2 the Open Systems Interconnection (Osi) Model and Network Protocols

8/19/2019 2 the Open Systems Interconnection (Osi) Model and Network Protocols

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2. THE OPEN SYSTEMSINTERCONNECTION (OSI) MODEL

AND NETWORK PROTOCOLS.

2.1 Know Network Communications

2.2 Understand a Local Wired Network

2.3 Understand basic concept of internet connection and information sent

across internet2.4 Understand Network Serices

2.! "ppl# email client serer

2.$ "ppl# "ddressin% Sc&emes for 'C()*( suite


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2.1.1 DESCRIBE THE PURPOSE OF THEOSI MODEL AND EACH OF ITS LAYERS.


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2.1.1 +escribe t&e purpose of t&e,S* -odel and of eac& of its la#ers.

• ,S* model is used

– to describe w&at tasks a protocol suite

performs as we e/plore &ow data moes acrossa network.

• " protoco !"#t$ is most easil# de0ned – as a set of rules used to determine &ow

computers communicate wit& eac& ot&er.

3


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,pen S#stem*nterconnection ,S*

• ,pen S#stem *nterconnection ,S* merupakan sebua&

model untuk komunikasi komputer #an% terdiri dari

la#er atau lapisan ,S* la#er.

• Sebelum adan#a ,S* #an% merupakan standard

antaraban%sa ini setiap s#arikat komputer seperti *5-

dan +6C mempun#ai seni bina masin%7masin% se&in%%a

produk #an% di&asilkan mereka tidak bole& salin% inter7

operasi.

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*. T%$ N$t+or L'&$r – is responsible for t&e source7to7

destination delier# of a packet across

multiple network links.

,.T%$ Tr'!port L'&$r

– is responsible for t&e source7to7destination delier# of t&e entiremessa%e.


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Conto& soalan peperiksaan6/plain t&e purpose of arious la#ers8

Terangkan secara ringkas, fungsi/tujuan bagi setiaplapisan?

-. T%$ S$!!#o L'&$r – establis&es maintains and s#nc&roni:es t&e

interactions between communicatin% deices.

.T%$ Pr$!$t't#o L'&$r – ensures interoperabilit# between communicatin%

deices t&rou%& transformation of data into amutuall# a%reed7upon format.

/.T%$ App#c't#o L'&$r – enables t&e users to access t&e network.

;


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It$r't#o' St'0'r0!Or'#'t#o3!(ISO)

• '&e International Standards

Organization's(ISO) ,S* model seres

as a standard template for describin%

a network protocol stack.

<


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*s learnin% ,S* la#er isimportant8

1. '&e ,S* =eference -odel proides t&e

basis for understandin% &ow tec&nolo%ies

like 6t&ernet &as some important

similarities>

1?


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*s learnin% ,S* la#er isimportant8

2. *t e/plains &ow a (C can communicate usin% an# of

seeral di@erent sets of protocols een

simultaneousl#>

3. *t is an important part of understandin% t&e di@erences

between interconnection deices suc& as repeaters

&ubs brid%es switc&es and routers> and it also

e/plains &ow man# W"N tec&nolo%ies interoperate.

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'&e purpose of ,S* model

•U can take t&ese as an answer for 9uestions likeA w&at is t&epurpose of ,S* model8A

1. 'o promote t&e %oal of communications between di@erent t#pes ofs#stems b# encoura%in% t&e deelopment of internetworkin% deices.

2. 'o make sure t&at all functions needed for communications areaddressed and t&at none are left out.

3. 'o aoid duplication of functions t&ereb# increasin% eBcienc#.

4. 'o desi%n independence for eac& la#er from ot&er la#ers. '&is facilitatest&e interoperabilit# of products from di@erent manufacturers andinsures t&at t&e end7user can substitute one endors product foranot&er.

!. 'o produce a learnin% tool t&at can be used to understand &ow

communications in modern computer s#stems works. 12


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M$t%o0! o4 "!# t%$ OSI5o0$

• '&ere are THREE(*) di@erent wa#s to use t&e ,S*model

1. Botto5 "p D troubles&ootin% b# %oin% from t&e psical la#er

la#er 1 up to t&e application la#er la#er

2. Top 0o+ 7 troubles&ootin% b# %oin% from t&e applicationla#er la#er down to t&e psical la#er la#er 1

*. D#6#0$ '0 Co7"$r D in t&is met&od #ou start wit&w&ateer la#er #ou feel is most likel# t&e cause of t&eproblem t&en moe in w&ateer direction #ou feel is t&e morelikel# cause of t&e issue eit&er up or down t&e ,S* model

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2.1.2 Define specific functions

belonging to each OSI Model layer.


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"pplication la#er

L'&$rD$!cr#pt#o8$&+

or0!Protoco!

D$6#c$!8co5po$t!

D't'$c'p!"'t#o

"pplication

• (roides aninterface for a

serice tooperate• Communicatio

n partneridenti0cation

• E''(• 'elnet

• F'(• 'F'(• SN-(

Userinformation

and data

1!


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(resentation la#er

L'&$rD$!cr#pt#o8

$&+or0!Protoco!

