The answer is that the storage target has not logged into the fabric. This is the most likely cause because the FLOGI database and the FCNS database serve distinct purposes in a Fibre Channel SAN: the FLOGI database records all devices that have completed the Fabric Login (FLOGI) process, which the host has done, while the FCNS database only lists devices that have additionally registered their FC-4 type and SCSI features with the Fabric Name Server via FDISC or PLOGI. Since the storage target is absent from the FCNS database, it has not completed this registration, meaning it is not logged into the fabric and cannot be discovered by the host. On the Cisco DCCOR 350-601 exam, this scenario tests your understanding of the FLOGI vs FCNS database difference, often appearing as a troubleshooting trap where candidates confuse a successful FLOGI with full fabric integration. Remember the memory tip: FLOGI is the handshake, FCNS is the phonebook—if a device isn’t in the phonebook, it can’t be called.
350-601 Storage Network Practice Question
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 Cisco MDS switch is connected to a Fibre Channel storage array and a host. The host cannot see the storage LUNs. The 'show flogi database' command on the MDS shows the host's WWPN, but the 'show fcns database' does not show the storage target. 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.
Why wrong: Incorrect zoning would prevent communication, but the target would still appear in the name server if logged in.
B
The host and target are in different VSANs.
Why wrong: If they are in different VSANs, the host would not see the target, but the host is in the fabric, so the target is either not logged in or in a different VSAN.
C
The storage target is not logged into the fabric.
The 'show fcns database' shows only devices that have logged into the fabric; if the target is not logged in, it won't appear.
D
The host is not in the name server database.
Why wrong: The host appears in 'show flogi database', so it is logged in and should be in the name server.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The storage target is not logged into the fabric.
The 'show flogi database' command displays all devices that have completed the Fabric Login (FLOGI) process, which the host has done. However, the 'show fcns database' command lists only devices that have registered with the Fabric Name Server (via FDISC or FLOGI with PLOGI). Since the storage target is not in the name server database, it means the target has not logged into the fabric (or has not registered its FC-4 type/SCSI features), preventing the host from discovering its LUNs. This is the most likely cause because the host can see its own WWPN in the FLOGI database but cannot see the target in the FCNS database.
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.
✗
The zone configuration is incorrect.
Why it's wrong here
Incorrect zoning would prevent communication, but the target would still appear in the name server if logged in.
✗
The host and target are in different VSANs.
Why it's wrong here
If they are in different VSANs, the host would not see the target, but the host is in the fabric, so the target is either not logged in or in a different VSAN.
✓
The storage target is not logged into the fabric.
Why this is correct
The 'show fcns database' shows only devices that have logged into the fabric; if the target is not logged in, it won't appear.
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 is not in the name server database.
Why it's wrong here
The host appears in 'show flogi database', so it is logged in and should be in the name server.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between FLOGI (physical login) and FCNS registration (name server entry), leading candidates to incorrectly assume that a device visible in 'show flogi database' must also be in the fabric name server database.
Trap categories for this question
Command / output trap
The host appears in 'show flogi database', so it is logged in and should be in the name server.
Detailed technical explanation
How to think about this question
The FLOGI process assigns a Fibre Channel address (FC-ID) and establishes a session with the switch, while the Fabric Name Server registration (via FDISC or implicit FLOGI) populates the FCNS database with the device's WWPN, FC-4 types, and symbolic names. A storage target may fail to log in due to misconfigured port settings (e.g., disabled, incorrect speed/duplex, or incompatible buffer-to-buffer credits) or a faulty SFP, causing it to never complete FLOGI and thus never appear in the FCNS database. In real-world scenarios, this often occurs after a firmware upgrade or cable reseating where the target does not re-initiate login.
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: The storage target is not logged into the fabric. — The 'show flogi database' command displays all devices that have completed the Fabric Login (FLOGI) process, which the host has done. However, the 'show fcns database' command lists only devices that have registered with the Fabric Name Server (via FDISC or FLOGI with PLOGI). Since the storage target is not in the name server database, it means the target has not logged into the fabric (or has not registered its FC-4 type/SCSI features), preventing the host from discovering its LUNs. This is the most likely cause because the host can see its own WWPN in the FLOGI database but cannot see the target in the FCNS database.
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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