Does a router decrease the number of collision domains?

Question

what are two characteristics of segmenting a network with a router ? ( choose two )

a. a router processes data more quickly than switches.
b. filtering can occur based on layer 3 information .
c. a router decrease the number of collision domains.
d. adding a router to the network decreases latency.
e. broadcasts are not forwarded across the router.

The answers are C and E. Shouldn't be B and E? As far as I know routers increase collision domains (as switches do).

Can anyone help out with this question? I've googled it and can't determine if they do decrease collision domains or don't? Also I know for sure filtering can occur on layer 3, but it says choose 2. Thanks!!!

Answer 1

B & E, you can filter on a router based on IP address and or port numbers, this will have the effect of making your broadcast domains smaller, hence less broadcasts per domain.



A router would actually increase collision domains, if you have one domain and split it into two and route between them with the router, you have now increased the number of domains. That's a trick answer.



E is true.



hope this helps!

Answer 2

Bridges (sometimes switches are bridges) and routers divide collision domains. Repeaters (sometimes switches are repeaters) propagate collisions.



Bridges forward broadcasts, routers do not forward broadcasts.



A collision occurs at layer 2 on an Ethernet network. Collisions are unique to Ethernet. (your first clue). Other LANs, like Token Ring don't have the concept of a collision.



When a router receives a packet the first thing it does is determine if the layer 2 (Ethernet) frame is valid. If yes, it discards the Ethernet frame and makes it's forwarding decision based on the layer 3 (IP or other L3 protocol) packet inside. When the router forwards the packet, assuming it's going out another Ethernet port it creates a new Ethernet frame using it's own MAC as the source address. Therefore routers are points of demarcation for the layer 2 network.



A bridge will forward the Ethernet frame unaltered providing the frame is valid. A bridge will learn MAC addresses off each port, then eventually control which ports it forwards on based on destination MAC address.



Router learns layer 3 addresses on off each port (using a routing protocol), it doesn't care so much about layer 2. That's why routers are used to connect LANs to WANs.

Answer 3

on your representation there are certainly 3 collision domain names, although there is likewise a million broadcast area. that's assuming that there are not any different Layer 2 or 3 gadgets on the subject remember of the swap. Rule of thumb is: a million. each and each energetic port is considered a collision area on a transformation. 2. each energetic router port is in its very own broadcast section. 3. each and each hub is a million collision area, regardless of how many ports it has. As there are not any non interior of sight vlans configured on your occasion there is just one broadcast area different than a router enters the section or separate vlans are created. do no longer assume there's a router, pondering in a flat (switched purely) community switches may be interconnected with their uplink ports, or have trunk ports configured to hook up with different switches in the get entry to layer. There is additionally many switches in the previous than hitting the distribution layer router(s), if a different LAN needs to be accessed for representation. Cisco use a hierarchical kind, with: a million.Switches on the get entry to Layer. 2.Routers and/or Multilayer Switches in the Distribution Layer, 3.physically powerful Routers on the middle Layer. desire this facilitates!