VLANs are powerful, but they require the right tagging protocol to work across multiple switches—and that’s where 802.1Q comes in. This episode explains how trunk ports carry traffic from multiple VLANs using VLAN tags inserted into Ethernet frames. You’ll learn how access ports differ from trunk ports, and why configuring native VLANs is important to avoid untagged traffic conflicts and security issues.

We also discuss Dynamic Trunking Protocol (DTP), the risks it poses, and why disabling unnecessary trunk negotiation is a best practice. Understanding tagging and trunking is essential when deploying multi-switch VLANs and connecting infrastructure like VoIP phones, which often require multiple VLANs on a single port. This topic regularly appears in both configuration labs and troubleshooting scenarios on the exam.