A network administrator checks the operational state of link GigabitEthernet0/1 connecting two switches, SW-Core and SW-Access. Both switch interfaces are operating with default factory switchport settings, which sets their Dynamic Trunking Protocol (DTP) mode to dynamic auto. Which two outcomes describe the state of this connection? (Select two.)
- The interface operationally functions as a Layer 2 access port in VLAN 1.Answer
- BAn IEEE 802.1Q trunk forms automatically, but frames belonging to VLAN 1 are dropped due to a native VLAN mismatch.
- To establish an active trunk connection using dynamic negotiation, at least one interface must be configured as dynamic desirable.Answer
- DExecuting the command spanning-tree portfast on GigabitEthernet0/1 will force the DTP state machine to negotiate an 802.1Q trunk.
Answer
The interface operationally functions as a Layer 2 access port in VLAN 1, and establishing a trunk via dynamic negotiation requires at least one interface to be set to dynamic desirable.
When both ends of a switch-to-switch link operate in default dynamic auto mode, neither switch interface sends DTP negotiation packets to initiate a trunk. Consequently, the operational status of both ports remains in access mode operating in the default VLAN 1. For dynamic trunking negotiation to succeed, at least one of the connected interfaces must actively request a trunk by being configured in dynamic desirable mode.
Step-by-Step Solution
Key Concept
DTP mode negotiation combinations and operational defaults for 802.1Q trunks