Cisco CCNA (200-301)Network AccessMedium
A network administrator is configuring a new switch, SW1, and wants to prevent unnecessary DTP frames from being sent on an access port connected to an end device. Which command sequence would achieve this goal?
- ASW1(config-if)# switchport mode access
- BSW1(config-if)# switchport mode dynamic auto SW1(config-if)# switchport nonegotiate
- CSW1(config-if)# switchport mode trunk SW1(config-if)# switchport nonegotiate
- DSW1(config-if)# switchport mode access SW1(config-if)# switchport nonegotiate
Show answer & explanationAnswer & explanation
Correct answer: A. SW1(config-if)# switchport mode access
When a port is explicitly configured as an access port using `switchport mode access`, DTP is disabled by default, preventing DTP frames from being sent. The `switchport nonegotiate` command is typically used with `switchport mode trunk` to disable DTP on a trunk port.
Why the other options are wrong
- B. `dynamic auto` is a DTP mode that would actively send or listen for DTP frames.
- C. This configures a trunk port and disables DTP on it, but the goal is an access port.
- D. `switchport nonegotiate` is not applicable or necessary for an access port; `switchport mode access` implicitly disables DTP.
Dynamic Trunking Protocol (DTP)
A Cisco proprietary protocol used to negotiate trunking between two directly connected switches. It can dynamically change a port's operational mode to trunk or access.
- DTP operates in modes: desirable, auto, on, off, nonegotiate.
- It can lead to security risks if not properly managed.
- `switchport mode access` implicitly disables DTP negotiation.
Memory trick: No DTP chat: Access or Trunk 'nonegotiate'.