D$6#c$!8co5po$t

!

D't'$c'p!"'t

#o

(resentation

• +ataformat 0le

formats• 6ncr#ption

translation andcompressi

on• +ata

format ande/c&an%e

G(6H5-( '*FF

(*C' -(6HW-I "I*"SC**65C+*C-*+* W"I

+ata

1$


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Session la#er

La#er+escription)ke#wor

ds(rotocols

+eices)components

+ataencapsulatio

n

Session

• Keeps datastreams

separatesessionidenti0cation

• Set upmaintain andtear down

communication sessions

• SJL• NFS

• "S(• =(C•

window+ata

1


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'ransport la#er

La#er+escription)ke#wor

ds(rotocols

+eices)components

+ataencapsulati

on

'ranspo

rt

• =eliableconnection

oriented andunreliableconnectionlesscommunications

• 6nd7to7endow control• (ort and

socketnumbers

• Se%mentation

se9uencin%and

• 'C(connection7

oriented• U+(connectionless

Se%ments

1;


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+ata Link la#er

La#er +escription)ke#words (rotocols +eices)components

+ata

encapsulation

+atalink

• Conert bits intob#tes and b#tes intoframes

• -"C address

&ardware address• Lo%ical network

topolo%#• -edia access• Flow control

o "cknowled%em

entso 5u@erin%o Windowin%

• (arit# and C=C

• L"N protocols ;?2.2LLC;?2.36t&ernet

;?2.!'oken=in%;?2.11Wireless

• W"Nprotocols

E+LC (((Frame =ela#*S+N "'-

• Network*nterfaceCard N*Ctransceier

s• Switc&• 5rid%e

Frames

2?


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(sical la#er

La#er +escription)ke#words (rotocols +eices)components

+ataencapsulation

(sical

• -oe bits acrossmedia

• Cables connectors

pin positions• 6lectrical si%nals

olta%e bits#nc&roni:ation

• (sical topolo%#network la#out

• 6*")'*"232serialsi%nalin%

• I.3!modemsi%nalin%

• Cat!• =G4!

• 'ransmissionmedia cableand wires

• -ediaconnectors

• 'ransceiersincludin%transceiersbuilt into N*Cs

• -odems• =epeaters• Eubs• -ultiple/ers• CSUs)+SUs• Wireless

"ccess (oints

5its

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Juestions

4. W&ic& ,S* la#er is responsible foraddin% a &eader t&at includesroutin% information8

Network La#er!. W&ic& ,S* la#er is considered t&e

media access control la#er8

+ata Link La#er$. 'C( functions at w&at la#er of t&e

,S* model8

'ransport La#er 23


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Juestions

. W&ic& la#er is responsible for conertin%data packets from t&e +ata Link la#er intoelectrical si%nals 8

;. "t w&ic& la#er is routin% implementedenablin% connections and pat& selectionbetween two end s#stems. 8


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Juestions

1?.W&ic& la#er is responsible for creatin%mana%in% and terminatin% sessionsbetween applications 8

11.W&ic& la#er proides lo%ical addressin%t&at routers will use for pat&determination 8

12.W&ic& la#er speci0es olta%e wire speedand pinout cables and moes bits betweendeices 8

2!


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2.1.* DESCRIBE HOW TWO NETWORKNODES COMMUNICATE THROU:H THEOSI MODEL.


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Data o! t"roug" t"e OSI #odel

2


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Communication between s#stems

2;


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2<


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,S* =6F6=6NC6-,+6L

=6"L W,=L+6JU*I"L6N' '"SKS

'C()*( (=,',C,L

"pplication(ro%ram to pro%ramtransfer of

information

"pplication(resentation 'e/t formattin% anddispla# codeconersion

Session

6stablis&in%maintainin% andcoordinatin%communication

'ransport"ccurate delier#serice 9ualit# 'ransport

Network 'ransport routes

messa%e &andlin%and transfer

*nternet

+ata LinkCodin% addressin%and transmittin%information Network

*nterface(& sical '&e &ardwareconnections t&e N*C

3?


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2.1., DESCRIBE THE STRUCTURE ANDPURPOSE OF DATA PACKETS ANDFRAMES.

'& d f d


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'&e structure and purpose of datapackets


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• *t turns out t&at eer#t&in% #ou do on t&e

*nternet inoles p'c$t!.

• For e/ample eer# Web pa%e t&at #ou receie

comes as a series of packets and eer# e7mail

#ou send leaes as a series of packets. Networkst&at s&ip data around in small packets are called

p'c$t !+#tc%$0 $t+or!.

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2.1.4 6/plain t&e structure andpurpose of data packets and frames.


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• " packet is a basic unit of communication oer a

di%ital network.

• " packet is also called a data%ram a se%ment a

block a cell or a frame dependin% on t&e

protocol.

• W&en data &as to be transmitted it is broken

down into similar structures of data w&ic& are34

+ata (acket

http://voip.about.com/od/voipbasics/g/protocoldef.htmhttp://voip.about.com/od/voipbasics/g/protocoldef.htm


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• ,n t&e *nternet t&e network breaks an e7

mail messa%e into parts of a certain si:e in

b#tes.

