Which one of the following characteristics is true regarding the use of hubs and switches?

A. Hubs can have their ports be configured with VLANs

B. Using hubs is costly with regard to bandwidth availability.

C. Switches can not forward broadcasts.

D. Switches are more efficient than hubs in processing frames.

E. Switches increase the number of collision domains in the network.

Answer: E

Explanation:

 Switches increases the number of collisions domains in the network. Switches that are configured with VLANs will reduce the size of the collision domains by increasing the number of collision domains in a network, but making them smaller than that of one big, flat network.

QUESTION 2:

When comparing and contrasting the similarities and differences between bridges and switches, which of the following are valid statements? Choose all the valid answer choices)

A. Bridges are faster than switches because they have fewer ports.

B. A switch is a multiport bridge,

C. Bridges and switches learn MAC addresses by examining the source MAC address of each frame received.

D. A bridge will forward a broadcast but a switch will not.

E. Bridges and switches increase the size of a collision domain.

F. None of the above statements are true

Answer: B, C

Explanation: Both bridges and switches build the bridge table by listening to incoming frames and examining the source MAC address in the frame. Switches are multiport bridges that allow you to create multiple broadcast domains. Each broadcast domain is like a distinct virtual bridge within a switch

QUESTION 3:

Which of the following correctly describe the various functions and virtues of a router? (Select all valid answer choices)

A. Packet switching

B. Collision prevention on a LAN segment.

C. Packet filtering

D. Broadcast domain enlargement

E. Broadcast forwarding

F. Internetwork communication

G. None of the above

Answer: A, C, F

Explanation: The main function of a router is to connect different, separated networks together. In doing so, switching packets from one network to another is a primary function, along with providing for communication between networks. As an additional feature, routers are capable of providing filtering on a network address and application port level, so choice C is also correct.

QUESTION 4:

The LAN needs are expanding at the Certkiller corporate office, which is quickly growing. You are instructed to enlarge the area covered by a single LAN segment on the Certkiller network. Which of the following are layer 1 devices that you can use? (Choose all that apply.)

A. A switch

B. A router

C. A network adapter card

D. A hub

E. A repeater

Answer: D, E

Explanation: A hub simply repeats the electrical signal and makes no attempt to interpret the electrical signal (layer 1) as a LAN frame (Layer 2). So, a hub actually performs OSI layer 1 functions, repeating an electrical signal, whereas a switch performs OSI layer 2 functions, actually interpreting Ethernet header information, particularly addresses, to make forwarding decisions. Hubs can be used to increase the number of stations that can be supported on a LAN. Because the repeater does not interpret what the bits mean, but does examine and generate electrical signals, a repeater is considered to operate at Layer 1. Repeaters can be used to physically extend the LAN to greater distances.

QUESTION 5: Cisco is the leader in the router market space. What basic functions do their routers perform in a network? (Choose two)

A. The microsegmentation of broadcast domains

B. Path selection

C. Packet switching

D. Bridging between LAN segments

E. Access layer security

F. VLAN membership assignment

G. Application optimization

Answer: B, C

Explanation: The primary functions of a router are: Packet Switching and Path Selection. It is the routers job to determine the best method for delivering the data, and switching that data as quickly as possible.

QUESTION 6:

The Certkiller network administrator needs to determine what LAN devices to install on the Certkiller network. What are two advantages of using Layer 2 Ethernet switches over hubs? (Choose two)

A. Allowing simultaneous frame transmissions

B. Increasing the size of broadcast domains

 C. Increasing the maximum length of UTP cabling between devices

 D. Filtering frames based on MAC addresses

E. Decreasing the number of collision domains

Answer: A, D

Explanation: A: A half duplex connection is where only one device can send or receive at a time. A full duplex connection is where both devices can send and receive at the same time. Thus, if you have a 100Mb half-duplex connection, only sending at 100Mb OR receiving at 100Mb can happen at the same time. If you have a 100Mb full duplex connection, you can effectively get 200Mb out of the link because you could be sending 100Mb and receiving 100Mb at the same time. D: Switches are capable of filtering frames based on any Layer 2 fields. For example, a switch can be programmed to reject (not forward) all frames sourced from a particular network. Because link layer information often includes a reference to an upper-layer protocol, switches usually can filter on this parameter. Furthermore, filters can be helpful in dealing with unnecessary broadcast and multicast packets

Answer: B, D

Explanation:Cisco Discovery Protocol (CDP) is a proprietary protocol designed by Cisco to help administrators collect information about both locally attached and remote devices. By using CDP, you can gather hardware and protocol information about neighbor devices, which is useful info for troubleshooting and documenting the network. You can use: Show cdp neighbor Show cdp neighbor details Commands to gather the information of connected neighbors.

