The correct answer is that the Dynamic Trunking Protocol (DTP) is used to automatically negotiate trunking between two Cisco switches. This is a Cisco proprietary protocol that allows switch ports to dynamically determine whether to operate as an access port or a trunk port, eliminating the need for manual trunk configuration when both ends are set to compatible DTP modes like dynamic desirable or dynamic auto. On the ENCOR 350-401 exam, this concept tests your understanding of Layer 2 switchport negotiation and the common pitfall is assuming DTP is an industry standard—it is not, and it can pose a security risk if left enabled on ports connected to non-Cisco devices. A strong memory tip is to think of DTP as the “automatic handshake” for trunking: if both sides say “yes” (dynamic desirable), a trunk forms; if one says “maybe” (dynamic auto) and the other says “yes,” it still works, but if both say “maybe,” the link stays an access port.
CCNP VLANs and Trunking Practice Question
This 350-401 practice question tests your understanding of vlans and trunking. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
What is the purpose of the Dynamic Trunking Protocol (DTP) on Cisco switches?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
To automatically negotiate trunking between two Cisco switches.
DTP (Dynamic Trunking Protocol) is a Cisco proprietary protocol used to automatically negotiate the operational mode (access or trunk) of a switch port between two Cisco switches. When both ends are configured with DTP modes like dynamic desirable or dynamic auto, the link can become a trunk without manual configuration, simplifying deployment in environments where trunking is needed.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
To automatically negotiate trunking between two Cisco switches.
Incorrect. Loop prevention is handled by Spanning Tree Protocol (STP).
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse DTP with VTP (VLAN Trunking Protocol), which manages VLAN database propagation, or assume DTP provides security features like encryption, when in fact it only negotiates trunking and can be a security risk.
Detailed technical explanation
How to think about this question
DTP operates using Cisco's proprietary frames (type 0x2003) exchanged between switches to negotiate trunking states: access, trunk, dynamic desirable, dynamic auto, and nonegotiate. A common real-world pitfall is that DTP can be exploited by attackers to gain trunk access (VLAN hopping), so best practice is to disable DTP on ports that should remain access ports using 'switchport nonegotiate' or setting the port to 'switchport mode access'.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
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.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
VLANs and Trunking — This question tests VLANs and Trunking — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: To automatically negotiate trunking between two Cisco switches. — DTP (Dynamic Trunking Protocol) is a Cisco proprietary protocol used to automatically negotiate the operational mode (access or trunk) of a switch port between two Cisco switches. When both ends are configured with DTP modes like dynamic desirable or dynamic auto, the link can become a trunk without manual configuration, simplifying deployment in environments where trunking is needed.
What should I do if I get this 350-401 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This 350-401 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 350-401 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.