• '&ese are t&e packets.

3!

+ata (ackets and Frames


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• 6ac& packet carries t&e information

t&at will &elp it %et to its destination

77 t&e senderMs *( address t&e

intended receierMs *( address

somet&in% t&at tells t&e network &ow

man# packets t&is e7mail messa%e

&as been broken into and t&e number3$


http://computer.howstuffworks.com/question549.htmhttp://computer.howstuffworks.com/question549.htm


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• '&e packets carr# t&e data in t&e protocols t&at t&e

*nternet uses 'ransmission Control (rotocol)*nternet

(rotocol 'C()*(.

• 6ac& packet contains part of t&e bod# of #our messa%e.

• " t#pical packet contains per&aps 1??? or 1!?? b#tes.

3


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P'c$t! '0 protoco!

• (ackets ar# in structure dependin% on t&e

protocols implementin% t&em.

• Io*( uses t&e *( protocol and &ence *( packets.

• ,n an 6t&ernet network for e/ample data is

transmitted in 6t&ernet frames.

3;


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Str"ct"r$ o4 p'c$t!

• '&e structure of a packet depends on t&e t#pe of

packet it is and on t&e protocol.

• Normall# a packet &as a &eader and a pa#load.

• '&e &eader keeps oer&ead information about t&epacket t&e serice and ot&er transmission7related

t&in%s.

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Structure of packets

• For e/ample an *( packet includes

– '&e source *( address

– '&e destination *( address

– '&e se9uence number of t&e packets

– '&e t#pe of serice

– Fla%s

– 6tc

– '&e pa#load is t&e data it carries.

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$rotocol

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• '&ere are rules %oernin% &ow data is

transferred oer networks &ow t&e# are

compressed &ow t&e# are presented on

t&e screen and so on.

• '&ese set of rules are called protoco!.

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(rotocol


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(rotocol

• '&ere are man# protocols eac& one %oernin%

t&e wa# a certain tec&nolo%# works.

• For e/ample t&e *( protocol de0nes a set of

rules %oernin% t&e wa# computers use *(

packets to send data oer t&e *nternet or an#

ot&er *(7based network.

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(rotocol

• It also defines addressing in IP. Likewise, we have other protocols like:

1. TCP: Transmission Control Protocol, used for the reliable transmission of data

over a network.

2. HTTP: Hypertext Transfer Protocol, used for transmitting and displaying

information in the form of web pages on browsers.

3. FTP: File Transfer Protocol, used for file transfer uploading and downloading!

over the Internet

4. SMTP: Simple Mail Transfer Protocol, used for email

5. Eternet: "sed for data transmission over a L#$.

!. "i#Fi: %ne of the wireless protocols.

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2.1.- RELATE TWO TYPES OFADDRESSIN: CO9ERED BY THE OSIMODEL.


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2.1.! 6/plain TWO (2) t#pes ofaddressin% coered b# t&e ,S* -odel.

• &ach node has T"$%2& types of

addresses:

1. Network address: follows hierarchicaladdressing scheme

• 'an be assigned through %( software

• $etwork layer addresses, logical

addresses, or virtual addresses

2. Physical address

4$


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2.2 UNDERSTAND A LOCALWIRED NETWORK

2.2.1 6/plain t&e -"C address of a Eost usin% ipcon0% )all command.

2.2.2 =elate a standard *666 ;?2.3 6t&ernet Frame based on a %iensource and destination deices.

2.2.3 Hie lo%ical address of a computer.

2.2.4 Hie *( address of a computer.


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2.2.1 6/plain t&e -"C address of aEost usin% ipcon0% )all command.

• Physical addressing

– )#' address )edia #ccess 'ontrol!

– &thernet communication: – each interface has a )#' address

– each device may look at the data, but only the interface that

matches the destination )#' will respond


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• Ipconfig:

– Is used to find out your current *'P+IP settings.

– ith IP'%$-I you can find out your IP

#ddress, find your /efault ateway and find

your (ubnet )ask.

– *his is a very handy network tool for finding

your local IP address.


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ipcon0% command


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• ipconfig +all:

– *o display all your IP information for all

adapters.

– ith ipconfig +all you can also find out your

/$( (erver and )#' #ddress.

– *his will show your full *'P+IP configuration for

all adapters on your indows machine.


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2 2 2 =elate a standard *666 ;?2 3 6t&ernet


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2.2.2 =elate a standard *666 ;?2.3 6t&ernetFrame based on a %ien source anddestination deices.

• Pream'le – beginning of the timing• SF( %Start Frame (elimiter& – marks the end of the timing, but

beginning of the frame• (estination M)C• So*rce M)C

• +en,t-Type – Length – tells which protocol receives the data – *ype – number of bytes of data

• Encaps*lation – packet of information• FCS %Frame Cec Se/*ence& – checks for damaged frames

2 2 3 Hi l i l dd f


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2.2.3 Hie lo%ical address of acomputer.

• )#' vs. IP

• IP #ddress Logical #ddress!:

– assigned based on where the host is located

– assigned by the administrator

• Parts of an IP address: – 0etor – same for all hosts connected to the L#$

– Host – uni0ue to each host on the network


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2.2.4 Hie *( address of a computer.