QUESTION 8:

CDP is running between two Certkiller devices. What information is supplied by CDP?

(Select three)

A. Device Identifiers

B. Capabilities list

C. Platform

D. Route identifier

 E. Neighbor traffic data

QUESTION 9:

Two Certkiller offices are connected as shown below:

A. Coaxial cable

B. Fiber optic cable

C. UTP cable

D. STP cable

E. None of the above

Answer: B

Explanation: 

Current Ethernet technology typically comes via either copper UTP or fiber cables. In this scenario the distance between the buildings is only 55 meters so either copper orfiber could be used, as the distance limitation for 100M UTP Ethernet is 100 meters. However, fiber would be a better fit as it is not prone to errors that could occur due to the voltage potential differences. Because fiber is a dielectric material, it's not susceptible to electrical interference. FO-product vendors also claim that fiber systems make secure communications easier. Interference immunity and lack of emissions are givens in FO

systems and in the fiber medium itself.

QUESTION 10:

Refer to the Certkiller network shown below:

[image] 

You work as a network technician at Certkiller .com. Please study the exhibit carefully. Based on the information shown above, what is needed to allow host Certkiller 1 to ping host Certkiller 2?

A. A crossover cable connecting the switches 

 B. A backbone switch connecting the switches with either fiber optic or straight-through cables

C. A straight-through cable connecting the switches

D. A CSU/DSU connected to the switches with straight-through cables

E. A router connected to the switches with straight-through cables

Answer: E

Explanation: 

Routers are Layers 3 devices used for inter-network communication. In this scenario there are two different networks, so both switches need to connect to a router using straight-through cables. A straight-through cable is used to connect two different devices like, switch to router,host to switch. Since we need to insert a router for communication between the two switches, straight through cables will be used between the switches and the router.

QUESTION 11:

[image]

Ethernet interfaces

B. A router with two Ethernet interfaces

C. A switch with one Ethernet and one serial interface

D. A router with one Ethernet A new Certkiller office is opening, and a network device needs to be installed in the place of the icon labeled Network Device to accommodate a leased line T1 to the Internet. Which network device and interface configuration meets the minimum requirements for this installation?

A. A switch with twoand one serial interface

 E. A router with one Ethernet and one modem interface F. None of the above

Answer: D

Explanation

Only a router can terminate a leased line T1 access circuit, and only a router can connecttwo different IP networks. Here, we will need a router with two interfaces, one serialconnection for the T1 and one Ethernet interface to connect to the switch on the LAN. 

QUESTION 12:

As a CCNA candidate, you must know the various layers of the OSI model. At which layers of the OSI Model do Wide Area Networks operate in? (Choose two)

A. Physical Layer

B. Datalink Layer

C. Network Layer

D. Session Layer

E. Transport Layer

F. Presentation Layer

G. Application Layer

Answer: A, B

Explanation: 

A WAN is a data communications network that covers a relatively broad geographic areaand that often uses transmission facilities provided by common carriers, such astelephone companies. WAN technologies generally function at the lower two layers ofthe OSI reference model: the physical layer and the data link layer as shown below.

[image] 

Note:

Occasionally WAN's would also be considered to operate at layer 3, but since thisquestion asked for only 2 choices layers 1 and 2 are better choices

QUESTION 13:

While troubleshooting a connectivity problem on the network, you issue the ping command from your PC command prompt, but the output shows "request times out." At which OSI layer is this problem associated with? 

