Network+ Ethernet Switching and VLANs Flashcards

Which EtherChannel negotiation protocol is an open IEEE standard?

Answer: LACP

Link Aggregation Control Protocol (LACP), defined in IEEE 802.3ad, is the open standard for negotiating EtherChannel (link aggregation) bundles.

What is the maximum number of active links supported in an 802.3ad LACP EtherChannel bundle?

Answer: 8

IEEE 802.3ad LACP supports up to 8 active links in a bundle, with up to 8 additional standby links ready to take over if an active link fails.

A switch is configured with storm control. Which type of traffic does storm control mitigate?

Answer: Broadcast, multicast, and unknown unicast floods

Storm control monitors broadcast, multicast, and unknown unicast traffic rates and blocks or throttles them when they exceed configured thresholds to prevent broadcast storms.

Which spanning tree enhancement prevents a designated port from reverting to a root port if BPDUs stop being received?

Answer: Loop guard

Loop guard keeps a port in the inconsistent (blocking) state if BPDUs stop arriving, preventing a unidirectional link failure from causing a switching loop.

What does a Layer 3 switch use to route traffic between VLANs without an external router?

Answer: Switched Virtual Interfaces (SVIs)

Switched Virtual Interfaces (SVIs) are logical layer-3 interfaces on a Layer 3 switch, one per VLAN, that enable inter-VLAN routing internally.

Double tagging is a form of VLAN hopping. What condition makes a switch vulnerable to double-tag attacks?

Answer: The native VLAN matches the attacker's VLAN

Double-tag VLAN hopping works when the attacker's access VLAN matches the native VLAN of the trunk; the outer tag is stripped by the first switch, and the inner tag directs the frame to the target VLAN.

Which command-line verification method on a Cisco switch shows all VLANs and which ports are assigned to each?

Answer: show vlan brief

'show vlan brief' displays a concise list of all VLANs, their status, and port assignments on a Cisco switch.