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CAU 1 :

A new network is being designed for your company , Acme , Inc

. if you use a class C IP network , which subnet mask will

provide one usable subnet per department while allowing

enough usable host addresses for each department specified in

the table

department

Number of users

corporate 7

custommer support 15

financial 13

HR 7

engineering 16

a. 255.255.255.192

b. 255.255.255.0

c. 255.255.255.224

d. 255.255.255.240

e. 255.255.255.248

CAU 2 :


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You need to describe the various types of flow-control to your

co-workers . which of the following are types of flow control

that can be used in a network ?

a. congestion avoidance

b. cut-through

c. buffering

d. load balacing

e. fragment-free

f. windowing

CAU 3 :

QUESTION 7

When a cable modem is being provisioned to

operate with a host system for Internetservices, which two options must occur beforeLayer 1 and 2 connectivity canoccur? (Choose two)

A. The cable modem must request an IP addressand core configuration information from

a Dynamic Host Configuration Protocol (DHCP)

server.B. The cable modem powering up must scan andlock on the RF data channel in thedownstream path.C. The modem must request a DOCSIS


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configuration file from a TFTP server.D. The cable modem must register with the CMTS.

E. The modem must read specific maintenance

messages in the downstream path.Answer: B, EExplanation:

According to the DOCSIS (Data-over-Cable ServiceInterface Specifications) when youfirst power up a cable modem it starts scanning

(starting at a low frequency) for a cable

signal. When ithears a cable modem stream itlistens for a broadcast (from the service

provider) which contains information (ie.frequency) needed to talk back with the headend. It then talks back and if it communicates theright authentication information, it is

allowed to proceed. Once these steps are

completed, layers 1 and 2 will be operational.QUESTION NO: 8

How is cable broadband technology able totransmit downstream and upstreamdata while at the same time delivering televisioncontent?

A. The cable operator uses the VHF hyperband to

transmit and receive data signals.B. The cable operator assigns any availablespectrum to data, depending on how its own

television spectrum is being used.C. The cable operator uses specific bandwidths for


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data signals specified by DOCSIS.D. The cable operator places its data signals into

clean areas where there is no

interference from noise or other signals.Answer: CQUESTION NO: 9

certifyme.comoperates a DSL network. What doesthe dsl operating-mode autocommand configure on a Cisco router?

A. It configures a Cisco router to automatically

detect the proper modulation method touse when connecting an ATM interface.B. It configures a Cisco router to automaticallydetect the proper DSL type (ADSL,

IDSL, HDSL, VDSL) to use when connecting anATM interface.C. It configures a Cisco router to automatically

detect the proper encapsulation method touse when connecting an ATM interface.D. It configures a Cisco router to automaticallydetect the proper authentication methodto use when connecting an ATM interface.E. None of the above

Answer: A

Explanation:dsloperating-mode auto interface configurationcommand to specify that the router

automatically detect the DSL modulation that theservice provider is using and set the


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DSL modulation to match. An incompatible DSLmodulation configuration can result in

failure to establish a DSL connection to the DSLAM

of the service providerExample:QUESTION 18:

A host computer has been correctly configured

with a static IP address, but the default gateway isincorrectly set. Which layer of the OSI model willbe first affected by this configuration error?

A. Layer 1B. Layer 2

C. Layer 3D. Layer 4E. Layer 5F. Layer 6

E. Layer 7Answer: C Explanation:IP Addressing and IP routing resides on the OSINetwork layer, which is layer 3.

QUESTION 19:

Which layer of the OSI reference model is

responsible for ensuring reliable end-to-end

delivery of data?

A. Application B. Presentation C. SessionD. TransportE. Network


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F. Data-LinkAnswer: D Explanation:

A key function of the transport layer is to provide

connection services for the protocols andapplications that run at the levels above it. Thesecan be categorized as either connection-oriented

services or connectionless services. Some protocolsuites, such as TCP/IP, provide both a connection-oriented and a connectionless transport layer

protocol, to suit the needs of different applications.

