Ensurepass

Interconnecting Cisco Networking Devices Part 1 v3.0 (ICND1)

 

QUESTION 21

Which three statements are true about the operation of a full-duplex Ethernet network? (Choose three.)

 

A.

There are no collisions in full-duplex mode.

B.

A dedicated switch port is required for each full-duplex node.

C.

Ethernet hub ports are preconfigured for full-duplex mode.

D.

In a full-duplex environment, the host network card must check for the availability of the network media before transmitting.

E.

The host network card and the switch port must be capable of operating in full-duplex mode.

 

Correct An
swer:
ABE

Explanation:

Half-duplex Ethernet is defined in the original 802.3 Ethernet and Cisco says you only use one wire pair with a digital signal running in both directions on the wire. It also uses the CSMA/CD protocol to help prevent collisions and to permit retransmitting if a collision does occur. If a hub is attached to a switch, it must operate in half-duplex mode because the end stations must be able to detect collisions. Half-duplex Ethernet–typically 10BaseT–is only about 30 to 40 percent efficient as Cisco sees it, because a large 10BaseT network will usually only give you 3- to 4Mbps–at most.

Full-duplex Ethernet uses two pairs of wires, instead of one wire pair like half duplex. Also, full duplex uses a point-to-point connection between the transmitter of the transmitting device and the receiver of the receiving device, which means that with full-duplex data transfer, you get a faster data transfer compared to half duplex. And because the transmitted data is sent on a different set of wires than the received data, no collisions occur. The reason you don’t need to worry about collisions is because now Full-duplex Ethernet is like a freeway with multiple lanes instead of the single-lane road provided by half duplex. Full-duplex Ethernet is supposed to offer 100 percent efficiency in both directions; this means you can get 20Mbps with a 10Mbps Ethernet running full duplex, or 200Mbps for FastEthernet.

 

 

QUESTION 22

Refer to the exhibit. A network has been planned as shown. Which three statements accurately describe the areas and devices in the network plan? (Choose three.)

 

clip_image002

 

A.

Network Device A is a switch.

B.

Network Device B is a switch.

C.

Network Device A is a hub.

D.

Network Device B is a hub.

E.

Area 1 contains a Layer 2 device.

F.

Area 2 contains a Layer 2 device.

 

Correct Answer: ADE

Explanation:

Switches use a separate collision domain for each port, so device A must be a switch. Hubs, however, place all ports in the same collision domain so device B is a hub. Switches reside in layer 2 while hubs are layer 1 devices.

 

 

QUESTION 23

A workstation has just resolved a browser URL to the IP address of a server. What protocol will the workstation now use to determine the destination MAC address to be placed into frames directed toward the server?

 

A.

HTTP

B.

DNS

C.

DHCP

D.

RARP

E.

ARP

 

Correct Answer: E

Explanation:

The RARP protocol is used to translate hardware interface addresses to protocol addresses. The RARP message format is very similar to the ARP format. When the booting computer sends the broadcast ARP request, it places its own hardware address in both the sending and receiving fields in the encapsulated ARP data packet. The RARP server will fill in the correct sending and receiving IP addresses in its response to the message. This way the booting computer will know its IP address when it gets the message from the RARP server.

 

 

QUESTION 24

How does a switch differ from a hub?

 

A.

A switch does not induce any latency into the frame transfer time.

B.

A switch tracks MAC addresses of directly-connected devices.

C.

A switch operates at a lower, more efficient layer of the OSI model.

D.

A switch decreases the number of broadcast domains.

E.

A switch decreases the number of collision domains.

 

Correct Answer: B

Explanation:

Some of the features and functions of a switch include:

A switch is essentially a fast, multi-port bridge, which can contain dozens of ports. Rather than creating two collision domains, each port creates its own collision domain. In a network of twenty nodes, twenty collision domains exist if each node is plugged into its own switch port.

If an uplink port is included, one switch creates twenty-one single-node collision domains. A switch dynamically builds and maintains a Content-Addressable Memory (CAM) table, holding all of the necessary MAC information for each port.

For a detailed description of how switches operate, and their key differences to hubs, see the reference link below.

