Which two characteristics apply to Layer 2 switches? (Choose two.)
A.
Increases the number of collision domains
B.
Decreases the number of collision domains
C.
Implements VLAN
D.
Decreases the number of broadcast domains
E.
Uses the IP address to make decisions for forwarding data packets
– a switch is a multi-interface hub, every interface on a switch is a collision domain. A 24 interfaces switch creates 24 collision domains (assuming every interface is connected to something, VLAN don’t have any importance here since VLANs are a layer 2 concept, not layer 1 like collision domains)
Broadcast Domains
– layer 2 of the OSI model
– a switch creates an entire broadcast domain (provided that there’s only one VLAN) since broadcasts are a layer 2 concept (mac address related)
– routers don’t forward layer 2 broadcasts, hence they separate broadcast domains
A virtual LAN (VLAN) is any broadcast domain that is partitioned and isolated in a computer network at the data link layer (OSI layer 2).[1][2] LAN is an abbreviation of local area network.
To subdivide a network into virtual LANs, one configures a network switch or router. Simpler network devices can only partition per physical port (if at all), in which case each VLAN is connected with a dedicated network cable (and VLAN connectivity is limited by the number of hardware ports available). More sophisticated devices can mark packets through tagging, so that a single interconnect (trunk) may be used to transport data for multiple VLANs. Since VLANs share bandwidth, a VLAN trunk might use link aggregation and/or quality of service prioritization to route data efficiently.
VLANs allow network administrators to group hosts together even if the hosts are not on the same network switch. This can greatly simplify network design and deployment, because VLAN membership can be configured through software. Without VLANs, grouping hosts according to their resource needs necessitates the labor of relocating nodes or rewiring data links.