Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A switchport connected to another switch should carry VLANs 10, 20, and 30. The interface is operational, but only VLAN 10 works. VLANs 20 and 30 fail. Which explanation is most likely if the port was accidentally configured as an access port in VLAN 10?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
The interface is carrying only VLAN 10 because an access port does not transport multiple VLANs like a trunk.
This is correct because an access-port misconfiguration explains why only the configured VLAN works.
B
Distractor review
VLAN 20 and 30 require different IP subnet masks on the switches.
This is wrong because the immediate problem is the Layer 2 switchport role, not IP mask design.
C
Distractor review
Every inter-switch link must use a routed port instead of a trunk.
This is wrong because trunks are the normal mechanism for carrying multiple VLANs between switches.
D
Distractor review
STP blocks all VLANs except VLAN 10 by design.
This is wrong because STP does not inherently permit only one VLAN simply because it is VLAN 10.
Common exam trap
Common exam trap: answer the scenario, not the keyword
The exam trap lies in confusing access ports with trunk ports on inter-switch links. Candidates may see the interface is operational and assume all VLANs should work, overlooking that an access port only carries one VLAN untagged. This mistake leads to VLAN 20 and 30 traffic failing silently because the switch drops frames tagged for VLANs other than the access VLAN. The trap exploits the assumption that physical connectivity implies correct logical VLAN forwarding, which is false when port modes are misconfigured.
Technical deep dive
How to think about this question
VLANs (Virtual Local Area Networks) segment a physical switch into multiple logical networks, allowing traffic separation at Layer 2. Switchports can be configured as access ports or trunk ports. An access port carries traffic for a single VLAN, tagging none or one VLAN ID, typically used for end devices. A trunk port, however, carries traffic for multiple VLANs simultaneously by tagging frames with VLAN IDs using protocols like IEEE 802.1Q, enabling inter-switch VLAN communication. When connecting two switches that must share multiple VLANs, the interface must be configured as a trunk port. This configuration allows VLANs 10, 20, and 30 to traverse the link. If the port is mistakenly set as an access port assigned to VLAN 10, it will only forward untagged frames for VLAN 10 and drop or ignore traffic from VLANs 20 and 30. This misconfiguration causes VLAN 20 and 30 traffic to fail despite the physical link being operational. This scenario is a common exam trap where candidates confuse access and trunk port roles. Practically, an access port restricts traffic to a single VLAN, so multi-VLAN communication between switches requires trunking. The exam tests understanding of VLAN tagging and port modes, emphasizing that an access port cannot carry multiple VLANs, which is essential for inter-switch links in VLAN-segmented networks.
KKey Concepts to Remember
- A switchport configured as an access port carries traffic for only one VLAN and does not tag frames with VLAN IDs.
- A trunk port uses IEEE 802.1Q tagging to carry multiple VLANs simultaneously across a single physical link between switches.
- Inter-switch links that must transport multiple VLANs require trunk ports to allow VLAN traffic segregation and forwarding.
- Configuring an inter-switch link as an access port limits traffic to the assigned VLAN, blocking all other VLANs from passing.
- VLAN tagging is essential for switches to identify and forward frames belonging to different VLANs over trunk links.
- A misconfigured access port on an inter-switch link causes VLAN traffic other than the access VLAN to fail, despite link status being up.
- Understanding the difference between access and trunk port modes is critical for proper VLAN design and troubleshooting in Cisco networks.
- Switchport mode misconfiguration is a common cause of VLAN communication failures in multi-VLAN environments.
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.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
FAQ
Questions learners often ask
What does this 200-301 question test?
A switchport configured as an access port carries traffic for only one VLAN and does not tag frames with VLAN IDs.
What is the correct answer to this question?
The correct answer is: The interface is carrying only VLAN 10 because an access port does not transport multiple VLANs like a trunk. — The most likely explanation is that the interface is carrying only the single access VLAN instead of acting as a trunk. In plain language, because the port is configured as an access port in VLAN 10, traffic for VLAN 10 works, but VLANs 20 and 30 cannot traverse the link. The physical connection may look healthy, but the logical switchport role is wrong for an inter-switch multi-VLAN design. This is a classic trunk-versus-access mistake. The correct answer is the one focused on the fact that an access port normally carries one VLAN only.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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