Network+ VLAN trunks: tags, native VLANs and allowed lists
An access port normally connects an endpoint to one VLAN. An 802.1Q trunk carries multiple VLANs between compatible devices. Verify the allowed VLAN list at both ends and understand how untagged traffic is assigned. Native VLAN mismatches can place untagged frames into different segments. Routing is still needed for IP communication between distinct VLAN subnets.
How to read the scenario
If one VLAN fails while others cross the same link, compare VLAN membership and trunk permission before replacing the entire cable path.
Identify the required outcome, the evidence already provided, and the limits on the technician’s action. Compare every option against those details before deciding. Record why the closest alternative does not meet the stated need.
Original practice example
A network team adds a redundant Layer 2 link between switches. Which TWO measures are appropriate before enabling it? Select TWO.
- Confirm consistent intended VLAN transport.
- Disable spanning tree on every switch.
- Verify loop-prevention behavior.
- Assume any extra cable automatically doubles every flow speed.
Show the answer and explanation
Confirm consistent intended VLAN transport.; Verify loop-prevention behavior.
Loop prevention and correct VLAN transport are essential. Redundant links can create loops, and aggregate links do not necessarily double a single flow throughput.
Study questions
Which objective does this guide support?
N10-009, objective 2.2. This independent guide supports original practice and does not replace the full official objectives.
What should I watch for in a scenario?
If one VLAN fails while others cross the same link, compare VLAN membership and trunk permission before replacing the entire cable path.
Source and version
CompTIA official N10-009 objectives, objective 2.2. Verified November 5, 2026. Use the exam code when choosing study materials; similarly named certifications can have different objectives.