Reference: http://www.cisco.com/warp/public/473/lan-switch-cisco.shtml

QUESTION 25

Refer to the exhibit. If the hubs in the graphic were replaced by switches, what would be virtually eliminated?

 

clip_image004

 

A.

broadcast domains

B.

repeater domains

C.

Ethernet collisions

D.

signal amplification

E.

Ethernet broadcasts

 

Correct Answer: C

Explanation:

Modern wired networks use a network switch to eliminate collisions. By connecting each device directly to a port on the switch, either each port on a switch becomes its own collision domain (in the case of half duplex links) or the possibility of collisions is eliminated entirely in the case of full duplex links.

 

 

QUESTION 26

What are two common TCP applications? (Choose two.)

 

A.

TFTP

B.

SMTP

C.

SNMP

D.

FTP

E.

DNS

 

Correct Answer: BD

Explanation:

SMTP uses TCP port 25, while FTP uses TCP ports 20 and 21.

Reference: http://pentestlab.wordpress.com/2012/03/05/common-tcpip-ports/

 

QUESTION 27

DRAG DROP

On the left are various network protocols. On the right are the layers of the TCP/IP model. Assuming a reliable connection is required, move the protocols on the left to the TCP/IP layers on the right to show the proper encapsulation for an email message sent by a host on a LAN. (Not all options are used.)

 

clip_image006

 

Correct Answer:

clip_image008

 

 

QUESTION 28

What must occur before a workstation can exchange HTTP packets with a web server?

 

A.

A UDP connection must be established between the workstation and its default gateway.

B.

A UDP connection must be established between the workstation and the web server.

C.

A TCP connection must be established between the workstation and its default gateway.

D.

A TCP connection must be established between the workstation and the web server.

E.

An ICMP connection must be established between the workstation and its default gateway.

F.

An ICMP connection must be established between the workstation and the web server.

 

Correct Answer: D

Explanation:

HTTP uses TCP port 80, and a TCP port 80 connection must be established for HTTP communication to occur.

http://pentestlab.wordpress.com/2012/03/05/common-tcpip-ports/

 

QUESTION 29

Refer to the exhibit. SwitchA receives the frame with the addressing shown. According to the command output also shown in the exhibit, how will SwitchA handle this frame?

 

clip_image010

 

A.

It will drop the frame.

B.

It will forward the frame out port Fa0/6 only.

C.

It will flood the frame out all ports.

D.

It will flood the frame out all ports except Fa0/3.

 

Correct Answer: B

Explanation:

Switches keep the learned MAC addresses in a table, so that when a frame comes in with a destination MAC address that the switch has already learned, it will forward it to that port only. If a frame comes in with a destination MAC that is not already in the MAC address table, then the frame will be flooded to all ports except for the one that it came in on. In this case, Switch A already knows that 00b0.d0da.cb56 resides on port fa0/6, so it will forward the from out that port.

 

 

QUESTION 30

A network administrator is connecting PC hosts A and B directly through their Ethernet interfaces as shown in the graphic. Ping attempts between the hosts are unsuccessful. What can be done to provide connectivity between the hosts? (Choose two.)

 

clip_image012

 

A.

A crossover cable should be used in place of the straight-through cable.

B.

A rollover cable should be used in place of the straight-through cable.

C.

The subnet masks should be set to 255.255.255.192

D.

A default gateway needs to be set on each host.

E.

The hosts must be reconfigured to use private IP addresses for direct connections of this type.

F.

The subnet masks should be set to 255.255.255.0

 

Correct Answer: AF

Explanation:

If you need to connect two computers but you don’t have access to a network and can’t set up an ad hoc network, you can use an Ethernet crossover cable to create a direct cable connection.

Generally speaking, a crossover cable is constructed by reversing (or crossing over) the order of the wires inside so that it can connect two computers directly. A crossover cable looks almost exactly like a regular Ethernet cable (a straight-through cable), so make sure you have a crossover cable before following these steps.

Both devices need to be on the same subnet, and since one PC is using 192.1.1.20 and the other is using 192.1.1.201, the subnet mask should be changed to 255.255.255.0.

 

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