Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A switch port connected to a user PC should be placed in VLAN 20 and must not negotiate trunking. Which configuration is the most appropriate?
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
switchport mode access switchport access vlan 20
This is correct because it explicitly makes the port an access port in VLAN 20.
B
Distractor review
switchport mode trunk switchport trunk native vlan 20
This is wrong because it makes the port a trunk instead of a one-VLAN host port.
C
Distractor review
switchport mode dynamic desirable switchport trunk allowed vlan 20
This is wrong because it still allows DTP trunk negotiation behavior.
D
Distractor review
no switchport ip address 192.168.20.1 255.255.255.0
This is wrong because it converts the port into a Layer 3 routed interface on supported platforms.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is choosing a configuration that leaves Dynamic Trunking Protocol (DTP) enabled, such as 'switchport mode dynamic desirable', which allows the port to negotiate trunking. This can cause the port to become a trunk unexpectedly, exposing multiple VLANs to a user device and creating security risks. Another trap is configuring the port as a trunk with 'switchport mode trunk', which is inappropriate for a user PC connection because it carries multiple VLANs and requires the device to understand VLAN tags, which most PCs do not. Lastly, using 'no switchport' converts the interface into a Layer 3 routed port, removing VLAN membership and preventing normal Layer 2 switching behavior expected for user ports.
Technical deep dive
How to think about this question
VLANs (Virtual Local Area Networks) segment a physical switch into multiple logical networks, isolating broadcast domains. Switch ports can operate in access mode, carrying traffic for a single VLAN, or trunk mode, carrying traffic for multiple VLANs tagged with IEEE 802.1Q headers. Access ports send and receive untagged frames, associating all traffic with a single VLAN. This behavior is essential for end-user devices like PCs that do not understand VLAN tagging. The command 'switchport mode access' explicitly sets the port to access mode, disabling Dynamic Trunking Protocol (DTP) negotiation. DTP is Cisco's proprietary protocol that dynamically negotiates trunk links between switches. While useful for switch-to-switch links, DTP can cause unintended trunk formation on user ports if left enabled, leading to security vulnerabilities and VLAN leakage. Assigning 'switchport access vlan 20' binds the port to VLAN 20, ensuring all untagged frames are handled within that VLAN. A common exam trap is selecting configurations that enable trunking or convert the port to Layer 3 mode. For example, 'switchport mode trunk' or 'switchport mode dynamic desirable' allows trunk negotiation, which is inappropriate for user PC ports. Similarly, 'no switchport' converts the interface into a routed port, removing VLAN membership and disabling Layer 2 switching features. Understanding these distinctions prevents misconfiguration and aligns with best practices for secure and predictable network design.
KKey Concepts to Remember
- A switch port configured as an access port carries traffic for only one VLAN and does not participate in VLAN trunking protocols.
- The command 'switchport mode access' forces a switch port to operate as a non-trunking access port, preventing Dynamic Trunking Protocol (DTP) negotiation.
- Assigning a VLAN to an access port with 'switchport access vlan <vlan-id>' ensures all untagged frames on that port belong to the specified VLAN.
- Dynamic Trunking Protocol (DTP) enables automatic negotiation of trunk links but can cause unintended trunk formation if not explicitly disabled.
- Configuring a port as a trunk with 'switchport mode trunk' allows multiple VLANs to traverse the link, which is inappropriate for user PC connections.
- Using 'no switchport' converts a switch port into a Layer 3 routed interface, which is unsuitable for typical end-user PC connections requiring VLAN membership.
- Explicitly configuring access ports improves network security and stability by eliminating unexpected VLAN tagging or trunk negotiation behaviors.
- A user-facing switch port should never rely on dynamic trunk negotiation to avoid accidental VLAN leakage or security risks.
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
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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
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 switch port configured as an access port carries traffic for only one VLAN and does not participate in VLAN trunking protocols.
What is the correct answer to this question?
The correct answer is: switchport mode access switchport access vlan 20 — The most appropriate configuration is to force the interface into access mode and assign it to VLAN 20. In practical terms, a normal user-facing switch port is supposed to carry one VLAN only. There is no reason to rely on dynamic trunk negotiation for a desktop or laptop connection. Explicit access-port configuration is cleaner, more predictable, and safer. This is a common switching best-practice question. The wrong answers usually leave room for unwanted trunking behavior or move the interface into a completely different role. The right answer combines the correct port role with the correct VLAN membership.
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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