A. The data link layer

B. The application layer

C. The access layer

D. The session layer

E. The network layer

Answer: E

Explanation: 

TCP/IP includes ICMP, a protocol designed to help manage and control the operation ofa TCP/IP network. The ICMP protocol provides a wide variety of information about anetwork's health and operational status. Control message is the most descriptive part of aname. ICMP helps control and manage IP's work and therefore is considered part ofTCP/IP's network layer.

QUESTION 15:

 A host computer has been correctly configured with a static IP address, but the default gateway is incorrectly set. Which layer of the OSI model will be first affected by this configuration error?

A. Layer 1

B. Layer 2

C. Layer 3

D. Layer 4

E. Layer 5

 F. Layer 6

 E. Layer 7

Answer: C

Explanation: 

IP Addressing and IP routing resides on the OSI Network layer, which is layer 3.

QUESTION 16:

Which layer of the OSI reference model is responsible for ensuring reliable end-to-end delivery of data?

A. Application

B. Presentation

 C. Session

 D. Transport

 E. Network

F. Data-Link

Answer: D

Explanation: 

A key function of the transport layer is to provide connection services for the protocolsand applications that run at the levels above it. These can be categorized as eitherconnection-oriented services or connectionless services. Some protocol suites, such as

TCP/IP, provide both a connection-oriented and a connectionless transport layerprotocol, to suit the needs of different applications.

The transport layer is also the place in the layer stack where functions are normallyincluded to add features to end-to-end data transport. Where network layer protocols arenormally concerned with just "best effort" communications, where delivery is notguaranteed. Transport layer protocols are given intelligence in the form of algorithms that

ensure that reliable and efficient communication between devices takes place. Thisencompasses several related jobs, including lost transmission detection and handling, andmanaging the rate at which data is sent to ensure that the receiving device is not overwhelmed.

Transmission quality, meaning ensuring that transmissions are received as sent, is soimportant that some networking references define the transport layer on the basis ofreliability and flow-control functions. However, not all transport layer protocols provide

these services. Just as a protocol suite may have a connection-oriented and aconnectionless transport layer protocol, it may also have one that provides reliability anddata management services, and one that does not. Again, this is the case with TCP/IP:there is one main transport layer protocol; TCP, that includes reliability and flow control

features, and a second, UDP, that doesn't.

Answer: E

Explanation: 

The Network layer (also called layer 3) manages device addressing, tracks the location of

devices on the network, and determines the best way to move data, which means that the

Network layer must transport traffic between devices that aren't locally attached. Routers

(layer 3 devices) are specified at the Network layer and provide the routing services

within an internetwork.

The Transport layer (Layer 4) defines several functions, including the choice of

protocols. The most important Layer 4 functions are error recovery and flow control. The

transport layer may provide for retransmission, i.e., error recovery, and may use flow

control to prevent unnecessary congestion by attempting to send data at a rate that the

network can accommodate, or it might not, depending on the choice of protocols.

Multiplexing of incoming data for different flows to applications on the same host is also

performed. Reordering of the incoming data stream when packets arrive out of order is

included. Examples include: TCP, UDP, and SPX.

Answer: E

Explanation: 

Only network address contains this information. To transmit the packets the sender uses

network address and datalink address. But the layer 2 address represents just the address

of the next hop device on the way to the sender. It is changed on each hop. Network

Answer: B, C

Explanation: 

The Transport Layer:

You can think of the transport layer of the OSI model as a boundary between the upper

and lower protocols. The transport layer provides a data transport service that shields the

upper layers from transport implementation issues such as the reliability of a connection.

The transport layer provides mechanisms for:

Segmenting upper layer application

The establishment, maintenance, and orderly termination of virtual circuits

information flow control and reliability via TCP

Transport fault detection and recovery 

The Network Layer:

Layer three of the OSI model is the network layer.

The network layer creates and sends packets from source network to destination 

network.

it provides consistent end-to-end packet delivery service and control information

it creates and uses layer3 addresses for use in path determination and to forward 

packets.

Incorrect Answers:

A: This correctly describes the physical layer, not the presentation layer.

D: Although the data link layer adds physical (MAC) source and destination addresses, it

adds it to a frame, not a segment.

E: Packets are encapsulated, not frames.

The Transport layer can provide reliable networking via acknowledgments, sequencing,

and flow control.

