The correct answer is that buffer credits manage congestion and ensure lossless delivery over distance in Fibre Channel. This is accurate because buffer credits function as a flow control mechanism that tracks the number of frames a sender can transmit before receiving an acknowledgment from the receiver, preventing buffer overflow and frame loss. In a Fibre Channel SAN, each credit represents a buffer available at the receiving end, so the sender must wait for credits to be returned before sending more frames—this directly controls congestion and guarantees lossless delivery even across long distances. On the Cisco DCCOR / CCNP Data Center Core 350-601 exam, this concept tests your understanding of how Fibre Channel maintains data integrity in storage networks; a common trap is confusing buffer credits with Ethernet pause frames or assuming they only apply to short distances. Remember the mnemonic: Credits Control Congestion, ensuring Lossless Links.
350-601 Storage Network Practice Question
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.
In a Fibre Channel SAN, flow control is managed by buffer credits. Which statement about buffer credits is accurate?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Buffer credits help manage congestion and ensure lossless delivery over distance
Buffer credits are a flow control mechanism in Fibre Channel that manage congestion by tracking the number of frames a sender can transmit before receiving an acknowledgment. They ensure lossless delivery over distance by preventing buffer overflow at the receiver, which is critical for maintaining data integrity in SANs. Option D correctly states this dual role of congestion management and lossless delivery.
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.
✗
Buffer credits are allocated per VSAN to isolate traffic
Oversizing can waste resources; benefit is mostly for long-distance links.
✗
Buffer credits are used in FCoE to ensure lossless delivery
Why it's wrong here
FCoE uses PFC, not buffer credits.
✓
Buffer credits help manage congestion and ensure lossless delivery over distance
Why this is correct
BB_credits allow a sender to send multiple frames without waiting for acknowledgment.
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 Fibre Channel buffer credits and FCoE's Priority Flow Control (PFC), so the trap here is confusing the two lossless mechanisms and assuming buffer credits apply to FCoE.
Detailed technical explanation
How to think about this question
Buffer credits represent the number of receive buffers available at the remote port; each credit allows one frame to be sent. The BB_Credit value is negotiated during Fabric Login (FLOGI) and can be adjusted using the 'switchport fcrxbbcredit' command on Cisco MDS switches. In long-haul links, insufficient buffer credits can cause underutilization because the sender must wait for credits before transmitting, leading to reduced throughput.
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: Buffer credits help manage congestion and ensure lossless delivery over distance — Buffer credits are a flow control mechanism in Fibre Channel that manage congestion by tracking the number of frames a sender can transmit before receiving an acknowledgment. They ensure lossless delivery over distance by preventing buffer overflow at the receiver, which is critical for maintaining data integrity in SANs. Option D correctly states this dual role of congestion management and lossless delivery.
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.
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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