The transport layer is also the place in the layerstack where functions are normally included to add

features to end-to-end data transport. Wherenetwork layer protocols are normally concernedwith just best effort communications, wheredelivery is not

guaranteed. Transport layer protocols are given

intelligence in the form of algorithms thatensure that reliable and efficient communication

between devices takes place. This encompassesseveral related jobs, including lost transmissiondetection and handling, and managing the rate at

which data is sent to ensure that the receivingdevice is not

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overwhelmed.

Transmission quality, meaning ensuring thattransmissions are received as sent, is so important


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that some networking references define thetransport layer on the basis of reliability and flow-

control functions. However, not all transport layer

protocols provide these services. Just as a protocolsuite 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 doesnt.

QUESTION 20:

At which OSI layer is a logical path createdbetween two host systems named CK1and CK2 on the Certifyme LAN?

A. Physical B. Session C. Data link D. Transport E.NetworkF. ApplicationG. PresentationAnswer: E Explanation:

The Network layer (also called layer 3) managesdevice addressing, tracks the location of devices on

the network, and determines the best way to movedata, which means that the Network layer musttransport traffic between devices that arent locallyattached. Routers

(layer 3 devices) are specified at the Network layer


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and provide the routing services within aninternetwork.

QUESTION 21:

Which OSI layer is associated with the following:The acknowledgement of transmissions,sequencing, and flow control across a network?

A. Layer 2

B. Layer 3C. Layer 4

D. Layer 5E. Layer 6F. Layer 7

Answer: C

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Explanation:

The Transport layer (Layer 4) defines severalfunctions, including the choice ofprotocols. The most important Layer 4 functionsare error recovery and flow control. The transportlayer may provide for retransmission, i.e., errorrecovery, 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 ofprotocols. Multiplexing of incoming data fordifferent flows to applications on the same host is

also performed. Reordering of the incoming data


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stream when packets arrive out of order isincluded. Examples include: TCP, UDP, and SPX.

QUESTION 22:

Which OSI layer header contains the address of adestination host that is on another network?

A. Application B. Presentation C. SessionD. Transport E. Network F. Data link G. Physical

Answer: E Explanation:Only network address contains this information. To

transmit the packets the sender usesnetwork address and datalink address. But the

layer 2 address represents just the addressof the next hop device on the way to the sender. Itis changed on each hop. Network address remainsthe same.

QUESTION 23:

Which of the following correctly describe steps inthe OSI data encapsulation process? (Choose two)

A. The presentation layer translates bits intovoltages for transmission across the physical link.B. The transport layer divides a data stream into

segments and adds reliability and flow control

information.C. Packets are created when the network layeradds Layer 3 addresses and control information toa segment.

D. The data link layer adds physical source and


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destination addresses and an FCS to the segment.E. Packets are created when the network layer

encapsulates a frame with source and destination

host addresses and protocol-related controlinformation.

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Answer: B, C

Explanation:The Transport Layer:

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

and lower protocols. The transport layer provides adata transport service that shields the upper layersfrom transport implementation issues such as thereliability of a connection. The transport layer

provides mechanisms for:

Segmenting upper layer applicationThe establishment, maintenance, and orderlytermination of virtual circuits information flowcontrol and reliability via TCPTransport fault detection and recovery

The Network Layer:Layer three of the OSI model is the network layer.

The network layer creates and sends packets fromsource network to destination network.it provides consistent end-to-end packet deliveryservice and control information

it creates and uses layer3 addresses for use in


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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.

QUESTION 24:

When files are transferred between a host and anFTP server, the data is dividedinto smaller pieces for transmission. As these

pieces arrive at the destination host, they must bereassembled to reconstruct the original file. Whatprovides for the reassembly of these pieces intothe correct order?

A. The sequence number in the TCP headerB. The Start Frame Delimiter in the 802.3PreambleC. The TTL in the IP headerD. The acknowledgement number in the segment

headerE. The frame check sequence in the Ethernet frame

trailerAnswer: A Explanation:The Transport layer can provide reliablenetworking via acknowledgments, sequencing, and

flow control.


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Acknowledgments Delivered segments areacknowledged to the sender. If they are notacknowledged, the sender will retransmit.

