CCNA Network Services and Security Practice Question
A switch interface connected to a Cisco IP phone with a PC behind it must carry voice and data correctly. Which two switchport commands are appropriate on that access port?
⚠ Common exam trap
Don't confuse trunk mode with the need for VLAN tagging; access ports can handle both data and voice VLANs without being trunks.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
switchport access vlan 10
The access VLAN carries the workstation data traffic, and the voice VLAN carries tagged voice traffic for the IP phone. That is the standard campus switchport design for a phone with a PC behind it. The port itself remains an access port, but the two most directly relevant commands here are the access VLAN and voice VLAN assignments.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
switchport mode trunk
Why it's wrong here
The 'switchport mode trunk' command forces the port to use 802.1Q trunking and expects all traffic to be tagged, which is not appropriate for a standard phone-plus-PC access port. In Cisco's recommended deployment, the switchport remains an access port: the PC transmits untagged frames, while the IP phone is configured to tag voice frames into the voice VLAN. Trunk mode would require manual VLAN pruning and is unnecessary for this single-user edge topology.
When this WOULD be correct
In a scenario where the question specifies a need for a switch port to connect multiple VLANs for devices such as multiple IP phones or a mix of voice and data traffic across different VLANs, 'switchport mode trunk' would be the correct command to enable trunking.
- ✓
switchport access vlan 10
Why this is correct
The 'switchport access vlan 10' command sets the port's untagged VLAN for data frames, which is exactly how the connected PC should be carried. In the standard Cisco IP phone topology, the phone passes PC traffic through untagged while tagging its own voice frames on a separate VLAN. Assigning access VLAN 10 ensures the PC's traffic is placed in the correct data VLAN.
- ✓
switchport voice vlan 20
Why this is correct
The 'switchport voice vlan 20' command dedicates VLAN 20 for voice traffic and instructs the IP phone to tag its voice frames with 802.1Q header. This is critical when a Cisco IP phone is connected to a switchport because the phone and the PC share the same physical link yet must remain in separate Layer 2 domains. Without this command, the phone's voice traffic would fall into the access VLAN, breaking voice/data separation.
- ✗
channel-group 1 mode active
Why it's wrong here
The 'channel-group 1 mode active' command enables LACP EtherChannel to aggregate multiple physical links into a single logical bundle. On a single user-facing port carrying one PC and an IP phone, there is no second link to bundle, and EtherChannel does not solve the need to separate untagged PC traffic from tagged voice traffic. It is irrelevant to the required VLAN design.
When this WOULD be correct
In a different scenario where the question asks about configuring a switch port for an EtherChannel setup that aggregates multiple links for redundancy and increased bandwidth, 'channel-group 1 mode active' would be appropriate to enable LACP (Link Aggregation Control Protocol) for the EtherChannel.
- ✗
spanning-tree cost 1
Why it's wrong here
Setting a Spanning Tree PortFast or path cost via 'spanning-tree cost 1' only influences STP root-port selection and loop prevention. It does not assign VLAN membership or distinguish data versus voice traffic on the switchport. For a phone-plus-PC access port, the missing pieces are the data access VLAN and the separate voice VLAN, not any STP metric.
When this WOULD be correct
In a scenario where the exam question asks about optimizing Spanning Tree Protocol settings for a specific port, and the focus is on adjusting port costs to influence path selection in a redundant network topology, this command could be correct.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓switchport access vlan 10Correct answer▾
Why this is correct
The 'switchport access vlan 10' command sets the port's untagged VLAN for data frames, which is exactly how the connected PC should be carried. In the standard Cisco IP phone topology, the phone passes PC traffic through untagged while tagging its own voice frames on a separate VLAN. Assigning access VLAN 10 ensures the PC's traffic is placed in the correct data VLAN.
✗switchport mode trunkWrong answer — click to see why▾
Why this is wrong here
Configuring an access port as a trunk would cause the switch to expect 802.1Q tagging on all frames, but the PC behind the phone typically sends untagged frames. This would break connectivity for the PC unless the phone is configured to tag PC traffic, which is not standard.
★ When this WOULD be the correct answer
In a scenario where the question specifies a need for a switch port to connect multiple VLANs for devices such as multiple IP phones or a mix of voice and data traffic across different VLANs, 'switchport mode trunk' would be the correct command to enable trunking.
Why candidates choose this
Students might think that because the IP phone uses a tagged VLAN, the port must be a trunk. However, Cisco IP phones use a special voice VLAN feature on access ports, not a full trunk.
✗channel-group 1 mode activeWrong answer — click to see why▾
Why this is wrong here
The channel-group command is used to create an EtherChannel, which bundles multiple physical links into a single logical link. This is not relevant for a single access port connecting to an IP phone and PC, as there is only one physical link.
★ When this WOULD be the correct answer
In a different scenario where the question asks about configuring a switch port for an EtherChannel setup that aggregates multiple links for redundancy and increased bandwidth, 'channel-group 1 mode active' would be appropriate to enable LACP (Link Aggregation Control Protocol) for the EtherChannel.
Why candidates choose this
Students might confuse the need for additional bandwidth or redundancy on a user port, but EtherChannel is typically used on uplinks or server connections, not on edge ports.
✗spanning-tree cost 1Wrong answer — click to see why▾
Why this is wrong here
The spanning-tree cost command manually sets the STP path cost for a port, which is used for loop prevention. It does not affect VLAN assignment or voice/data separation, so it does not address the requirement of carrying voice and data correctly.
★ When this WOULD be the correct answer
In a scenario where the exam question asks about optimizing Spanning Tree Protocol settings for a specific port, and the focus is on adjusting port costs to influence path selection in a redundant network topology, this command could be correct.
Why candidates choose this
Students might think that adjusting STP cost is necessary for voice traffic to ensure fast convergence, but this is not a standard configuration for IP phone ports. Voice VLAN and QoS are the primary concerns.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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Key term
Access port
An access port is a switch port that connects to a single end device, like a computer or printer, and carries traffic for only one VLAN.
Key term
VLAN
A VLAN logically segments a physical network into isolated broadcast domains without requiring separate physical switches.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.