CCNA 1 - Chapter 3 for Students

8/8/2019 CCNA 1 - Chapter 3 for Students

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2007 Cisco System s, Inc. All rights reserved. Cisco Public

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Chapter 1 1

Application Layer

Functionality andProtocols

Network Fundamentals Chapter 3


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Chapter 1 3Rainier Pimentel

T

wo basic types of networks

Peer-to-PeerNetworks

Client/Server

N

etworks


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P

eer-to-P

eer Networks In a peer-to-peer network, networked computers act asequal partners, or peers.

As peers, each computer can take on the client function or

the server function.

In a peer-to-peer network, individual users control their own

resources.

Since individual users make these decisions, there is nocentral point of control or administration in the network.


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Peer-to-Peer Networks

Peer-to-peer networks are relatively easy to install and

operate.

No additional equipment is necessary beyond a suitable

operating system installed on each computer.

Since users control their own resources, no dedicated

administrators are needed.

As networks grow, peer-to-peer relationships becomeincreasingly difficult to coordinate. A peer-to-peer network

works well with 10 or fewer computers.


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Peer to Peer

1. decentralizedresources

2. resource

sharingwithout adedicatedserver

3. Security is

difficult toenforce.

A computer that responds to a file sharing request is

functioning as a server.


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A small home network has been installed

to interconnect three computers togetherfor gaming and file sharing. What twoproperties represent this network type?(Choose two.)

a. User accounts are centralized.

b. Security is difficult to enforce.

c. Specialized operating system software is required.

d. File permissions are controlled by a single computer.

e. A computer that responds to a file sharing request isfunctioning as a server.


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A small home network has been installed

to interconnect three computers togetherfor gaming and file sharing. What twoproperties represent this network type?(Choose two.)

a. User accounts are centralized.

b. Security is difficult to enforce.

c. Specialized operating system software is required.

d. File permissions are controlled by a single computer.

e. A computer that responds to a file sharing request isfunctioning as a server.


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What are two characteristics of peer-to-peer networks? (Choose two.)

a. scalable

b. one way data flow

c. decentralized resources

d. centralized user accounts

e. resource sharing without a dedicated server


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What are two characteristics of peer-to-peer networks? (Choose two.)

a. scalable

b. one way data flow

c. decentralized resources

d. centralized user accounts

e. resource sharing without a dedicated server


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Peer to Peer

Some P2P applications use a hybrid systemwhere resource sharing is decentralized but the

indexes that point to resource locations arestored in a centralized directory.

Peer-to-peer applications can be used on peer-to-peer networks, client/server networks, and

across the Internet.


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What are three properties of peer-to-peerapplications? (Choose three.)

a. acts as both a client and server within the samecommunication

b. requires centralized account administrationc. hybrid mode includes a centralized directory of files

d. can be used in client-server networks

e. requires a direct physical connection between devices

f. centralized authentication is required


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What are three properties of peer-to-peerapplications? (Choose three.)

a. acts as both a client and server within the samecommunication

b. requires centralized account administrationc. hybrid mode includes a centralized directory of files

d. can be used in client-server networks

e. requires a direct physical connection between devices

f. centralized authentication is required


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Client/Server Networks


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Client/Server Network

Some nodes (SERVER) are dedicated to presentservices to other nodes (CLIENTS)

Client1

Client2 Server

Client3

centralized administration security is easier to

enforce


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Client/Server Network

centralized user accounts

Client computers initiate dataexchanges and may upload data

to servers


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Client/Server Networks

In a client/server arrangement, network services are

located on a dedicated computer called a server.

The server responds to the requests of clients.

The server is a central computer that is continuously

available to respond to requests from clients for file, print,

application, and other services.

Servers are designed to handle requests from many clientssimultaneously.


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What are two characteristics of clients in

data networks? (Choose two.)

1. initiate data exchanges

2. are repositories of data

3. may upload data to servers

4. listen for requests from servers


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What are two characteristics of clients in

data networks? (Choose two.)

1. initiate data exchanges

2. are repositories of data

3. may upload data to servers

4. listen for requests from servers


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A network administrator is designing anetwork for a new branch office of twenty-fiveusers. What are the advantages of using aclient-server model? (Choose two.)

a. centralized administration

b. does not require specialized software

c. security is easier to enforce

d. lower cost implementation


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A network administrator is designing anetwork for a new branch office of twenty-fiveusers. What are the advantages of using aclient-server model? (Choose two.)

a. centralized administration

b. does not require specialized software

c. security is easier to enforce

d. lower cost implementation


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Applications The Interface BetweenHuman and Data Networks

Applications provide the means for generating and

receiving data that can be transported on the network


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Application layer (definitions)

Application layer supplies services that allow user tointerface with the network.

It provides the interface between the applications oneither end of the network

Application layer provides services for an applicationprogram to ensure that effective communication withanother application program in a network.


