Quick Answer
The answer is the `vlan 100` command entered in global configuration mode. This is correct because on a Cisco IOS switch, VLANs are created as logical Layer 2 networks within the VLAN database, and the `vlan` command followed by the VLAN ID both creates the VLAN and places you into VLAN configuration mode, where you can assign a name or other parameters. On the ENCOR 350-401 exam, this question tests your fundamental understanding of VLAN lifecycle management versus interface-level commands like `switchport access vlan 100`, which only assigns an existing VLAN to a port, or `interface vlan 100`, which creates a Layer 3 SVI. A common trap is confusing the creation of the VLAN itself with the creation of its routed interface. Remember the memory tip: to bring a VLAN to life, you must first "call it by name" with `vlan [ID]` in global config—everything else is just assigning or routing it.
This 350-401 practice question tests your understanding of infrastructure. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
An engineer is configuring a new VLAN 100 on a switch. Which command must be used to create the VLAN?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "which command"
Why it matters: Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
vlan 100
This creates VLAN 100.
switchport access vlan 100
Why wrong: This assigns an interface to VLAN 100.
vlan database
Why wrong: This is a legacy command.
interface vlan 100
Why wrong: This creates an SVI.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
vlan 100
The correct command to create a new VLAN on a Cisco IOS switch is 'vlan 100' entered in global configuration mode. This command creates VLAN 100 and enters VLAN configuration mode, allowing you to assign a name or other parameters. The other options either apply an existing VLAN to an interface, use a deprecated method, or create a switched virtual interface (SVI) for Layer 3 routing, none of which actually create the VLAN itself.
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.
vlan 100
Why this is correct
This creates VLAN 100.
Clue confirmation
The clue word "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
switchport access vlan 100
Why it's wrong here
This assigns an interface to VLAN 100.
vlan database
Why it's wrong here
This is a legacy command.
interface vlan 100
Why it's wrong here
This creates an SVI.
Common exam traps
Cisco often tests the distinction between creating a VLAN and applying it to an interface, so candidates mistakenly choose 'switchport access vlan 100' thinking it both creates and assigns the VLAN, when in fact it only assigns an existing VLAN.
Trap categories for this question
Command / output trap
This is a legacy command.
Detailed technical explanation
Under the hood, VLAN creation in IOS writes to the VLAN database file (vlan.dat) and the running configuration, with the VLAN being stored in the VLAN Trunking Protocol (VTP) domain if VTP is enabled. A subtle behavior is that if VTP is in transparent mode, VLANs are created locally and stored in the running config, but in server/client mode, the VLAN must be consistent across the domain. In real-world scenarios, failing to create the VLAN before assigning it to an interface can lead to ports being in an err-disabled state or the VLAN being pruned on trunk links.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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FAQ
Infrastructure — This question tests Infrastructure — Read the scenario before looking for a memorised answer..
The correct answer is: vlan 100 — The correct command to create a new VLAN on a Cisco IOS switch is 'vlan 100' entered in global configuration mode. This command creates VLAN 100 and enters VLAN configuration mode, allowing you to assign a name or other parameters. The other options either apply an existing VLAN to an interface, use a deprecated method, or create a switched virtual interface (SVI) for Layer 3 routing, none of which actually create the VLAN itself.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "which command". Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
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