Dynamic Trunking Protocol (DTP) is a Cisco proprietary protocol used to automatically negotiate trunking between two switches. It helps determine whether a link should be a trunk or an access port, and if a trunk, which encapsulation (such as IEEE 802.1Q) to use. DTP simplifies VLAN configuration and management in network environments. https://www.uninets.com/blog/dynamic-trunking-protocol-dtp