Quick Answer
The answer is that LUN masking is not configured on the storage array. Even when zoning correctly pairs a host WWPN with a target WWPN, zoning only controls which devices can communicate across the fabric; it does not control which LUNs the storage array presents to a specific initiator. Without LUN masking, the array has no mapping that tells it to expose a particular LUN to that host’s WWPN, so the LUN remains invisible despite the zone being active. On the Cisco DCCOR 350-601 exam, this scenario tests your ability to distinguish between fabric-level access control (zoning) and array-level access control (LUN masking). A common trap is assuming that correct zoning alone guarantees LUN visibility—it does not. Remember the mnemonic: “Zone the path, mask the LUN.”
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 storage administrator notices that a host is unable to see a LUN after zoning is configured. The zone contains the host WWPN and the target WWPN. The LUN is not masked at the storage array. 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.
LUN masking is not configured on the storage array.
LUN masking is required to present LUNs to specific hosts.
The host requires NPIV to be enabled.
Why wrong: NPIV is for multiple N-port IDs, not necessary here.
The host is in a different VSAN.
Why wrong: No evidence of VSAN mismatch.
The zone is incorrectly configured.
Why wrong: Zone has correct WWPNs.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
LUN masking is not configured on the storage array.
The host cannot see the LUN because LUN masking is not configured on the storage array. Even with correct zoning (host WWPN to target WWPN), the storage array must explicitly grant access to specific LUNs for a given initiator WWPN. Without LUN masking, the target will not present the LUN to the host, regardless of zone membership.
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.
LUN masking is not configured on the storage array.
Why this is correct
LUN masking is required to present LUNs to specific hosts.
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.
The host requires NPIV to be enabled.
Why it's wrong here
NPIV is for multiple N-port IDs, not necessary here.
The host is in a different VSAN.
Why it's wrong here
No evidence of VSAN mismatch.
The zone is incorrectly configured.
Why it's wrong here
Zone has correct WWPNs.
Common exam traps
Cisco often tests the distinction between fabric-level zoning (which controls which ports can communicate) and storage-array-level LUN masking (which controls which LUNs are visible to an initiator), leading candidates to incorrectly assume zoning alone grants LUN access.
Detailed technical explanation
LUN masking is a storage-array-level access control that maps specific LUNs to specific initiator WWPNs, often implemented via a LUN-to-initiator group binding. In Cisco MDS switches, zoning operates at the FC fabric layer (using WWPNs or FC IDs), while LUN masking is handled by the storage array's OS (e.g., Cisco MDS's device-alias or storage-side configuration). A common real-world scenario is when a zone is correctly built but the storage array's LUN masking database (e.g., in a Cisco UCS or NetApp array) is empty for that initiator, causing the LUN to remain hidden.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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Storage Network — study guide chapter
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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: LUN masking is not configured on the storage array. — The host cannot see the LUN because LUN masking is not configured on the storage array. Even with correct zoning (host WWPN to target WWPN), the storage array must explicitly grant access to specific LUNs for a given initiator WWPN. Without LUN masking, the target will not present the LUN to the host, regardless of zone membership.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Read the scenario before looking for a memorised answer.
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Same concept, more angles
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Variation 1. A new storage administrator is configuring LUN masking on a Cisco MDS switch. The storage array presents two LUNs to the fabric with the same LUN ID (0) but to different target ports. The administrator wants to ensure that a specific host can access both LUNs. The host is connected to a single HBA port. The host will see both target ports in the same zone. After zoning, the host discovers both target ports but only sees the first LUN. The show flogi database shows the host's pWWN with two FC IDs assigned. What is the most likely issue?
easyWhy D: The host discovers both target ports via FLOGI but only sees the first LUN because the storage array has not been configured to mask the LUNs to the host's pWWN. LUN masking is an array-side access control that determines which initiator WWNs can see which LUNs; without it, the array defaults to presenting only the first LUN (LUN 0) to any initiator. The zone is correctly configured (both target ports are in the same zone and the host sees them), and the LUN ID conflict is irrelevant because the LUNs are on different target ports, so they can share the same LUN ID without conflict.
Last reviewed: Jun 24, 2026
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