Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
Exhibit
Interface config: switchport mode access switchport access vlan 10 spanning-tree portfast
Exhibit: A switch interface connected to an IP phone and PC is configured as an access port in VLAN 10. The PC works, but the phone does not register. What additional configuration is most likely needed?
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
Distractor review
switchport trunk encapsulation dot1q
Distractor.
B
Best answer
switchport voice vlan <voice-vlan-id>
Correct choice.
C
Distractor review
channel-group 1 mode active
Distractor.
D
Distractor review
ip helper-address on the switchport
Distractor.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is selecting the switchport trunk encapsulation dot1q command, mistakenly believing that trunking is required for voice VLAN support. However, voice VLANs operate on access ports by tagging voice traffic separately without converting the port into a trunk. Another trap is confusing channel-group commands with voice VLAN configuration; EtherChannel bundles links but does not segregate voice traffic. Additionally, candidates might incorrectly think that IP helper-address on the switchport will resolve registration issues, but this command only forwards DHCP requests and does not affect VLAN tagging. Understanding that voice VLAN is a distinct feature for tagging voice traffic on access ports is critical to avoid these mistakes.
Technical deep dive
How to think about this question
In Cisco switching environments, when an IP phone and a PC share a single switch port, the port must handle two types of traffic: untagged data traffic from the PC and tagged voice traffic from the IP phone. The switchport configured as an access port assigns untagged frames to a single VLAN, typically the data VLAN. However, IP phones require a separate voice VLAN to segregate voice traffic, which is tagged with a specific VLAN ID to ensure quality of service and proper traffic separation. The command switchport voice vlan <voice-vlan-id> configures the switch port to recognize and tag voice traffic with the specified VLAN ID. This allows the switch to differentiate voice packets from data packets, forwarding voice traffic on the voice VLAN while the PC continues to use the access VLAN. Without this configuration, the IP phone cannot properly register with the voice gateway or call manager because its voice traffic is not correctly tagged or separated. A common exam trap is to assume that simply configuring the port as an access port is sufficient for both devices. Candidates may mistakenly select commands related to trunking or channel groups, which do not address voice VLAN requirements. Practically, the voice VLAN feature enables seamless coexistence of voice and data on a single physical port, ensuring IP phones function correctly without disrupting PC connectivity.
KKey Concepts to Remember
- A switchport configured with switchport voice vlan <voice-vlan-id> tags voice traffic separately from the data VLAN to support IP phone registration and call signaling.
- An access port assigns untagged frames to a single VLAN, which is insufficient for handling both PC data and IP phone voice traffic on the same port.
- Voice VLAN tagging enables quality of service (QoS) prioritization and traffic separation for IP phone voice packets within a Cisco network.
- Without the voice VLAN configuration, IP phones fail to register because their voice traffic is not correctly identified or segregated by the switch.
- The switchport trunk encapsulation dot1q command is irrelevant on access ports and does not enable voice VLAN functionality.
- Channel-group commands configure EtherChannel and do not affect voice VLAN or IP phone registration on a single access port.
- IP helper-address commands are used for DHCP relay and do not influence VLAN tagging or voice traffic handling on switchports.
- Cisco switches use the voice VLAN feature to allow a single physical port to carry both tagged voice and untagged data traffic simultaneously.
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
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Question 5
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Question 6
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FAQ
Questions learners often ask
What does this 200-301 question test?
A switchport configured with switchport voice vlan <voice-vlan-id> tags voice traffic separately from the data VLAN to support IP phone registration and call signaling.
What is the correct answer to this question?
The correct answer is: switchport voice vlan <voice-vlan-id> — An IP phone commonly requires a voice VLAN so tagged voice traffic is separated from the data VLAN used by the attached PC. Without a voice VLAN, the PC can still work on the access VLAN while the phone fails to register properly.
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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