Dynamic trunk is not a DTP mode. DTP is a Cisco proprietary trunk negotiation protocol and is used to determine if two interfaces on connected devices can
become a trunk. There are five modes of DTP:
* Trunk: Puts the interface into permanent trunking mode and negotiates to convert the link into a trunk link. The interface becomes a trunk interface even if the neighboring interface does not agree to the change.
* Access: Puts the interface into permanent nontrunking mode and negotiates to convert the link into a nontrunk link. The interface becomes a nontrunk interface even if the neighboring interface does not agree to the change.
* Dynamic desirable: Makes 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.
* Dynamic auto: Makes the interface willing 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. This is the default mode for all Ethernet interfaces in Cisco IOS.
* Nonegotiate: Puts the interface into permanent trunking mode but prevents the interface from generating DTP frames. You must configure the neighboring interface manually as a trunk interface to establish a trunk link. Use this mode when connecting to a device that does not support DTP.

If one side's mode of link is in trunk mode, dynamic desirable mode, or dynamic auto mode, and the other side is trunk or dynamic desirable, a trunk will form. Nonegotiate mode enables trunking but disables DTP.