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Which layer of the OSI model suppliesservices that allow user to interface with the

network?

a. physical

b. session

c. network

d. presentation

e. application

f. transport


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Which layer of the OSI model suppliesservices that allow user to interface with the

network?

a. physical

b. session

c. network

d. presentation

e. application

f. transport


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What is the role of the OSI applicationlayer?

a. provides segmentation of data

b. provides encryption and conversion of data

c. provides the interface between the applications oneither end of the network

d. provides control of all the data flowing between thesource and destination devices


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What is the role of the OSI applicationlayer?

a. provides segmentation of data

b. provides encryption and conversion of data

c. provides the interface between the applications oneither end of the network

d. provides control of all the data flowing between thesource and destination devices


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2 Forms ofApplication

Layer Software

Applications

Web browsers, Email program

Services

Application Protocols(FTP, HTTP, DNS, Telnet, DHCP)


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What are two forms of application layersoftware? (Choose two.)

a. applications

b. dialogs

c. requests

d. services

e. spreadsheet


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What are two forms of application layersoftware? (Choose two.)

a. applications

b. dialogs

c. requests

d. services

e. spreadsheet


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Application LayerProtocols

FTP and TFTP

File TransferProtocol (FTP)

FTP enables file sharing between hosts.

FTP is commonly used to support for filetransfers between a client and a server

Trivial File TransferProtocol (TFTP)

TFTP is a connectionless service that uses theUserDatagram Protocol (UDP).


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What application layer protocol is commonly used tosupport for file transfers between a client and a

server?

a. DNS

b. HTTP

c. FTP

d. Telnet


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What application layer protocol is commonly used tosupport for file transfers between a client and a

server?

a. DNS

b. HTTP

c. FTP

d. Telnet


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Server Message Block (SMB) is an applicationlayer protocol that describes the services that areused for file sharing in Microsoft networks

Network File System (NFS)NFS is a

distributed file system protocol suite developed bySun Microsystems that allows file access to aremote storage device such as a hard disk across

a network.


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What application layer protocol describes theservices that are used for file sharing in

Microsoft networks?

a. DHCP

b. DNS

c. SMB

d. SMTP

e. WINS


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What application layer protocol describes theservices that are used for file sharing in

Microsoft networks?

a. DHCP

b. DNS

c. SMB

d. SMTP

e. WINS


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Simple Mail TransferProtocol (SMTP) SMTPadministers the transmission of e-mail overcomputer networks.

It is used to forward mail between servers.

It is a protocol that operates at the Applicationlayer of the OSI model


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(Telnet and SSH) Terminal emulation (Telnet) Telnet provides the

capability to remotely access another computer.

Secure Shell (SSH), a common network protocol forremote administration of Unix computers.

Telnet does not support encryption


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Telnet protocol

Telnetprovides a

virtualconnection forremote access


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Which application layer protocols correctlymatch a corresponding function? (Choose

two.)

a. DNS dynamically allocates IP addresses to hosts

b. HTTP transfers data from a web server to a client

c. POP delivers email from the client to the server emailserver

d. SMTP supports file sharing

e. Telnet provides a virtual connection for remote access


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Which application layer protocols correctlymatch a corresponding function? (Choose

two.)

a. DNS dynamically allocates IP addresses to hosts

b. HTTP transfers data from a web server to a client

c. POP delivers email from the client to the server emailserver

d. SMTP supports file sharing

e. Telnet provides a virtual connection for remote access


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As compared to SSH, what is the primarydisadvantage of telnet?

a. not widely available

b. does not support encryption

c. consumes more network bandwidth

d. does not support authentication


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As compared to SSH, what is the primarydisadvantage of telnet?

a. not widely available

b. does not support encryption

c. consumes more network bandwidth

d. does not support authentication


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Simple Network Management Protocol (SNMP)SNMP is a protocol that provides a way to monitorand control network devices, and to manageconfigurations, statistics collection, performance,and security.


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HTTP and HTTPS HTTP - defines the rules for transferring information,

files, and multimedia on web pages. Hypertext MarkupLanguage (HTML) is the language used within HTTP.

HTTPS is the secured version of the HTTP application,which normally uses 128 bit SSL encryption to securethe information sent and received on a web page.

These two protocols are used tocontrol the transfer of web

resources from a web server toa client browser.


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Which two protocols are used to control thetransfer of web resources from a web server to

a client browser? (Choose two.)

a. ASP

b. FTP

c. HTML

d. HTTP

e. HTTPS


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Which two protocols are used to control thetransfer of web resources from a web server to

a client browser? (Choose two.)

a. ASP

b. FTP

c. HTML

d. HTTP

e. HTTPS


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DHCP

The Dynamic Host Configuration Protocol (DHCP)service enables devices on a network to obtain IPaddresses and other information from a DHCP server.

