The correct action is to verify the active zone set on the MDS switches and re-activate it if necessary. This resolves the vHBA link down post-firmware upgrade on MDS because the firmware upgrade can deactivate or fail to save the active zone set, which disrupts the Fibre Channel fabric’s ability to deliver a FLOGI response to the initiators. Since the storage LUNs remain accessible from the MDS, the issue is not with the storage array but with the zoning configuration, and re-activating the zone set re-establishes the FC zones, allowing the vHBAs to complete fabric login and resume boot from SAN. On the Cisco DCCOR 350-601 exam, this scenario tests your understanding of FC zoning persistence and the impact of firmware upgrades on fabric services—a common trap is to focus on the UCS side or blame the VIC adapter. Remember: after any MDS firmware upgrade, always check the active zone set first; think “FLOGI fails, zone set stale.”
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 medium-sized enterprise has a Cisco UCS environment with two Fabric Interconnects (FIs) in a cluster. There are 10 blade servers, each with a VIC 1340 adapter. The SAN consists of two MDS 9148S switches in a VSAN for storage. Each server is configured with two vHBAs (primary and secondary) connecting to the SAN via the FIs. Recently, after a firmware upgrade on the MDS switches, several servers are unable to boot from SAN. The storage administrator confirms that the storage array LUNs are accessible from the MDS switches. The UCS administrator reports that the vHBAs show a 'link down' status on the FI. Which action should be taken to resolve the issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "primary"
Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Verify the active zone set on the MDS switches and re-activate it if necessary.
The 'link down' status on the vHBAs indicates that the Fibre Channel fabric is not properly delivering the FLOGI (Fabric Login) response to the initiators. Since the storage LUNs are accessible from the MDS switches, the issue is likely that the active zone set was deactivated or not saved after the firmware upgrade, preventing the vHBAs from logging into the fabric. Re-activating the zone set on the MDS switches will re-establish the FC zones and allow the vHBAs to complete FLOGI and resume boot from 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.
✗
Reconfigure the vHBAs on the UCS Manager with new WWPNs.
Why it's wrong here
WWPNs are persistent; reconfiguration is unnecessary.
✗
Check the storage array LUN masking and re-apply LUN access.
Why it's wrong here
LUNs are accessible from MDS, so storage is fine.
✓
Verify the active zone set on the MDS switches and re-activate it if necessary.
Why this is correct
Firmware upgrade may deactivate the zone set.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Downgrade the MDS firmware to the previous version.
Why it's wrong here
Not necessary; configuration issue is more likely.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between storage array LUN masking (target-side) and FC fabric zoning (switch-side); the trap here is that candidates assume a 'link down' on the vHBA must be a physical or HBA configuration issue, when in fact it is a fabric-level problem caused by missing or inactive zone sets after a switch upgrade.
Detailed technical explanation
How to think about this question
During an MDS firmware upgrade, the running configuration (including the active zone set) may be lost if not saved to the startup configuration before the upgrade. The 'show zoneset active' command on the MDS can verify if the zone set is present; if not, the 'zoneset activate name <name> vsan <vsan-id>' command is needed. The vHBA 'link down' status in UCS Manager is a direct symptom of the FC initiator failing FLOGI because the switch does not have an active zone set to accept the login.
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 network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
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: Verify the active zone set on the MDS switches and re-activate it if necessary. — The 'link down' status on the vHBAs indicates that the Fibre Channel fabric is not properly delivering the FLOGI (Fabric Login) response to the initiators. Since the storage LUNs are accessible from the MDS switches, the issue is likely that the active zone set was deactivated or not saved after the firmware upgrade, preventing the vHBAs from logging into the fabric. Re-activating the zone set on the MDS switches will re-establish the FC zones and allow the vHBAs to complete FLOGI and resume boot from 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: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
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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