabled on the uplink interfaces. Without NPIV, the MDS will reject FLOGI requests from the Nexus. Other options: FKA-adv-period affects keep-alives, not login; FIP snooping is on the Nexus but would not cause empty flogi-table if uplinks are up; VLAN mapping is correct.
Key principle: A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
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 upstream MDS is not configured to accept NPV connections
Why this is correct
The MDS needs NPIV enabled on the uplink interfaces to proxy FLOGIs from the Nexus.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Access ports place end devices into a single VLAN.
✗
The FIP snooping policy is blocking the FLOGI traffic
Why it's wrong here
FIP snooping filters on the Nexus, but if policy were blocking, the uplinks might show errors, not just empty flogi-table.
✗
The Nexus switch is missing the 'fcoe fka-adv-period' configuration
Why it's wrong here
This parameter affects keep-alive intervals, not initial login.
✗
The FCoE hosts are not in the same VLAN as the FCoE NPV uplinks
Common exam trap: an active trunk can still block the VLAN you need
A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.
Trap categories for this question
Command / output trap
FIP snooping filters on the Nexus, but if policy were blocking, the uplinks might show errors, not just empty flogi-table.
Detailed technical explanation
How to think about this question
VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.
KKey Concepts to Remember
Access ports place end devices into a single VLAN.
Trunk ports carry multiple VLANs between switches.
Allowed VLAN lists decide which VLANs can cross a trunk.
Native VLAN mismatch can create confusing symptoms.
TExam Day Tips
→Use show vlan brief to verify access VLANs.
→Use show interfaces trunk to verify trunk state and allowed VLANs.
→Do not treat every same-VLAN issue as a routing problem.
Key takeaway
A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
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.
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 350-601 questions on switching, trunking, and access-port configuration.
Storage Network — This question tests Storage Network — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: The upstream MDS is not configured to accept NPV connections — The most likely cause is that the upstream MDS is not configured to accept NPV connections. For NPV to work, the upstream switch (MDS) must have NPIV enabled on the uplink interfaces. Without NPIV, the MDS will reject FLOGI requests from the Nexus. Other options: FKA-adv-period affects keep-alives, not login; FIP snooping is on the Nexus but would not cause empty flogi-table if uplinks are up; VLAN mapping is correct.
What should I do if I get this 350-601 question wrong?
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 350-601 questions on switching, trunking, and access-port configuration.
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?
Access ports place end devices into a single VLAN.
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