Acknowledgments Delivered segments are acknowledged to the sender. If they are not

acknowledged, the sender will retransmit.

* Sequencing Data segments are sequenced into their original order when they arrive at

the destination.

* Flow Control Provides buffer controls that prevent packet flooding to the destination

host. Buffers store bursts of data for processing when the transmission is complete.

Layer 4 protocols include the following:

* Transmission Control Protocol (TCP)

* User Datagram Protocol (UDP)

Sequenced Packet Exchange (SPX)A reliable communications protocol created by

Novell NetWare

Answer: C

Explanation: 

Flow control paces the transmission of data between a sending device and a receiving

device. Flow control ensures that the receiving device can absorb the data sent to it

before the sending device sends more. When the buffers on the receiving device are full,

a message is sent to the sending device to suspend transmission until the data in the

buffers has been processed.

Incorrect Answers:

A. Data retransmission mechanisms are not handled by control. They are most often

handled by transport layer protocols such as TCP.

B. This describes the reassembly portion of the segmentation and reassembly (SAR)

function of network equipment.

Answer: A, B, D 

QUESTION 24:

Part of the Certkiller network is displayed below:

[image] 

 Study the exhibit shown above. Host Certkiller A has established a connection with the Certkiller II server attached to interface E0 of the Certkiller 2 router. Which of the following statements describe the information contained in protocol data units sent from Host Certkiller to Certkiller II?

(Choose three)

A. The destination port number in a segment header will have a value of 80

B. The destination IP address of a packet will be the IP address of the E0 interface of the Certkiller 1 router

C. The destination IP address of a packet will be the IP address of the network interface of the Certkiller II server

D. The destination address of a frame will be the MAC address of the E0 interface of Certkiller 1 router

Answer: A, C, D

Answer: B

Explanation: 

HTTPS is the secured version of the HTTP application, which normally uses 128 bit SSL

encryption to secure the information sent and received on a web page. An example is a

banking web site, or a trustworthy shopping web site that takes credit card information. It

is an application layer protocol which uses TCP port 443.

Incorrect Answers

A. HTML is not a protocol.

C. TFTP uses UDP port 69.

D. Telnet uses TCP port 23.

E. SMTP uses TCP port 25.

Explanation: 

[image]

The exhibit above displays the partial contents of an encapsulation header.Which of the following are true of the network traffic represented in this diagram?

 (Select three) 

A. This is a UDP header

B. This is an OSI layer 4 header.

C. This is traffic from an FTP server.

D. This is traffic from an Telnet client.

E. The last PDU received in this session had a sequence number of 292735. 

Answer: B, C, E

 Explanation:  As the header contains the sequence number and ACK number fields, it represents a TCPheader. Choice B is correct as TCP works on Layer 4 i.e. Transport Layer.Source Port mentioned in the header is 21 which indicate it is FTP Traffic because FTP

uses port 20 and 21 for data and control. So choice C is correct.

QUESTION 30: 

 Acknowledgements, sequencing, and flow control are functions that are handled bywhich layer of the OSI model?  A. Layer 5

B. Layer 4

C. Layer 7

D. Layer 6

E. Layer 3

F. Layer 2

G. Layer 1

QUESTION 31: 

 A receiving host has failed to receive all of the segments that it should acknowledge.What can the host do to improve the reliability of this communication session? 

A. Start a new session using UDP

B. Obtain a new IP address from the DHCP server

C. Use a different source port for the session

D. Decrease the sequence number

E. Decrease the window size 

Answer: E 

Explanation:  A TCP window the amount of outstanding (unacknowledged by the recipient) data asender can send on a particular connection before it gets an acknowledgment back from the receiver that it has gotten some of it.For example if a pair of hosts are talking over a TCP connection that has a TCP windowsize of 64 KB (kilobytes), the sender can only send 64 KB of data and then it must stopand wait for an acknowledgment from the receiver that some or all of the data has beenreceived. If the receiver acknowledges that all the data has been received then the senderis free to send another 64 KB.One way to improve the reliability of the TCP connection is to reduce the window sizethat the receiver needs to receive before sending an acknowledgement. However, this willreduce throughput as more segments and acknowledgements will need to be sent in orderto transfer the same amount of data.

