The answer is that the server's service profile does not include a secondary vNIC for Fabric B. This is the most likely cause because UCS vNIC failover requires a secondary vNIC explicitly defined in the service profile to enable the primary vNIC to shift traffic to the other fabric’s uplink. The 'Failover: Enabled' setting on the vNIC template alone only permits failover behavior; without a secondary vNIC assigned in the profile, the vNIC remains pinned to its original fabric and cannot fail over when Fabric Interconnect A fails. On the Cisco DCCOR 350-601 exam, this concept tests your understanding that failover is a two-part configuration—template settings and profile assignment—and a common trap is assuming the template checkbox alone guarantees redundancy. Remember the memory tip: "No secondary, no failover—the profile must pair both fabrics."
350-601 Compute Practice Question
This 350-601 practice question tests your understanding of compute. 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.
Exhibit
Fabric Interconnect A - Ethernet Uplink Configuration
interface Ethernet1/1
switchport mode trunk
switchport trunk allowed vlan 10,20,30
spanning-tree port type edge trunk
no shutdown
Fabric Interconnect B - Ethernet Uplink Configuration
interface Ethernet1/1
switchport mode trunk
switchport trunk allowed vlan 10,20,30
spanning-tree port type edge trunk
no shutdown
UCS Manager vNIC Template Config
vNIC Name: vNIC-A
Fabric ID: A
VLANs: 10 (Native), 20, 30
Failover: Enabled
vNIC Name: vNIC-B
Fabric ID: B
VLANs: 10 (Native), 20, 30
Failover: Enabled
Refer to the exhibit. A UCS administrator has configured vNIC templates as shown. Both Fabric Interconnects have identical uplink configurations. The vNIC templates have 'Failover: Enabled'. However, when Fabric Interconnect A fails, servers using vNIC-A do not fail over to Fabric Interconnect B. 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 server's service profile does not include a secondary vNIC for Fabric B.
Option D is correct because the server's service profile must include both a primary vNIC (for Fabric Interconnect A) and a secondary vNIC (for Fabric Interconnect B) to enable failover. The 'Failover: Enabled' setting on the vNIC template only allows the vNIC to use the other fabric's uplink if a secondary vNIC is explicitly defined in the service profile; without it, the vNIC is pinned to its original fabric and cannot fail over.
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.
✗
A pin group is configured that forces traffic to Fabric Interconnect A.
Why it's wrong here
No pin group is mentioned in the exhibit.
✗
The native VLAN (10) is not allowed on Fabric Interconnect B's trunk.
The uplink interfaces are configured with 'spanning-tree port type edge trunk', which blocks failover traffic.
Why it's wrong here
'spanning-tree port type edge trunk' is a standard setting and does not block failover.
✓
The server's service profile does not include a secondary vNIC for Fabric B.
Why this is correct
Failover requires a secondary vNIC on the other fabric in the same service profile.
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 misconception that enabling 'Failover' on a vNIC template alone is sufficient for failover, when in reality a secondary vNIC must be explicitly added to the service profile to provide the alternate fabric path.
Detailed technical explanation
How to think about this question
In Cisco UCS, vNIC failover requires a secondary vNIC in the service profile that is pinned to the other fabric; the 'Failover: Enabled' template setting merely permits the vNIC to use the secondary vNIC's path when the primary fabric fails. Without a secondary vNIC, the vNIC remains pinned to its original fabric and cannot switch, even if the uplink configuration is identical on both Fabric Interconnects. This design ensures deterministic traffic flow and avoids loops, as the server's MAC address is only active on one fabric at a time.
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.
Compute — This question tests Compute — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The server's service profile does not include a secondary vNIC for Fabric B. — Option D is correct because the server's service profile must include both a primary vNIC (for Fabric Interconnect A) and a secondary vNIC (for Fabric Interconnect B) to enable failover. The 'Failover: Enabled' setting on the vNIC template only allows the vNIC to use the other fabric's uplink if a secondary vNIC is explicitly defined in the service profile; without it, the vNIC is pinned to its original fabric and cannot fail over.
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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