CCNA 640-802 Exam

QUESTION 1:
Which of the following devices can an administrator use to segment their LAN?
(Choose all that apply)
A. Hubs
B. Repeaters
C. Switches
D. Bridges
E. Routers
F. Media Converters
G. All of the above

Explanation:
Switches and bridges forward broadcast but routers do not forward broadcasts by default (they can via the "ip helper-address" command).
Switches, bridges and routers can segment an Ethernet collision domain via the use of
VLAN's
Incorrect Answers:
A. Hubs is incorrect because a hub doesn't segment a network, it only allows more hosts on one. Hubs operate at layer one, and is used primarily to physically add more stations to the LAN.
B. This also incorrect because the job of a repeater is to repeat a signal so it can exceed distance limitations. It also operates at layer one and provides no means for logical LAN segmentation.
F. This is incorrect because media converters work by converting data from a different media type to work with the media of a LAN. It also operates at layer one and provides no means for logical LAN segmentation.

QUESTION 2:
Routers perform which of the following functions? (Select Three)
A. Packet switching
B. Collision prevention on a LAN segment.
C. Packet filtering
D. Broadcast domain enlargement
E. Broadcast forwarding
F. Internetwork communication

Explanation:
A. Routers work in Layer 3 of the OSI Model. A major function of the router is to route packets between networks.
C. Through the use of access lists, routers can permit and deny traffic using layer 3 and layer 4 packet information.
F. The primary purpose of a router is to route traffic between different networks, allowing for internetworking.
Incorrect Answers:
B. While routers can be used to segment LANs, which will reduce the amount of collisions; it can not prevent all collisions from occurring. As long as there are 2 or more devices on a LAN segment, the possibility of a collision exists, whether a router is used or not.
D. The broadcast domain of a LAN is often segmented through the use of a router. This results in reducing the size of the broadcast domain.
E. Routers do not forward broadcast traffic.

QUESTION 3:
Within the Certkiller office, The Sales and Production networks are separated by a router as shown in the diagram below:

Which of the following statements most accurately describes the characteristics of the above networks broadcast and collision domains? (Select the two best answer choices)
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.

Explanation:
In this network we have a hub being used in the Sales department, and a switch being used in the Production department. Based on this, we have two broadcast domains: one for each network being separated by a router. For the collision domains, we have 5 computers and one port for E1 so we have 6 collision domains total because we use a switch in the Production Department so 5 are created there, plus one collision domain for the entire Sales department because a hub is being used.

QUESTION 4:
The Certkiller corporate LAN consists of one large flat network. You decide to segment this LAN into two separate networks with a router. What will be the affect of this change?
A. The number of broadcast domains will be decreased.
B. It will make the broadcasting of traffic between domains more efficient between segments.
C. It will increase the number of collisions.
D. It will prevent segment 1's broadcasts from getting to segment 2.
E. It will connect segment 1's broadcasts to segment 2.

Explanation
A router does not forward broadcast traffic. It therefore breaks up a broadcast domain, reducing unnecessary network traffic. Broadcasts from one segment will not be seen on the other segment.
Incorrect Answers:
A. This will actually increase the number of broadcast domains from one to two.
B. All link level traffic from segment one to segment two will now need to be routed between the two interfaces of the router. Although this will reduce the traffic on the LAN links, it does also provide a less efficient transport between the segments.
C. Since the network size is effectively cut into half, the number of collisions should decrease dramatically.
E. Broadcasts from one segment will be completely hidden from the other segment.

QUESTION 5:
Which of the following are benefits of segmenting a network with a router? (Select all that apply)
A. Broadcasts are not forwarded across the router.
B. All broadcasts are completely eliminated.
C. Adding a router to the network decreases latency.
D. Filtering can occur based on Layer 3 information.
E. Routers are more efficient than switches and will process the data more quickly.
F. None of the above.

Explanation
Routers do not forward broadcast messages and therefore breaks up a broadcast domain.
In addition, routers can be used to filter network information with the use of access lists.
Incorrect Answers:
B. Broadcasts will still be present on the LAN segments. They will be reduced, because routers will block broadcasts from one network to the other.
C. Adding routers, or hops, to any network will actually increase the latency.
E. The switching process is faster than the routing process. Since routers must do a layer 3 destination based lookup in order to reach destinations, they will process data more slowly than switches.

QUESTION 6:

A. 192.168.5.5
B. 192.168.5.32
C. 192.168.5.40
D. 192.168.5.63
E. 192.168.5.75

Explanation:
The subnet mask used on this Ethernet segment is /27, which translates to 255.255.255.224. Valid hosts on the 192.168.5.33/27 subnet are 192.168.5.33-192.168.5.62, with 192.168.5.32 used as the network IP address and 192.168.5.63 used as the broadcast IP address. Therefore, only choice C falls within the usable IP range.

QUESTION 7:
The Certkiller .com network is displayed in the diagram below:

A. One
B. Two
C. Three
D. Four
E. Five
F. Six
G. Fourteen

Explanation:
Since hubs are being used for both Ethernet segments, there are a total of two collision domains. Routers do not forward broadcast and are used to segment LANs, so Certkiller A consists of one collision domain while Certkiller B consists of the second collision domain.

QUESTION 8:
The Certkiller network is displayed in the following diagram:

Based on the diagram shown above, which of the devices shown can transmit simultaneously without causing collisions?
A. All hosts
B. Only hosts attached to the switch
C. All hosts attached to the hub and one host attached to the switch
D. All hosts attached to the switch and one host attached to the hub

Explanation:
Unlike hubs, a switch is the device which is used to avoid collisions. When two computers communicate through a switch they make their own collision domain. So, there is no chance of collisions. Whenever a hub is included, it supports on half duplex communication and works via CSMA/CD technology, so there is always a chance of collision. In fact, some collisions are a normal occurrence in CSMA/CD.

QUESTION 9:
The Certkiller network is displayed in the diagram below:

A. All the devices in both networks will receive a broadcast to 255.255.255.255 sent by host Certkiller A.
B. Only the devices in network 192.168.1.0 will receive a broadcast to 255.255.255.255 sent by host Certkiller A.
C. All the devices on both networks are members of the same collision domain.
D. The hosts on the 192.168.1.0 network form one collision domain, and the hosts on the 192.168.2.0 network form a second collision domain.
E. Each host is in a separate collision domain.

Explanation:
Since the devices shown in the diagram are switches, B is in fact correct. D is not correct.
If the diagram used hubs and not switches then yes, there would only be two collision domains, but the diagram has switches. The author may have intended to state broadcast domains which would have been correct as well.
Answer E is also correct, since the network is comprised of switches each host will be in a separate collision domain.

QUESTION 10:
Given the choices below, which address represents a unicast address?
A. 224.1.5.2
B. FFFF. FFFF. FFFF.
C. 192.168.24.59/30
D. 255.255.255.255
E. 172.31.128.255/18

Explanation:
172.31.128.255 is the only unicast address. It seems to be a broadcast address, because of
255 in the last octet. However, the broadcast address for this network is actually
172.31.131.255.
Incorrect Answers:
A: 224.1.5.2 is a multicast address.
B: This is a broadcast layer 2 (data link) address.
C: Using a /30 for the subnet mask, this IP address becomes the broadcast address.
D. This is a broadcast IP address.