Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A switchport connected to another switch is configured with `switchport mode dynamic auto` on both ends. What is the most likely outcome if neither side actively negotiates trunking?
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 link is likely to remain non-trunking because both sides are waiting passively.
This is correct because dynamic auto on both ends does not normally force trunk formation.
B
Distractor review
The link always becomes a trunk immediately.
This is wrong because dynamic auto is passive, not a forced trunk mode.
C
Distractor review
The link becomes a routed Layer 3 link.
This is wrong because DTP behavior does not convert the switchport into a routed interface.
D
Distractor review
All VLANs are deleted from both switches.
This is wrong because DTP negotiation does not delete VLANs.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is assuming that configuring both switchports as dynamic auto will automatically create a trunk link. Because dynamic auto is a passive mode, neither side initiates trunk negotiation, so the link remains an access port. Candidates often confuse dynamic auto with dynamic desirable, which actively negotiates trunking. This misunderstanding leads to selecting incorrect answers that claim the link becomes a trunk immediately. Remember, without at least one side actively requesting trunking, DTP negotiation will not succeed, and the link stays non-trunking.
Technical deep dive
How to think about this question
Dynamic Trunking Protocol (DTP) is a Cisco proprietary protocol used to negotiate trunk links between switches. It automates the process of trunk formation by exchanging DTP frames to agree on whether a link should be a trunk or access port. The main DTP modes are dynamic auto, dynamic desirable, trunk, and access. Dynamic auto mode is passive; it waits for the other side to initiate trunk negotiation but does not actively try to form a trunk itself. When both ends of a switch-to-switch link are configured with switchport mode dynamic auto, neither side actively attempts to form a trunk. Both interfaces wait passively for the other to initiate the negotiation. Because no side sends DTP frames to actively request trunking, the link remains in access mode by default. To successfully form a trunk using DTP, at least one side must be set to dynamic desirable or trunk mode to actively negotiate trunking. This behavior often confuses candidates who assume dynamic auto will automatically form trunks. The exam trap lies in misunderstanding the passive nature of dynamic auto mode and expecting trunk formation without active negotiation. In practical networks, to ensure trunk links form reliably, network engineers configure one side as dynamic desirable or trunk mode. This prevents link misconfigurations and ensures VLAN traffic is properly carried across the trunk.
KKey Concepts to Remember
- Dynamic Trunking Protocol (DTP) automates trunk negotiation between Cisco switches by exchanging negotiation frames.
- The dynamic auto mode is passive and waits for the other side to initiate trunk negotiation but does not initiate it itself.
- A trunk link forms automatically only if at least one side is configured as dynamic desirable or trunk mode to actively negotiate.
- When both ends are set to dynamic auto, the link remains in access mode because neither side initiates trunk negotiation.
- DTP does not convert switchports into routed Layer 3 interfaces; it only negotiates trunk or access Layer 2 modes.
- VLAN configurations are not deleted or affected by DTP negotiation failures or modes.
- Understanding the difference between active and passive DTP modes is critical to correctly configuring trunk links in Cisco networks.
- Misconfiguring both ends as dynamic auto leads to a non-trunking link, which can cause VLAN traffic segregation issues.
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?
Dynamic Trunking Protocol (DTP) automates trunk negotiation between Cisco switches by exchanging negotiation frames.
What is the correct answer to this question?
The correct answer is: The link is likely to remain non-trunking because both sides are waiting passively. — If both ends are set to dynamic auto, the most likely outcome is that the link does not become a trunk automatically. In plain language, both interfaces are waiting passively for the other side to initiate the negotiation. Since neither side is actively trying to form the trunk, the link typically remains non-trunking unless one side is changed to a more active mode or trunk is configured directly. This is a classic DTP behavior question because it tests whether you understand the difference between active and passive negotiation roles. The correct answer is the one that reflects the passive nature of dynamic auto on both sides.
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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