Cisco CCNA mock exam questions sample test – Question 245

How many collision domains are in a LAN with four hubs and two bridges that are connected directly to each other, as shown in the following figure? (Click the Exhibit(s) button.)
A. four
B. five
C. six
D. fourteen

Correct Answer: B

A bridge segments the LAN into separate collision domains. The figure in this scenario has five segments created between these two bridges. Therefore, there will be five collision domains (segments) on the LAN if the two bridges are directly connected as shown in the exhibit. Hubs do not create LAN segments; they act as port aggregators and signal amplifiers.
It is also worth noting that with no router in the diagram, the entire network is a single broadcast domain. If a router were present, each of its interfaces could host a different subnet and each of those same interfaces would be a separate broadcast domain.

LAN Switching Fundamentals
Describe and verify switching concepts
Internetwork Design Guide — Designing Switched LAN Internetworks > Comparison of LAN Switches and Routers