Network+ Ethernet Switching and VLANs Flashcards
7 cards from real COMPTIA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Network+ Ethernet Switching and VLANs flashcards as text
A switch receives a frame destined for a MAC address not in its CAM table. What does it do?
Answer: Floods the frame out all ports except the receiving port
When a switch cannot find a destination MAC in its CAM table, it floods the frame out all ports except the one it arrived on — this is called unknown unicast flooding.
Which IEEE standard defines the 802.1Q VLAN tagging mechanism?
Answer: IEEE 802.1Q
IEEE 802.1Q defines the standard for VLAN tagging, inserting a 4-byte tag into Ethernet frames to carry VLAN membership information across trunk links.
What is the size of the VLAN ID field in an 802.1Q tag?
Answer: 12 bits
The 802.1Q VLAN ID field is 12 bits, supporting VLAN IDs from 0 to 4095 (4,096 possible VLANs).
A port configured as an access port receives a frame with an 802.1Q tag. What should a properly configured switch do?
Answer: Drop the frame
Access ports expect untagged frames; a tagged frame arriving on an access port is typically dropped as it indicates a misconfiguration or security issue.
Which spanning tree port state allows a port to learn MAC addresses but NOT forward user traffic?
Answer: Learning
The Learning state allows the switch to populate its MAC address table from incoming frames but does not yet forward user data traffic.
What type of switch port carries traffic for multiple VLANs simultaneously?
Answer: Trunk port
A trunk port carries tagged traffic for multiple VLANs simultaneously, typically used for switch-to-switch or switch-to-router links.
Which attack exploits the switch's default behavior of adding all VLANs to trunk ports?
Answer: VLAN hopping
VLAN hopping exploits dynamic trunking or double-tagging to gain access to VLANs the attacker should not be on, bypassing VLAN segmentation.