• # logical address is:

– the address that is given or assigned to a device

which registers its presence on the internet highway.

– #t a particular time this address will be uni0ue for the

device but it may change at some times in future.

– IPv1 is an e2ample of Logical #ddress.


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2.* UNDERSTAND BASIC CONCEPT OFINTERNET CONNECTION ANDINFORMATION SENT ACROSS INTERNET


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2.*.1 LIST INTERNETSER9ICE PRO9IDER (ISPS)

* t t S i ( id *S( i


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*nternet Serice (roiders *S( in

-ala#sia

1. C$co5 Bro'0;'0

– 5roadband serices b# Celcom based on ES+("

2. ##! Bro'0;'0 – 5roadband serices b# -a/is based on ES+("

-. P1

– Wi7Fi and Wi-a/ 5roadband b# Hreen (acket

* t t S i ( id *S( i


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*nternet Serice (roiders *S( in

-ala#sia

!<

. P$'FON

– Fibre Speed *nternet 5roadband

/. REDto$

– 'elecommunication solutions proider Io*(*nternet Leased Lines Wi-a/

?. Str$'5&>

– 5roadband access "+SL b# '-

@. TIME Bro'0;'0 – one Fusion 5i:Net EomeNet NetLink


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2.*.2 DESCRIBE THE RELATIONSHIPBETWEEN ISP AND INTERNET


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4.1.3 '&e *S(s =elations&ip Wit& t&e *nternet

• *S(s use a (,( (ost ,Bce (rotocol to proideserice to end users.

• '&ere are man# (,(s in an *S(s network.


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(ost ,Bce (rotocol (,(

*n computin% t&e Po!t Oc$Protoco POP is an application7la#er *nternet standard protocol used

b# local e7mail clients to retriee e7mail from a remote serer oer a

'C()*( connection.

(,( and *-"( *nternet -essa%e"ccess (rotocol are t&e two most

prealentcommon *nternet standard


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(ost ,Bce (rotocol (,(

Iirtuall# all modern e7mail clients andserers support bot&. '&e (,( protocol &as been deeloped

t&rou%& seeral ersions wit& ersion 3(,(3 bein% t&e current standard.

Like *-"( (,(3 is supported b# mostwebmail serices suc& as EotmailHmail and Oa&ooP -ail.

$3


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2 3 3 I5port'c$ o4 t%$ It$r$t


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2.3.3 I5port'c$ o4 t%$ It$r$tProtoco (IP)

• -ust run *nternet (rotocol *( software tocommunicate on *nternet.

• *( protocol is one of t&e 'C()*( 'ransmission Control(rotocol ) *nternet (rotocol (rotocols .

• "s 6t&ernet uses Frames *( uses (ackets.

• 6ac& *( packet must contain a alid source and

destination *( address.

2 3 3 I5port'c$ o4 t%$ It$r$t


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2.3.3 I5port'c$ o4 t%$ It$r$tProtoco (IP)

• The IP Packet (datagram)• Eas a &eader

w&ic& contains t&esource anddestination *(

addresses.

• *( addresses mustbe uni9ue on t&e*nternet.

• Computers in&omes smallbusinesses andot&er or%ani:ationsobtain t&eir *(

con0%uration from


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2.*., EPLAIN THE PACKETS TRA9ELTHROU:H THE INTERNET BY USIN:PIN: AND TRACEROUTE

T%$ Ro"t# Proc$!! P# A0


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T%$ Ro"t# Proc$!! P# A0Tr'c$ro"t$

3. *n t&is e/ample t&e &ost wants to send data to a deiceat *( address 2?.1.1.2.

4. '&e &ost is attac&ed to onl# one network 1?.?.?.? );.

!. '&e &ost will t&en send t&e data to its default %atewa#w&ic& in t&is case &appens to be a Cisco router.

$. W&en t&is data%ram is sent b# t&e &ost t&e destination

*( address will be t&at of t&e &ost at 2?.1.1.2.

. Eoweer t&e destination -"C address will be t&at oft&e router interface closest to t&e sendin% &ost.


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;. '&e router receies t&e data%ram RunpacksA it


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% p and sends it to t&e routin% process.


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U!# PIN: A0 TRACEROUTE ToT$!t N$t+or Co$ct#6#t&

• *C-( *nternet Control -essa%e (rotocol o@ers two

network connectiit# testin% functions.

• '&e ping command sends 0e *C-( packets to t&e

intended destination.

• (in% will t&en return one of seeral s#mbols to indicate

w&et&er *( connectiit# e/ists and if not a clue to

w&at t&e issue is.

• '&e pin% is an *C-( 6c&o =e9uest> t&e pin% repl# is an

*C-( 6c&o =epl#.1

Consider our earlier e/ample. *f t&e &ost on


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Consider our earlier e/ample. *f t&e &ost onnetwork 1?.?.?.? ); &as trouble reac&in% t&e &oston 2?.?.?.? ); pin% &elps dia%nose t&e problem.

2


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3. Ping process

3

• '&e two %eneral replies from a pin% are

RPPPPPA and R..A.

