Ccna certification Practice Tests

257

 3.  A.  A collision domain is defined as a group of computers that can potentially have a frame 

collision. Adding switches that can negotiate full-duplex and forward/filter fixes these 

issues. The potential of receiving layer 2 and layer 3 broadcast messages can increase the 

number of collisions. Layer 2 and layer 3 broadcasts do not create collision domains since 

unicast messages can also cause collisions. It is more common to see computers in collision 

domains set to 10 Mb/s half-duplex, not full-duplex.

 4.  A.  Currently all of the computers are within one giant collision domain. Replacing the 

hub with a switch will create four separate potential collision domains. Switches create 

micro-segmentation, which increases the number of collision domains and increases 

bandwidth. The number of collision domains would only decrease if you swapped a switch 

for a hub, thus creating one collision domain. The number of broadcast domains would 

be unaffected using either a switch or a hub unless a router was used for routing between 

VLANs.

 5.  C.  In the exhibit there are two broadcast domains, VLAN 1 and VLAN 2. In each of 

the broadcast domains there exists a single collision domain, along with the collision 

domain between the switch and router. Therefore, three collision domains exist with two 

broadcast domains. One collision domain with one broadcast domain would only be true 

if the switch was replaced with a hub and VLANs were not used. Two collision domains 

with one broadcast domain would only be true if the hubs were directly connected 

together and VLAN routing was not in use. Seven collision domains existing with two 

broadcast domains would only be true if the hubs were swapped out for switches.

Collision Domain

Collision Domain

Collision Domain

Broadcast Domain

Broadcast Domain

VLAN 2

VLAN 1

Hub

Hub

Router

Switch

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