Which two of the following are advantages of Layer 2 Ethernet switches over hubs? (Choose two.)
A.
To increase the size of broadcast domains
B.
To filter frames according to MAC addresses
C.
To allow simultaneous frame transmissions
D.
To increase the maximum length of UTP cabling between devices
E.
decreasing the number of collision domains
F.
increasing the size of broadcast domains
Explanation:
A hub is a broadcast domain and a collision domain, while a switch is a broadcast domain, each interface is a collision domain. The switch is a device of data link layer, forwards and floods data frames based on the MAC address. The hub adopts the shared bandwidth working mode, while the switch adopts dedicated bandwidth.
С – is not correct. B & E – correct.
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Every switchport on a switch IS a collision domain. Adding switchports and switches increases the number of collision domains. Its better to have 24 collision domains on a LAN (on a 24 port switch), than to have 24 hosts in one collision domain (on a 24 port hub). Only one frame can be transmitted at a time on the hub as all the ports share the collision domain. If two hosts transmit frames at the same time on the same hub the result is a collision. The hosts are force to wait and try again.
Because each switchport on a switch creates its own collision domain it allows each collision domain on the swtich to freely transmit frames at the same time other frames are being transmitted in other collision domains (other switchports). The frames don’t collide.
The answer is B and C.
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