QUESTION 26:

Refer to the following exhibit:

What data structure is described in the exhibitshown above? A. IP datagramB. TCP segment C. Ethernet frame D. UDPdatagram E. FDDI frameF. Token Ring frameG. None of the above

Answer: B

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

The following descriptions summarize the TCP

packet fields illustrated above.1. SourcePort and DestinationPort-Identifies points

at which upper-layer source and destinationprocesses receive TCP services.

2.3. Sequence Number-Usually specifies the numberassigned to the first byte of data in the current


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message. In the connection-establishment phase,this field also can be used to identify an initial

sequence number to be used in an upcoming

transmission.4.5. Acknowledgment Number-Contains the

sequence number of the next byte of data thesender of the packet expects to receive.6.

7. Data Offset-Indicates the number of 32-bit

words in the TCP header.8.

9. Reserved-Remains reserved for future use.10.11. Flags-Carries avariety of control information, including the SYN

and ACK bits used for connection establishment,

and the FIN bit used for connection termination.12.

13. Window-Specifies the size of the sendersreceive window (that is, the buffer space availablefor incoming data).

14.15. Checksum-Indicates whether the header was

damaged in transit.16.17. Urgent Pointer-Points to the first urgent databyte in the packet.18.


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19. Options-Specifies various TCP options. Data-Contains upper-layer information.

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QUESTION 27:

Network equipment supporting the use of flowcontrol mechanisms has beenrecently installed in the Certifyme network. What isthe purpose of flow control in a data network?

A. It ensures that data is retransmitted if an

acknowledgment is not received. B. It reassemblessegments in the correct order on the destinationdevice.C. It provides a mechanism for the receiver tocontrol the transmission speed. D. It regulates thesize of each datagram segment.E. All of the above are functions of flow control

Answer: C Explanation:Flow control paces the transmission of databetween a sending device and a receiving device.

Flow control ensures that the receiving device canabsorb the data sent to itbefore the sending device sends more. When the

buffers on the receiving device are full,

a message is sent to the sending device tosuspend transmission until the data in the buffershas been processed.Incorrect Answers:


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A. Data retransmission mechanisms are nothandled by control. They are most often handled

by transport layer protocols such as TCP.

B. This describes the reassembly portion of thesegmentation and reassembly (SAR)function of network equipment.

D. The maximum transmission unit (MTU) handlesthe regulation of maximum frame sizes.

QUESTION 28:

Part of the Certifyme network is displayed below:

Study the exhibit shown above. Host Certifyme A

has established a connection with the Certifyme IIserver attached to interface E0 of the Certifyme 2router. Which of the following statements describethe information contained in protocol data units

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sent from Host Certifyme to Certifyme II? (Choosethree)

A. The destination port number in a segmentheader will have a value of 80B. The destination IP address of a packet will be

the IP address of the E0 interface of the

Certifyme 1 routerC. The destination IP address of a packet will bethe IP address of the network interfaceof the Certifyme II server

D. The destination address of a frame will be the


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MAC address of the E0 interface ofCertifyme 1 router Answer: A, C, D QUESTION 29:

You have just installed a new web server on the

Certifyme network. You are requiredto ensure that the web server is accessible fromthe Internet. The network uses private addressing,

so an IP-to-registered address mapping isrequired.To do this, you enter the following command:

Certifyme (config)# ip nat inside source static

192.168.2.1198.18.1.254

You unsuccessfully try to ping the Internet from aPC host on the LAN. During the troubleshootingprocess, you enter the show ip nat translationscommand but the output is blank.What is the most likely cause of the problem?

A. The keyword overload is missing from thecommand. B. The NAT pool must be defined first.C. An access list must be defined to create staticNAT translations. D. The interfaces must beconfigured for NAT.E. None of the above

Answer: D Explanation:

In order to successfully configure a static NATtranslation, the interfaces must be configured forNAT, in addition to the global NAT command that

was entered. The router interface that lies on theinside part of the network must be defined using


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the ip nat inside command. Similarly, the WANinterface that is being used for the Internet

connection must be defined using the ip nat

outside command.Incorrect Answers:

A. In order to make an internal server reachablefrom the Internet, a static one to one NAT entry

must be configured for the server. The keywordoverload is used to configure many to one NAT,or PAT.

B, C. This need not be done in order to create astatic NAT entry. These steps are

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typically done in setting up NAT so that inside LANusers can access the Internet viaNAT.

