The answer is that the NPIV limit or the number of allowed logins has been exceeded on the upstream switch. This is correct because NPIV resource exhaustion occurs when multiple virtual WWPNs share a single physical FC port, and each virtual machine’s fabric login (FLOGI) consumes a finite login resource on the MDS switch; once the per-interface or per-VSAN limit is reached, the switch logs "FLOGI rejected: no available resources" and denies new logins. On the Cisco DCCOR 350-601 exam, this scenario tests your understanding of NPIV scalability limits versus physical port exhaustion—a common trap is confusing this with a lack of Fibre Channel bandwidth or zoning misconfiguration. Remember the key distinction: NPIV is about virtual WWPN density, not physical port count. Memory tip: "NPIV = N_Port ID Virtualization; think 'Virtual IDs, Real Limits'—each virtual login burns a resource slot, so count your VMs against the switch’s login budget."
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.
A company is deploying a multi-tenant environment with several virtualized hosts using NPIV. Each virtual machine requires its own WWPN. During testing, some VMs cannot log into the SAN. The MDS switch logs show 'FLOGI rejected: no available resources'. 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 NPIV limit or the number of allowed logins has been exceeded on the upstream switch
The error 'FLOGI rejected: no available resources' on an MDS switch in an NPIV environment indicates that the switch has exhausted its allocated resources for handling fabric logins (FLOGIs) from N_Port ID Virtualization (NPIV) initiators. NPIV allows multiple virtual WWPNs to share a single physical FC port, but each virtual login consumes a login resource on the upstream switch. When the NPIV limit or the maximum number of allowed logins per interface or per VSAN is exceeded, the switch rejects new FLOGIs, preventing VMs from logging into the SAN.
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 maximum FC frame size is set incorrectly on the switch
Why it's wrong here
Frame size affects throughput, not login resources.
✗
The VSAN maximum number of devices has been reached
Why it's wrong here
VSAN device limits are large and rarely hit.
✗
The zone set is full and cannot accept more members
Why it's wrong here
Zone set size limit is not reached in most cases.
✓
The NPIV limit or the number of allowed logins has been exceeded on the upstream switch
Why this is correct
By default, NPIV max logins may be hit with many VMs.
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 resource exhaustion (NPIV login limits) and configuration errors (zoning or VSAN device limits) by using the specific error message 'FLOGI rejected: no available resources', which candidates mistakenly attribute to zoning or VSAN device limits instead of NPIV login resource depletion.
Detailed technical explanation
How to think about this question
Under the hood, each NPIV login consumes a Virtual N_Port (VN_Port) context and a Fibre Channel login (FLOGI) resource on the upstream switch, which is tracked per physical interface or per VSAN. The 'show npiv status' and 'show flogi database' commands on the MDS switch reveal the current login count and the configured limits (e.g., 'npiv max-logins 256'). In real-world scenarios, oversubscribing virtual machines per physical HBA without adjusting the NPIV login limit is a common misconfiguration, leading to intermittent SAN connectivity failures that are hard to diagnose without checking resource counters.
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 NPIV limit or the number of allowed logins has been exceeded on the upstream switch — The error 'FLOGI rejected: no available resources' on an MDS switch in an NPIV environment indicates that the switch has exhausted its allocated resources for handling fabric logins (FLOGIs) from N_Port ID Virtualization (NPIV) initiators. NPIV allows multiple virtual WWPNs to share a single physical FC port, but each virtual login consumes a login resource on the upstream switch. When the NPIV limit or the maximum number of allowed logins per interface or per VSAN is exceeded, the switch rejects new FLOGIs, preventing VMs from logging into the SAN.
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.
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