Answer: A Explanation: 

 The application layer is the highest layer (layer 7) of the OSI model, and is reserved forend user applications. Since FTP is itself an application, layer 7 is the highest layer used.Incorrect Answers:B, C, D, E, F, G. In any given FTP session, all of these layers will be used at some pointbut they are incorrect because the question asked for the highest layer used by FTP.

QUESTION 33:  

Which Layer 4 protocol is used for a Telnet connection between two Certkiller  routers?  

A. IP

B.ICMP

C. DNS

D.TCP

E. UDP 

 RTP

Answer:  D Explanation: 

 TCP is a reliable connection-oriented protocol. TCP uses acknowledgments, sequencing,and flow control to ensure reliability. Telnet uses TCP port 23.

QUESTION 34:

Answer: 

[image]

QUESTION 35:

Refer to the following exhibit

[image]

What data structure is described in the exhibit shown above?

  A. IP datagram

B. TCP segment

C. Ethernet frame

D. UDP datagram

E. FDDI frame

F. Token Ring frame

G. None of the above

Answer: B 

Explanation: 

The Figure below illustrates the fields and overall format of a TCP packet Twelve fields comprise a TCP packet.

Twelve fields comprise a TCP packet

[image]

Answer: C 

Explanation:  The following port numbers for the protocols listed above are as follows:FTP: TCP Port 20 and 21SMTP: TCP Port 25Telnet: TCP Port 23DNS: both TCP and UDP Port 53

true regarding ICMP packets?

 Answer: C, D 

Although TCP segments are similar to UDP segments, TCP packets contains some additional fields. Which of the following are found in a TCP header, but not in aUDP header?

Explanation:  The Figure below illustrates the fields and overall format of a TCP packet.Twelve fields comprise a TCP packet

[image]

2. Sequence Number-Usually specifies the number assigned to the first byte of data in thecurrent message. In the connection-establishment phase, this field also can be used todentify an initial sequence number to be used in an upcoming transmission.

3. Acknowledgment Number-Contains the sequence number of the next byte of data thesender of the packet expects to receive.4. Data Offset-Indicates the number of 32-bit words in the TCP header.5. Reserved-Remains reserved for future use.6. Flags-Carries a variety of control information, including the SYN and ACK bits usedfor connection establishment, and the FIN bit used for connection termination.7. Window-Specifies the size of the sender's receive window (that is, the buffer spaceavailable for incoming data).8. Checksum-Indicates whether the header was damaged in transit.9. Urgent Pointer-Points to the first urgent data byte in the packet.10. Options-Specifies various TCP options.11. Data-Contains upper-layer information.User Datagram Protocol (UDP)The User Datagram Protocol (UDP) is a connectionless transport-layer protocol (Layer 4)that belongs to the Internet protocol family. UDP is basically an interface between IP andupper-layer processes. UDP protocol ports distinguish multiple applications running on asingle device from one another.Unlike the TCP, UDP adds no reliability, flow-control, or error-recovery functions to IP.Because of UDP's simplicity, UDP headers contain fewer bytes and consume lessnetwork overhead than TCP.UDP is useful in situations where the reliability mechanisms of TCP are not necessary,such as in cases where a higher-layer protocol might provide error and flow control.UDP is the transport protocol for several well-known application-layer protocols,including Network File System (NFS), Simple Network Management Protocol (SNMP),Domain Name System (DNS), and Trivial File Transfer Protocol (TFTP).The UDP packet format contains four fields, as shown in the figure below. These includesource and destination ports, length, and checksum fields.A UDP packet consists of four fields.

[image]

QUESTION 39:   DRAG DROPYou work as a network administrator at Certkiller .com.Your boss, Mrs. Certkiller, is interested in the OSI layers. Match the items with the appropriate layers. Note that not all options are used. 

[image]

QUESTION 40:

Part of the Certkiller network is shown below:

[image]

The multi-segment configuration guidelines apply only to a single Ethernet "collision domain." A collision domain is formally defined as a single CSMA/CD network in whichthere will be a collision if two computers attached to the system transmit at the same time. An Ethernet system composed of a single segment or multiple segments linked withrepeaters is a network that functions as a single collision domain.