In this post, I will discuss about new CCNA exam 200-120, ICND1 100-101, ICND2 200-101 questions. I ‘ll focus on Internetworking Basic questions, especially on broadcast and collision domains.
What that you must learned about the Broadcast and collision domain?

Collision Domain, when some computers that are connected to a hub device, if one device sends out a packet on a network segment and thereby forces every other device that is connected to the same hub to pay attention to it.

All devices connected to the hub are in the same physical network segment. In an ethernet network, all devices that are members of the same physical network segment will always obtain a warning message, informing that devices that joined this segment is sending a message.  If there are two devices that send at the same time, there will be a collision.

What the effect of the collision? Data are colliding not get to the destination. The devices must rearrange delivery schedules, and this takes time and causes the delivery process be delayed. So, all the devices connected to the hub will be on the same network segment, and also in same area or same domain, those device shared in the event of a collision because they are in same collision domain.

All hosts are connected to the hub are in the same physical network segment, it means that all the hosts that are connected to the hub are in the same collision domain.

If there is only one LAN hub, regardless of the number of hubs, on the LAN to form a collision domain, the more the number of hubs on the LAN, the greater the scope of the Collision Domain on the LAN.
To minimize the effect or influence of collision domains in the LAN, replace hubs with switches. Switch serves to break up a large scope collision domain into several collision domains smaller scope.
Switch serves to break up one large coverage collision domain into several smaller collision domains coverage.

In a switch, the collision domain is only formed at each port connected to a host or network device and effect only to port where host connected, not on the entire device.
On  switches are many collision domains, but the area coverage of the collision domain is small, only limited to the connection port. If there is a collision on one switch port, the collision effect does not affect on the overall switch.

The number of collision domains contained in the switch depends on the number of hosts or devices connected on switch port. If there are 10 hosts connected on each switch port, then it will create 10 Collision domain.

Broadcast Domain,  when hosts or network devices connected the hubs or switches, all hosts will be in the same network segment. If a host trying to communicate to another host in same network segment, that host will send a message to all device in same network segment,  an area that broadcasts sent is hear by all device or host is known as  a broadcast domain. A broadcast domain refers to the set of all devices on a network segment that hear all the broadcasts sent on that segment.

In a LAN that there were many hosts, causing crowded broadcast domain. The more crowded the broadcast message to be heard by the hosts, it will cause the flow of data becomes slow, each host is too busy to hear and process the broadcast messages they receive, the condition is known as a broadcast storm.
For the density of the number of hosts in a broadcast domain area should be reduced.
Break down a large broadcast domain coverage, can only be done by dividing a large LAN network segment, segment the network into several smaller LANs. Equipment and methods used is to use Routers and VLANs.
In a LAN that consists of a hub and a switch or brigde there is only one broadcast domain coverage.

Two LANs connected to each interface of the router or connect two deferent  VLAN on the switch,  so each of the LAN has an own broadcast domain.

Routers and VLANs running the same role as performed by the switch to Collision Domain.
Routers and VLANs divide a large broadcast domain coverage to be some smaller coverage broadcast domains.

For your convenience in learning CCNA, you have to understand the symbols of network devices.

Question  1
Which of the following statements describe the network shown in the graphic? (Choose two)

A. There are two broadcast domains in the network.
B. There are four broadcast domains in the network.
C. There are six broadcast domains in the network.
D. There are four collision domains in the network.
E. There are five collision domains in the network.
F. There are seven collision domains in the network.
Answer:  A, F
Discussion:  
On Sales LAN there is only hub. As I mentioned above that on hub there is only one broadcast and collision domains.

In Production LAN, there is a connection from a switch to a router and 5 pieces of hosts, As I explained above, that every connection on port switches have each collision domain. So on Production LAN, there are 6 connections on the port, so there are 6 Collision domain.

In Production LAN, there is onlyone broadcast domain.
Thus, the total broadcast domains on the overall network is 2 broadcast domains, each on Sales and ProductionLAN.

Domain Collision totals are sum of 1 Collision Domain on LAN Sales and Production6 Collision domainon the LAN, which is 7 Collision domain.
Question 2
How many collision domains and Broadcast domains are present in the diagram below?

A. There are two broadcast domains in the network.
B. There are three broadcast domains in the network.
C. There are four broadcast domains in the network.
D. There are eight collision domains in the network.
E. There are nine collision domains in the network.
F. There are ten collision domains in the network.

Answer:  B, E

Discussion:
The all-hub network at the bottom is one collision domain, and one broadcast domain.

On LAN above the router, there is one broadcast domain and three collision domains
Bridge just like switch,  every connection on port of bridges have each collision domain so in network above the router, that contain a Bridge and hub, should have 3 collision domains and one broadcast domain. The explanation about this, because there are 3 connection to the bridge. Collision domains contained in the hub is included in the third collision, because hubs were connected on same bridge.

On LAN left side the Router , 3 Switches that connecting each other. Two switch have connection to the a host, resulting 2 Collision domain. 2 Connection from switch to switch produce 2 collision domain. Last Switch that connect to router, have one collision domain on that port. Total number of collision domains on this LAN are 5. The broadcast domain only one for that LAN.
Total number of broadcast domains on the overall network are 3.
Total number of collision domains on the overall network are 9.