Valid operational modes for a VLAN trunk port When configuring a Cisco switch port to operate as a VLAN trunk, which of the following port modes are valid in that trunking context (choose the correct grouping)?

Introduction / Context:
Cisco switch ports can operate in different administrative modes related to trunk negotiation and access behavior. Understanding which modes actually pertain to trunking prevents configuration mistakes and helps you interpret show interfaces switchport outputs correctly. The options listed include both legitimate trunk negotiation modes and unrelated states from other protocols.

Given Data / Assumptions:

• The modes presented are: Blocking, Dynamic auto, Dynamic desirable, Nonegotiate, Access, Learning.
• We must choose those that are valid modes used when a port is set up as, or negotiates, a trunk.

Concept / Approach:

Trunk-related administrative modes include dynamic auto (passively waits to form a trunk), dynamic desirable (actively tries to form a trunk), trunk (force trunk), and nonegotiate (do not run DTP; requires the far end to be hard-set). The options do not include the literal trunk keyword but do include the other relevant trunk-related modes. STP states such as blocking and learning are not port trunk modes, and access forces non-trunk operation.

Step-by-Step Solution:

Verification / Alternative check:

Command reference for switchport mode confirms valid options such as access, trunk, dynamic auto, dynamic desirable, and the switchport nonegotiate modifier for trunk links.

Why Other Options Are Wrong:

• Blocking and Learning are STP states, not trunk modes.
• Access is specifically non-trunk.
• Other groupings include at least one invalid trunk-mode choice.

Common Pitfalls:

• Confusing STP states with port mode settings.
• Using nonegotiate on one side without hard-setting trunk on the peer.

Final Answer:

2, 3 and 4