Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
Which statement best explains why trunks are needed between switches in a multi-VLAN environment?
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
They allow multiple VLANs to share one physical inter-switch link while preserving VLAN identity
This is correct because trunking allows multiple VLANs to traverse a single physical link with tagging.
B
Distractor review
They force every host port to become a routed port
This is wrong because trunks are about carrying multiple VLANs, not converting all host ports into routed interfaces.
C
Distractor review
They eliminate the need for VLAN tagging
This is wrong because trunking commonly depends on tagging precisely so multiple VLANs can be distinguished.
D
Distractor review
They replace the need for IP addressing on switches
This is wrong because trunks are a Layer 2 transport concept and do not remove the need for IP addressing where required.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is selecting answers that confuse trunk ports with routed ports or suggest trunks eliminate VLAN tagging. Some candidates mistakenly believe trunks convert all host ports into routed interfaces or that VLAN tagging is unnecessary on trunks. In reality, trunk ports remain Layer 2 interfaces and rely on VLAN tagging (802.1Q) to distinguish traffic from different VLANs. Misreading this can cause candidates to pick incorrect options that mention routed ports or claim trunks remove the need for tagging, which contradicts fundamental VLAN trunking principles.
Technical deep dive
How to think about this question
In a multi-VLAN environment, switches segment network traffic into separate broadcast domains called VLANs to improve security and reduce congestion. Each VLAN acts like a distinct logical network, isolating traffic from other VLANs. However, when multiple switches are involved, VLAN traffic must traverse links between switches while maintaining VLAN separation. This is where trunk links come into play, allowing multiple VLANs to share a single physical connection by tagging frames with VLAN identifiers using protocols like IEEE 802.1Q. The decision to use trunks stems from the need to efficiently carry traffic from multiple VLANs over one inter-switch link without losing VLAN identity. Trunking tags each frame with a VLAN ID, enabling the receiving switch to correctly forward the frame to the appropriate VLAN. Without trunks, each VLAN would require a dedicated physical link between switches, which is impractical and wasteful in larger networks. Cisco switches use 802.1Q as the standard trunking protocol, and understanding this is critical for CCNA candidates. A common exam trap is confusing trunk links with routed ports or thinking trunks eliminate VLAN tagging. Trunks do not convert switch ports into Layer 3 routed interfaces; they operate at Layer 2 and rely on tagging to distinguish VLAN traffic. Misunderstanding this can lead to selecting incorrect answers that mention routed ports or no tagging. Practically, trunks enable scalable VLAN deployment across multiple switches, preserving VLAN separation while minimizing cabling complexity.
KKey Concepts to Remember
- A trunk link allows multiple VLANs to share a single physical inter-switch connection by tagging frames with VLAN identifiers.
- Cisco switches use IEEE 802.1Q as the standard protocol to tag VLAN traffic on trunk links.
- Without trunking, each VLAN would require a separate physical link between switches, which is inefficient and impractical.
- Trunk ports operate at Layer 2 and do not convert switch ports into routed (Layer 3) interfaces.
- VLAN tagging on trunks preserves VLAN identity, enabling switches to forward frames to the correct VLAN across shared links.
- Trunking improves network scalability by reducing the number of physical cables needed to support multiple VLANs between switches.
- Misunderstanding trunking can lead to confusing it with routed ports or assuming VLAN tagging is unnecessary on trunks.
- In Cisco networks, trunk ports are configured explicitly to carry multiple VLANs, unlike access ports which carry only one VLAN.
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 trunk link allows multiple VLANs to share a single physical inter-switch connection by tagging frames with VLAN identifiers.
What is the correct answer to this question?
The correct answer is: They allow multiple VLANs to share one physical inter-switch link while preserving VLAN identity — Trunks are needed because they allow traffic from multiple VLANs to cross a single physical link between switches. In plain language, instead of using one cable per VLAN between switches, a trunk can carry many VLANs at once while preserving their identity through tagging. That makes the design much more scalable and practical in real networks. Without trunking, only one VLAN’s traffic could normally use a simple access link at a time. In larger environments, that would quickly become messy and wasteful. CCNA questions often focus on this basic reason for trunks: efficient transport of multiple logically separate VLANs over one physical inter-switch connection.
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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