To carry VLANs between a Cisco switch and a third‑party switch, which trunk encapsulation should be configured?

IEEE 802.1q is the industry-standard trunking protocol, making it compatible with switches from different vendors, including third-party switches. It inserts a 4-byte tag into the Ethernet frame header to identify the VLAN. ISL (Inter-Switch Link) is a Cisco proprietary trunking protocol and would not be compatible with a third-party switch. DSCP (Differentiated Services Code Point) is used for Quality of Service (QoS) marking, not for VLAN trunking. IEEE 802.1p is part of the 802.1q standard and is used for QoS prioritization within a VLAN-tagged frame, not for the trunk encapsulation itself.