• '&e e/clamation points indicate *(

connectiit# e/ists between t&e &osts> 0e

periods indicate t&at t&e pin% packets were

unable to 0nd t&e destination &ost.


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4. *raceroute

4

• '&e second *C-( tool #ou s&ould be

familiar wit& is traceroute%

• W&ere pin% simpl# tells #ou w&et&er *(

connectiit# is or is not present traceroute

displa#s t&e pat& t&e packet takes to reac&

its destination.


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'raceroute

!

• 'raceroute works b# sendin% out *C-(

packets wit& a 'ime 'o Lie ''L of one to

0nd t&e 0rst step to t&e 0nal destination.

• *t will t&en send a packet wit& a ''L of

two and t&e ''L alue increases until t&e

0nal destination is found.


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'raceroute

$

• W&en t&at &appens t&e entire pat& will be

displa#ed on #our console.

• *f t&e 0nal destination cannot be found asterisks

will start to appear on #our screen.

• '&is is a sort of error messa%e D it means t&e ''L

&as been e/ceeded.

• 'o abort a pin% or traceroute in pro%ress press

TC'=L7SE*F'7$ twice in rapid succession.


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'raceroute

• " %reat R17273A met&od to troubles&oot

routin% problems

1. (in% t&e destination.

2. *f t&e pin%s dont come back run s"o! ip route

to make sure #our local deice &as a route to t&e

destination.

3. *f a route e/ists use traceroute to determine

w&ic& downstream router cant route t&e packet.

i


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Juestion

1. W&ic& de0nition describes t&e term*nternet8

". a %roup of (Cs connected to%et&er on

a L"N5. a %roup of (Cs connected to%et&er b#

an *S(

C. a network of networks t&at connectscountries around t&e world

+. a worldwide collection of networkscontrolled b# a sin%le or%ani:ation

;

J i


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Juestion

2. W&at t#pe of connection point is apoint of presence (,(8

". between a client and a &ost

5. between two local networksC. between a computer and a switc&

+. between an *S( and a &ome7based L"N

<

J i


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Juestion

!. W&ic& THREE(*) elements arere9uired to successfull# connect tot&e *nternet8 C&oose t&ree.

". an *( address5. 0le s&arin% enabled

C. a network connection

+. serer serices enabled6. access to an *nternet serice proider

F. an address obtained directl# from t&e =*=

;?

"


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"nswer

1. C

2. +

3. " 5 and 6

4. C

!. " C and 6

;1


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2., UNDERSTANDNETWORK SER9ICES

2.4.1 +e0ne +omain Name Serice +NS.

2.4.2 =elate pin% command a browser and nslookup to identif# t&e relations&ipbetween domain names and *( addresses.

2.4.3 6/plain +NS in a L"N.

2.4.4 +escribe e7mail protocols in clients and serers S-'( (,(3 and *-"(4


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2.,.1 DEFINE DOMAINNAME SER9ICE (DNS).

2 , 1 + 0 D i N S


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2.,.1 +e0ne Domain Name S#stem

• +e0nition – & sste# for conerting "ost na#es and

do#ain na#es into I$ addresses on t"e

Internet or on local net!orks t"at use t"eT$/I$ protocol%

– Sistem untuk menukar nama &os dan

nama domain ke dalam alamat *( di*nternet atau pada ran%kaian tempatan#an% men%%unakan protokol 'C( ) *(.

;4


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D i N S t


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Domain Name S#stem

• *n t&is pot&etical e/ample+++.co5p'&.co5 would be conerted intot&e *( address 2?4.?.;.!1.

• Wit&out +NS #ou would &ae to t#pe t&e fournumbers and dots into #our browser to retrieet&e Web site w&ic& of course #ou can do.

• 'r# 0ndin% t&e *( of a faourite Web site and t#pein t&e dotted number instead of t&e domainnameP

;$


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2.,.2 RELATE PIN: COMMAND A

BROWSER AND NSLOOKUP TOIDENTIFY THE RELATIONSHIPBETWEEN DOMAIN NAMES AND IPADDRESSES.

=elate pin% command to identif# t&el ti &i b t d i d *(


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relations&ip between domain names and *(addresses.

• '&e PIN: command can be used toc&eck if a domain name is resolin%to an *( address and if t&at *(

address can be reac&ed from #ourmac&ine.

=elate a browser and nslookup to identif#t& l ti &i b t d i d


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t&e relations&ip between domain names and*( addresses.

• *n Windows #ou can do plent# oft&in%s usin% command line.

• Conertin% a domain name to its *(

address usin% t&e !oo"pco55'0 is one of t&em.

• Oou can also 0nd *( address of an#

websites &ost mac&ine.

Eeres is t&e step b# step


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Eere s is t&e step b# step

procedure

1. Click on Start button and t#pe cmdin t&e searc& bo/. (ress R6nterA.


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2. Windows command prompt willopen. Now t#pe nslookupftp.#a&oo.com and press enter.


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3. *t will s&ow #ou Oa&oo F'( *( address. '&isis *( address of t&e serer w&ere#a&oo.com is &osted. Similarl# #ou can0nd &ost mac&ines for an# ot&er website.


