Which DTP switch port mode allows the port to create a trunk link if the neighboring port is in trunk mode, dynamic desirable mode, or desirable auto mode?

Question:
Which DTP switch port mode allows the port to create a trunk link if the neighboring port is in trunk mode, dynamic desirable mode, or desirable auto mode?

• trunk
• access
• dynamic desirable
• dynamic auto

Explanation: The Dynamic Trunking Protocol (DTP) is a proprietary networking protocol developed by Cisco for the purpose of negotiating trunking on a link between two switches, and for negotiating the type of trunking encapsulation to be used.

In dynamic auto mode, the interface is able to convert the link to a trunk link. The interface becomes a trunk interface if the neighboring interface is set to trunk or desirable mode. The default switchport mode for newer Cisco switch Ethernet interfaces is dynamic auto. Note that if two Cisco switches are left to the common default setting of auto, a trunk will never form.

In dynamic desirable mode, the interface actively attempt to convert the link to a trunk link. The interface becomes a trunk interface if the neighboring interface is set to trunk, desirable, or auto mode. This is the default switchport mode on older switches, such as the Catalyst 2950 and 3550 Series switches -> This is the best answer in this question.

Reference: http://www.ciscopress.com/articles/article.asp?p=2181837&seqNum=8

Exam with this question: CCNA v3.0 (200-125) Study Guide – Exam Dumps