In a Cisco network environment, when using Dynamic Trunking Protocol (DTP) to establish trunk links between switches, it is crucial that the native VLAN matches on both ends of the trunk link.The native VLAN is used for untagged traffic that crosses the trunk link. If there is a mismatch in the native VLAN configuration between two interconnected switches, as indicated by the "CDP-4-NATIVE_VLAN_MISMATCH" error message in the exhibit, management traffic or other untagged traffic on VLAN1 will not pass through. To resolve this issue, an engineer must configure both sides of the trunk link to have the same native VLAN ID. This ensures that untagged traffic can be correctly forwarded across the network.