Quick Answer
The correct answer is that Lossless Ethernet, enabled by Priority Flow Control (PFC), is a required characteristic of an FCoE SAN. This is because Fibre Channel over Ethernet relies on a lossless fabric to prevent frame drops, which would otherwise corrupt Fibre Channel frames and break the protocol’s inherent reliability. PFC, defined in IEEE 802.1Qbb, achieves this by pausing traffic on individual CoS queues, ensuring no-drop behavior specifically for FCoE traffic while allowing best-effort delivery for other data. On the Cisco DCCOR 350-601 exam, this concept tests your understanding of FCoE SAN fundamentals and often appears as a trap where candidates mistakenly choose standard Ethernet features like jumbo frames or VLANs. A common memory tip is to remember that FCoE cannot tolerate any loss, so think “PFC = Pause for FCoE” to link the requirement directly to Priority Flow Control.
This 350-601 practice question tests your understanding of storage network. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Which of the following is a required characteristic of an FCoE SAN?
Jumbo frames must be enabled.
Why wrong: Not strictly required, though recommended.
Spanning Tree Protocol must be disabled.
Why wrong: STP can be used but is often disabled for FCoE VLANs.
Link aggregation (LACP) is required.
Why wrong: Not required.
Lossless Ethernet (PFC) must be enabled.
FCoE requires no-drop.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Lossless Ethernet (PFC) must be enabled.
FCoE (Fibre Channel over Ethernet) requires a lossless Ethernet fabric to prevent frame drops, which would corrupt Fibre Channel frames. Priority Flow Control (PFC), defined in IEEE 802.1Qbb, enables lossless operation by pausing traffic on individual CoS queues, ensuring no-drop behavior for FCoE traffic. Without PFC, standard Ethernet's best-effort delivery would cause frame loss, breaking FCoE's reliability requirements.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Jumbo frames must be enabled.
Why it's wrong here
Not strictly required, though recommended.
Spanning Tree Protocol must be disabled.
Why it's wrong here
STP can be used but is often disabled for FCoE VLANs.
Link aggregation (LACP) is required.
Why it's wrong here
Not required.
Lossless Ethernet (PFC) must be enabled.
Why this is correct
FCoE requires no-drop.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Cisco often tests the misconception that jumbo frames are mandatory for FCoE, but the actual required characteristic is lossless Ethernet via PFC, as jumbo frames are optional and only improve efficiency.
Detailed technical explanation
PFC works by using pause frames on a per-priority basis (8 CoS values), allowing FCoE traffic (typically CoS 3) to be paused independently from other traffic, preventing buffer overflow without halting all traffic. In a converged network, FCoE relies on PFC in conjunction with Enhanced Transmission Selection (ETS, IEEE 802.1Qaz) to allocate bandwidth and ensure lossless delivery, which is critical for Fibre Channel's credit-based flow control to function over Ethernet. A real-world scenario is a Cisco UCS fabric interconnect where FCoE VLANs require PFC enabled on the uplink interfaces to maintain SAN stability.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
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FAQ
Storage Network — This question tests Storage Network — Read the scenario before looking for a memorised answer..
The correct answer is: Lossless Ethernet (PFC) must be enabled. — FCoE (Fibre Channel over Ethernet) requires a lossless Ethernet fabric to prevent frame drops, which would corrupt Fibre Channel frames. Priority Flow Control (PFC), defined in IEEE 802.1Qbb, enables lossless operation by pausing traffic on individual CoS queues, ensuring no-drop behavior for FCoE traffic. Without PFC, standard Ethernet's best-effort delivery would cause frame loss, breaking FCoE's reliability requirements.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This 350-601 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-601 exam.
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