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4. *f #ou want to look up *( address ofa website t&en t#pe nslookup in t&ecommand prompt and press enter.


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!. Now enter t&e domain name of an#website and press enter. *t will s&ow#ou t&e *( address of t&at particular

site. For e/ample #ou t#ped%oo%le.com and pressed enter. *treturned Hoo%les *( address

2?


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• Similarl# #ou can conert an# ot&er domainname into its *( address. Oou can also c&eck t&eresult b# t#pin% t&e *( address in t&e browseraddress bar.

• Now for t&e more tec& sa# folks amon% #out&e nslookup command is used for testin% out+NS serers.

• =emember for websites t&at dont &ae adedicated *( address #ou could %et di@erentresults eac& time #ou use t&is command.


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2.,.* EPLAIN DNS IN ALAN.


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2.,., DESCRIBE EMAILPROTOCOLS IN CLIENTS ANDSER9ERS SMTP POP* ANDIMAP,

O6$r6#$+


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O6$r6#$+

• S-'( (,(3 and *-"( are 'C()*( protocolsused for mail delier#.

• *f #ou plan to set up an email serer suc&as -ail Serer #ou must know w&at t&e#are used for.

• 6ac& protocol is Vust a speci0c set ofcommunication rules between computers.


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p(rotocol

• S*T$ stands for Si#ple *ail Transfer$rotocol%

• S*T$ is used !"en e#ail is delieredfro# an e#ail client, suc" as Outlook+press, to an e#ail serer or !"en

e#ail is deliered fro# one e#ailserer to anot"er%

• S-'( uses port 2! 1??

POP* (Po!t Oc$ Protoco)


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POP* (Po!t Oc$ Protoco)

• POP3 stands for Post Office Protocol .

• POP3 allows an email client to download an email from an email server.

•*he P%P5 protocol is simple and does not offer many features e2cept fordownload.

• Its design assumes that the email client downloads all available email from

the server, deletes them from the server and then disconnects.

• P%P5 normally uses port 336.

1?1

IMAP (It$r$t M$!!'$ Acc$!!


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Protoco)

• I*&$ stands for Internet Message Access Protocol.

• I*&$ s"ares #an si#ilar features !it" $O$-%

• It, too, is a protocol t"at an e#ail client can use to do!nload e#ail

fro# an e#ail serer%

• Eoweer *-"( includes man# more features t&an (,(3.

• T"e I*&$ protocol is designed to let users keep t"eir e#ail on t"eserer%

• *-"( re9uires more disk space on t&e serer and more C(U resourcest&an (,(3 as all emails are stored on t&e serer. *-"( normall# usesport 143.

1?2


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2..1 COMPARE THE ADDRESSIN:

SCHEME OF TCP8IP TCP8IP CLASSESBINARY AND DOTTED DECIMALNOTATION SUBNET MASK.

2.$.1 Compare t&e addressin% sc&eme of 'C()*('C()*( classes binar# and dotted decimal notation


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'C()*( classes binar# and dotted decimal notationsubnet mask.

• 'C()*( uses 32 bits or four numbers

between ? and 2!! to address a

computer.

1?4

IP A00r$!!$!


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IP A00r$!!$!

• 6ac& computer must &ae an *( address before it can

connect to t&e *nternet.

• 6ac& *( packet must &ae an address before it can be

sent to anot&er computer.

• '&is is an *( address 1


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N"5;$r!

• 6ac& computer must &ae a uni9ue *( address.

• '&is is #our *( address 2*.?2.?/.12

• 'C()*( uses four numbers to address a computer. '&e numbers are alwa#s between ? and 2!!.

•*( addresses are normall# written as fournumbers separated b# a period like t&[email protected]?.1.-.

1?$

*2 B#t! G , B&t$!


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*2 B#t! G , B&t$!

• *n computer terms 'C()*( uses *2 ;#t! addressin%. ,ne ;&t$ is ; bits. 'C()*( uses, ;&t$!.

• ,ne b#te can contain 2!$ di@erent alues – ???????? ???????1 ??????1? ??????11

?????1?? ?????1?1 ?????11? ?????111

????1??? .......and all t&e wa# up to 11111111.

• Now #ou know w a 'C()*( address isfour numbers between ? and 2!!.

1?

N$t+or C'!!$!


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N$t+or C'!!$!

• *nternet addresses are allocated b# t&e *nterN*C &ttp))www.internic.net t&e or%ani:ation t&atadministers t&e *nternet.

• '&ese *( addresses are diided into classes.

• '&e most common of t&ese are classes " 5 andC.

• Classes + and 6 e/ist but are not %enerall# usedb# end users.

1?;

http://www.internic.net/http://www.internic.net/


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Followin% are t&e ran%es of Class " 5 and C*nternet addresses eac& wit& an e/ample


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*nternet addresses eac& wit& an e/ampleaddress

• C'!! A – networks use a default subnet mask of

2!!.?.?.? and &ae ?712 as t&eir 0rst

octet. – '&e address 1?.!2.3$.11 is a class "

address.