QUESTION 30:Which protocol below uses TCP port 443 at layer4? A. HTML

B. HTTPSC. TFTP D. Telnet E. SMTPF. None of the above

Answer: B Explanation:

HTTPS is the secured version of the HTTPapplication, which normally uses 128 bit SSLencryption to secure the information sent and

received on a web page. An example is a bankingweb site, or a trustworthy shopping web site that


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takes credit card information. Itis an application layer protocol which uses TCP port

443.

Incorrect Answers:A. HTML is not a protocol. C. TFTP uses UDP port69. D. Telnet uses TCP port 23. E. SMTP uses TCPport 25.

QUESTION 31:

As a CCNA candidate, you will be expected to know

the OSI model very well.Which of the following are associated with the

application layer (layer 7) of the OSImodel? (Choose two)

A. TCP B. Telnet C. FTP D. Ping E. IPF. UDP Answer: B, CExplanation:

The application layer is the top layer of the OSImodel and is used to describe the end userapplications that can be used over a network.

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Layer Name Examples

Application (layer 7) Telnet, HTTP, FTP, WWW

browsers, NFS, SMTP gateways, SNMPIncorrect Answers:

A. TCP resides at layer 4.D. ARP is a function of the data link layer, which islayer 2. E. IP is used at layer 3 (network layer).


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Reference: CCNA Self-Study CCNA INTRO examcertification Guide (Cisco Press, ISBN 1-58720-094-5) Page 34.

QUESTION 32:

As the Certifyme network administrator, you arerequired to have a firm understanding of the OSI

model. Why does the data communication industryuse the layered OSI reference model? (Choosetwo)

A. It enables equipment from different vendors touse the same electronic components, thus saving

research and development fundsB. It encourages industry standardization bydefining what functions occur at each layerof the model

C. It divides the network communication process

into smaller and simpler components;thus aiding component development, design andtroubleshootingD. It provides a means by which changes infunctionality in one layer require changes in other

layersE. It supports the evolution of multiple competing

standards and thus provides business opportunitiesfor equipment manufacturersAnswer: B, C Explanation:The OSI (Open System Interconnection) reference

model was created as a reference point


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for communications devices. A layered approach isused to segment the entire telecommunications

process into a series of smaller steps.

A is correct because it encourages a level ofstandardization by encouraging thatfunctions be compared to known layers. D is also

correct because it allows engineers to focus on thedevelopment, refining, and perfection of simplercomponents.

QUESTION 33:

You need to describe the various types of flowcontrol to your co-workers. Which of the following

are types of flow control that can be used in anetwork? (Choose three)

A. Congestion avoidance

B. Windowing

C. Cut-through640-802

D. BufferingE. Load BalancingF. Fast Forward Answer: A, B, D QUESTION 34:

Which of the protocols below use TCP at the

transport layer? (Select four)A. TFTP B. SMTP C. SNMP D. FTPE. HTTP F. HTTPSAnswer: B, D, E, F Explanation:

SMTP (Simple Mail Transfer Profile for email), FTP


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(File Transfer Protocol), andHTTP/HTTPS (Hyper Text Transfer Protocol for

internet) all use TCP because of the reliable

delivery mechanism. SMTP uses TCP port 25, FTPuses TCP ports 20 and 21, HTTP uses TCP port 80,and HTTPS uses TCP port 443.

Incorrect Answers:A, C: SNMP and TFTP use UDP as the transportmechanism. Generally speaking, protocols that use

the keywords trivial or simple uses UDP, since

connectionless, best effort delivery mechanismusually suffice.

Reference: CCNA Self-Study CCNA INTRO examcertification Guide (Cisco Press,ISBN 1-58720-094-5) Page 163.

QUESTION 35:

Exhibit:The exhibit above displays the partial contents ofan encapsulation header.Which of the following are true of the networktraffic 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.

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

Answer: B, C, E Explanation:

As the header contains the sequence number andACK 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 whichindicate it is FTP Traffic because FTP

uses port 20 and 21 for data and control. So choice

C is correct.The acknowledgment number refers to the

sequence number of the last PDU received, whichis 292735, making choice E also correct.

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Bo 60 Cau Hoi Ccnet