The best practice for FEX host interfaces is to enable Virtual Port Channel (vPC) on the parent switch. This configuration allows the Fabric Extender to be dual-homed to two separate parent switches, providing link-level redundancy and active-active forwarding rather than relying on a single point of failure. Without vPC, a parent switch failure would cause traffic black-holing, as the FEX cannot independently failover. On the Cisco DCCOR 350-601 exam, this concept tests your understanding of high-availability design in the data center, often appearing in scenario-based questions where you must choose between STP, vPC, or standalone links. A common trap is assuming that simply connecting a FEX to two switches provides redundancy—it does not without vPC, because the FEX treats one link as a blocking port. Remember the memory tip: “FEX dual-homing without vPC is just two single points of failure.”
350-601 Network Practice Question
This 350-601 practice question tests your understanding of network. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 network engineer is configuring a Fabric Extender (FEX) to connect to a parent switch. Which best practice should be followed for FEX host interfaces?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable Virtual Port Channel (vPC) on the parent switch.
Enabling Virtual Port Channel (vPC) on the parent switch is a best practice for FEX host interfaces because it allows the FEX to be dual-homed to two separate parent switches, providing link-level redundancy and active-active forwarding. Without vPC, the FEX would rely on a single parent switch, creating a single point of failure and potentially causing traffic black-holing during a parent switch failure.
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.
✗
Configure all host interfaces as trunk ports.
Why it's wrong here
Host interfaces may be access ports; not a best practice.
Enable Virtual Port Channel (vPC) on the parent switch.
Why this is correct
vPC provides active-active redundancy for FEX uplinks.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Disable spanning-tree on FEX host interfaces.
Why it's wrong here
Spanning-tree should remain enabled to prevent loops.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that FEX uplinks require LACP or that FEX IDs can be shared for redundancy, when in fact FEX uplinks use static fabric channels and each FEX must have a unique ID.
Detailed technical explanation
How to think about this question
Under the hood, a FEX operates as a remote linecard of the parent switch, and its host interfaces are managed by the parent's control plane. When vPC is enabled on the parent switches, the FEX can be dual-homed using two separate fabric uplinks to each parent, and the vPC domain ensures that both parents present a consistent L2 forwarding state, allowing the FEX to use both uplinks simultaneously without STP blocking one. In a real-world scenario, this is critical for data center topologies where server connectivity must survive a parent switch failure without relying on STP convergence, which can take several seconds.
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.
Network — This question tests Network — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enable Virtual Port Channel (vPC) on the parent switch. — Enabling Virtual Port Channel (vPC) on the parent switch is a best practice for FEX host interfaces because it allows the FEX to be dual-homed to two separate parent switches, providing link-level redundancy and active-active forwarding. Without vPC, the FEX would rely on a single parent switch, creating a single point of failure and potentially causing traffic black-holing during a parent switch failure.
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: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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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