– *ts 0rst octet is 1? w&ic& is between 1

and 12$ inclusie.

11?

Followin% are t&e ran%es of Class " 5 and C*nternet addresses eac& wit& an e/ample


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• C'!! B – networks use a default subnet mask of

2!!.2!!.?.? and &ae 12;71


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• C'!! C – networks use a default subnet mask of

2!!.2!!.2!!.? and &ae 1


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• *n some scenarios t&e default subnet

mask alues do not 0t t&e needs of

t&e or%ani:ation because of t&e

psical topolo%# of t&e network or

because t&e numbers of networks or&osts do not 0t wit&in t&e default

subnet mask restrictions.113

'&e followin% table s&ows w&ic& b#tes of t&e *(address are assi%ned to #ou and t&e ran%e of

b it&i & b t t& t il bl f


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numbers wit&in eac& b#te t&at are aailable for #outo assi%n to #our &osts.

114

Class5#te 1ran%e

5#te 2ran%e

5#te 3ran%e

5#te 4ran%e

" ? 7 12 1 7 2!4 1 7 2!4 1 D 2!4

5 12; 7 1


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+otted +ecimal Notation

• *( addresses are normall# e/pressed indotted7decimal format wit& four numbers

separated b# periods suc& as

1


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5inar# and +otted +ecimal Notation

• For e/ample t&e dotted7decimal *( address

1


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5inar# and +otted +ecimal Notation

• '&ese EI:HT(?) bit sections are known as octets.

• '&e e/ample *( address t&en becomes11??????.1?1?1???.?1111?11.1????1??.

• '&is number onl# makes a little more sense so formost uses conert t&e binar# address into dotted7decimal format 1


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IP A00r$!!# Sc%$5$

• "n *( address &as TWO(2) parts.

• '&e r!t part of an *( address is

used as a network address t&e

!$co0 part as a &ost address.

11;

IP A00r$!!# Sc%$5$


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IP A00r$!!# Sc%$5$

• *f #ou take t&e e/ample1


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*ncrements of an *( "ddress

• ?.?.?.?• ?.?.?.1

• increment 2!2 &osts

• ?.?.?.2!4

• ?.?.?.2!!

• ?.?.1.?

• ?.?.1.1

• increment 2!2 &osts

• ?.?.1.2!4

• ?.?.1.2!!• ?.?.2.?

• ?.?.2.1

• increment 4 billion &osts

• 2!!.2!!.2!!.2!!12?

S";$t M'!


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S";$t M'!

• '&e second item w&ic& is re9uired for

'C()*( to work is t&e subnet mask.

• '&e subnet mask is used b# t&e

'C()*( protocol to determine w&et&er

a &ost is on t&e local subnet or on aremote network.

121

S";$t M'!


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S"; $ '!

• *n 'C()*( t&e parts of t&e *( addresst&at are used as t&e network and&ost addresses are not 0/ed so t&e

network and &ost addresses aboecannot be determined unless #ou&ae more information.

• '&is information is supplied inanot&er 327bit number called a

subnet mask122

S";$t M'!


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• *n t&is e/ample t&e subnet mask is2!!.2!!.2!!.?.

• *t is not obious w&at t&is number

means unless #ou know t&at 2!! inbinar# notation e9uals 11111111> sot&e subnet mask is

123

S";$t M'!


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• Linin% up t&e *( address and t&esubnet mask to%et&er t&e networkand &ost portions of t&e address can

be separated

124

S";$t M'!


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• '&e 0rst 24 bits t&e number of onesin t&e subnet mask are identi0ed ast&e network address wit& t&e last ;bits t&e number of remainin% :eros

in t&e subnet mask identi0ed as t&e&ost address. '&is %ies #ou t&efollowin%

12!

S";$t M'!


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•So now #ou know for t&is e/ample usin% a2!!.2!!.2!!.? subnet mask t&at t&enetwork *+ is 1


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• "lmost all decimal subnet masksconert to binar# numbers t&at areall ones on t&e left and all :eros on

t&e ri%&t.• Some ot&er common subnet masks

are

12

U!$! o4 S";$t M'!!


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1. *denti0es a Network.2. *solates t&e Network *+ and Eost *+.

3. +etermines t&e number of

&ost)terminals t&at could be used ont&e same network.

4. =educes Network traBc.

12;


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"NO JU6S'*,N)C,--6N'8

12<

Juestions


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J

1. *nternet (rotocol *( addresses are &ow man#bits lon%8

2. '&e address $;.!$.1;


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J

!. W&at is t&e binar# number1?1?1?11 in base 1?8

$. W&at is t&e base 1? number 2!! inbinar#8

. W&at is t&e network address for t&e 'C()*( address 1


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2..2 W%'t #! P";#c IP '00r$!!8


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• (ublic *( "ddresses also known as Static *("ddresses are *( addresses t&at are isible to t&epublic.

• 5ecause t&ese *( addresses are public t&e# allowot&er people to know about and access #ourcomputer like a Web serer.

• *n some cases #ou do not want people to access#our computer or #ou want to restrict certainindiiduals from accessin% #our computer or serer.