DHCP allows a host to obtain an IP addressdynamically when it connects to the network. TheDHCP server is contacted and an address requested.The DHCP server chooses an address from a

configured range of addresses called a pool andassigns ("leases") it to the host for a set period.


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DHCP


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DHCP

TheD

HCP leasing process


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What is DNS?

It is a database system that translates hostname to IPaddresses

It is a protocol that operates at the Application layer ofthe OSI model

It is used by the server to resolve names

It is the automated service that matches resource

names with the required IP address


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DNS


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DNS (Common Resource Records)

Record Type Use

A (host address)

The A record maps a DNS host name to an IP

address. This is the most common resource

record type.

CNAME (canonicalname)

The CNAME record provides alternate names

(or aliases) to hosts that already have an A

record.

MX (Mail Exchanger)The MX record identifies servers that can be

used to deliver mail.

NS (name server)

The NS resource record identifies all name

servers that can perform name resolution for thezone.

PTR (pointer)

In a reverse lookup zone, the PTR record maps

an IP address to a host name (i.e. "points" to an

A record).


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Email Services and POP3/SMTP

Protocols POP3 (Post Office Protocol version 3) allows your

computer to receive emails and SMTP means it cansend emails.

POP3 allows users to pickup email across the network.

SMTP (Simple Mail Transfer Protocol) delivers emailacross the network.

email components are used to forward mail betweenservers.


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MUA (Mail UserAgent)

MUA is also called e-mail client

MUA is the program that the user used to create emailmessages.

To receive e-mail messages from an e-mail server, thee-mail client can use POP. Sending e-mail from either aclient or a server uses message formats and commandstrings defined by the SMTP protocol.

MTA (Mail TransferAgent) receives email from theclient's MUA


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MDA (Mail Delivery Agent)

A MDA is software that delivers e-mail messages rightafter they've been accepted on a server.

MTA passes email to the MDA for final delivery.


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MTA (Mail TransferAgent )

The Mail Transfer Agent (MTA) process is used toforward e-mail.

The MTA receives messages from the MUA or fromanother MTA on another e-mail server.

Based on the message header, it determines how amessage has to be forwarded to reach its destination. Ifthe mail is addressed to a user whose mailbox is on the

local server, the mail is passed to the MDA. If the mailis for a user not on the local server, the MTA routes thee-mail to the MTA on the appropriate server.


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MTA

MTA passes email to the MDA for final delivery.

MTA uses SMTP to route email between servers.

MTA receives email from the client's MUA.


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Email Services (SMTP and POP)

MTA and SMTP areemail components areused to forward mail

between servers


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Email Services (SMTP and POP)

1. MTA receives email

from the client's MUA2. MTA passes email to

the MDA for finaldelivery

3. MTA uses SMTP toroute email between

servers


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The process of sending mails

between clients

1. MUA

2. SMTP3. MTA4. SMTP5. MTA6. MDA

7. POP8. MUA


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Which email components are used to forwardmail between servers? (Choose two.)

a. MDA

b. IMAP

c. MTA

d. POP

e. SMTP


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Which email components are used to forwardmail between servers? (Choose two.)

a. MDA

b. IMAP

c. MTA

d. POP

e. SMTP


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Which statements are correct concerning therole of the MTA in handling email? (Choosethree.)

a. routes email to the MDA on other servers

b. receives email from the client's MUA

c. receives email via the POP3 protocol

d. passes email to the MDA for final delivery

e. uses SMTP to route email between servers


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Which statements are correct concerning therole of the MTA in handling email? (Choosethree.)

a. routes email to the MDA on other servers

b. receives email from the client's MUA

c. receives email via the POP3 protocol

d. passes email to the MDA for final delivery

e. uses SMTP to route email between servers


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Presentation Layer

Presents data to the Application Layer

Provides data translation, coding, and conversion functions

Translates genericallyformatted data into its native format

(EBCDIC to ASCII)

Data compression, decompression, encryption, anddecryption

Ex: PICT/TIFF/JPEG/MIDI/MPEG/QuickTime


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Port Numbers

Application layer uses support from lower layer functionsto distinguish between connections to the service


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What is the destination port for thecommunication that is represented on line 82?

a. 80

b. 1261

c. 15533

d. 3912

e. 65520


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What is the destination port for thecommunication that is represented on line 82?

a. 80

b. 1261

c. 15533

d. 3912

e. 65520


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How does the application layer on a

server usually process multiple clientrequest for services?

a. ceases all connections to the service

b. denies multiple connections to a single daemon

c. suspends the current connection to allow the newconnection

d. uses support from lower layer functions to distinguish

between connections to the service


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How does the application layer on a

server usually process multiple clientrequest for services?

a. ceases all connections to the service

b. denies multiple connections to a single daemon

c. suspends the current connection to allow the newconnection

d. uses support from lower layer functions to distinguish

between connections to the service


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CCNA 1 - Chapter 3 for Students

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