133

W%'t #! Pr#6't$ IP '00r$!!8


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• '&ese addresses can be used on apriate network but t&e#re notroutable t&rou%& t&e public *nternet.

• '&is not onl# creates a measure ofmuc&7needed securit# but it also

conenientl# saes aluable *(address space.

134

C"rr$t Pr#6't$ IP '00r$!!$! '!4oo+!


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4oo+!

• C'!! A – 1?.?.?.? t&rou%& 1?.2!!.2!!.2!!

• C'!! B – 12.1$.?.? t&rou%& 12.31.2!!.2!!

• C'!! C – 1


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2..* EPLAIN UNICAST BROADCAST

AND MULTICAST ADDRESSES

U#c'!t


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• " unicast *( address is an *( addressuni9uel# identif#in% a &ost in a network.

• '&e data%ram wit& a unicast *( addressis receied and processed b# onl# asin%le &ost.

• For e/ample t&e *( address1


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• '&e data%ram wit& a broadcast *(address is receied and processed b#

all t&e &osts in t&e local network.

• For e/ample t&e *( addresses

2!!.2!!.2!!.2!!1


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• " multicast address is an *( addressidentif#in% a particular %roup of &ostsin network.

• '&is %roup of &osts is called amulticast %roup.

• For e/ample t&e *( address22!.2.1??.1 is a multicast *( address.

13<


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2.., RELATE HOW IP ADDRESSES

ARE OBTAINEDSTATIC ADDRESSESDYNAMIC ADDRESSES

2.., W%'t 'r$ >$0 '00&'5#c IP '00r$!!$!


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0&'5#c IP '00r$!!$!

• *n a traditional 'C()*( network arc&itecture eac&computer is assi%ned a permanent *( address.

• '&is re9uires manual con0%uration of eac& and

eer# computer.

• ,nce t&e address is assi%ned it will not c&an%eunless someone does it manuall#.

• *t is called a 0/ed *( address.

141

W%'t 'r$ >$0 '0 0&'5#c IP'00r$!!$!


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'00r$!!$!

• W&en &undreds or t&ousands of computers areinoled t&is can be a lot of work.

• Sometimes networks are recon0%ured and lar%enumbers of mac&ines must be %ien new *( addresses.

• 6ac& time a computer is added care must be taken toensure t&at it does not use an *( address alread#assi%ned to anot&er computer on t&e same network.

• 'o improe t&is situation +#namic Eost Con0%uration

(rotocol +EC( was deeloped.

142

W%'t 'r$ >$0 '0 0&'5#c IP'00r$!!$!


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'00r$!!$!

• " +EC( serer is a software pro%ram t&atassi%ns *( addresses to computers wit& nomanual interention.

• '&is &as tremendous adanta%es in irtuall#an# network enironment.

• "dministrators of lar%e networks sae man#&undreds of &ours per #ear oer manualcon0%uration of computers.

143

W%'t 'r$ >$0 '0 0&'5#c IP'00r$!!$!


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'00r$!!$!

• Computers ma# be added or remoed wit&no impact on t&e network con0%uration andno concerns about address conict.

• Users on een t&e smallest networks bene0tas t&e# do not need to know &ow tocon0%ure a 'C()*( control panel.

• " computer on suc& a network is said to&ae ' 0&'5#c IP '00r$!!.

144

D&'5#c IP A00r$!!$!


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• '&e bi%%est adanta%es of +#namic *(

"ddressin% are

#. $!! !$c"r#t& r#!.

ii. t&e co5p"t$r #! '!!#$0 ' $+ IP

'00r$!! $'c% t#5$ t%$ c"!to5$r o! o.

iii. t&e# are co!t $J$ct#6$.

i. t&ere is '"to5't#c $t+or co"r't#o.

14!

D&'5#c IP A00r$!!$!


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• *n contrast Dna#ic I$ addressin% s&ould

not be used for I,*( I(N pla#in% online

%ames or %ame &ostin% because +#namic

*( addressin% is less reliabletrusted t&en

Static *( addressin% and could cause t&e

serice to disconnect w&ile #ou are on a

I,*( I(N or %amin%.

14$

2../ D&'5#c Ho!t Co"r't#o Protoco (DHCP)

!$r6$r


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!$r6$r

• D&'5#c Ho!t Co"r't#o Protoco

(DHCP) is a network protocol t&at enables

a serer to automaticall# assi%n an *(

address to a computer from a de0ned

ran%e of numbers i.e. a scope

con0%ured for a %ien network.

14

D&'5#c Ho!t Co"r't#oProtoco (DHCP) !$r6$r


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o oco ( C ) !$ $

• " +EC( Serer assi%ns *( addressesto client computers.

• '&is is er# often used in enterprisenetworks to reduce con0%uratione@orts.

• "ll *( addresses of all computers arestored in a database t&at resides on

a serer mac&ine14;


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DHCP S$r6$r


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• ,t&er information can be proided aswell suc& as +omain Name Serice+NS serer addresses and Windows

*nternet Name Serice W*NS sereraddresses.

• '&e s#stem administrator con0%urest&e +EC( serer wit& t&e options

2 the Open Systems Interconnection (Osi) Model and Network Protocols

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