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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.
4
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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.
11
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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"$r D in t&is met&od #ou start wit&w&ateer la#er #ou feel is most likel# t&e cause of t&eproblem t&en moe in w&ateer direction #ou feel is t&e morelikel# cause of t&e issue eit&er up or down t&e ,S* model
13
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2.1.2 Define specific functions
belonging to each OSI Model layer.
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"pplication la#er
L'&$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
21
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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$. 'C( functions at w&at la#er of t&e
,S* model8
'ransport La#er 23
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Juestions
. W&ic& la#er is responsible for conertin%data packets from t&e +ata Link la#er intoelectrical si%nals 8
;. "t w&ic& la#er is routin% implementedenablin% connections and pat& selectionbetween two end s#stems. 8
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Juestions
1?.W&ic& la#er is responsible for creatin%mana%in% and terminatin% sessionsbetween applications 8
11.W&ic& la#er proides lo%ical addressin%t&at routers will use for pat&determination 8
12.W&ic& la#er speci0es olta%e wire speedand pinout cables and moes bits betweendeices 8
2!
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2.1.* DESCRIBE HOW TWO NETWORKNODES COMMUNICATE THROU:H THEOSI MODEL.
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Data o! t"roug" t"e OSI #odel
2
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Communication between s#stems
2;
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2<
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,S* =6F6=6NC6-,+6L
=6"L W,=L+6JU*I"L6N' '"SKS
'C()*( (=,',C,L
"pplication(ro%ram to pro%ramtransfer of
information
"pplication(resentation 'e/t formattin% anddispla# codeconersion
Session
6stablis&in%maintainin% andcoordinatin%communication
'ransport"ccurate delier#serice 9ualit# 'ransport
Network 'ransport routes
messa%e &andlin%and transfer
*nternet
+ata LinkCodin% addressin%and transmittin%information Network
*nterface(& sical '&e &ardwareconnections t&e N*C
3?
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2.1., DESCRIBE THE STRUCTURE ANDPURPOSE OF DATA PACKETS ANDFRAMES.
'& d f d
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32
'&e structure and purpose of datapackets
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• *t turns out t&at eer#t&in% #ou do on t&e
*nternet inoles p'c$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 $t+or!.
33
2.1.4 6/plain t&e structure andpurpose of data packets and frames.
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• " packet is a basic unit of communication oer a
di%ital network.
• " packet is also called a data%ram a se%ment a
block a cell or a frame dependin% on t&e
protocol.
• W&en data &as to be transmitted it is broken
down into similar structures of data w&ic& are34
+ata (acket
http://voip.about.com/od/voipbasics/g/protocoldef.htmhttp://voip.about.com/od/voipbasics/g/protocoldef.htm
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• ,n t&e *nternet t&e network breaks an e7
mail messa%e into parts of a certain si:e in
b#tes.
• '&ese are t&e packets.
3!
+ata (ackets and Frames
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• 6ac& packet carries t&e information
t&at will &elp it %et to its destination
77 t&e senderMs *( address t&e
intended receierMs *( address
somet&in% t&at tells t&e network &ow
man# packets t&is e7mail messa%e
&as been broken into and t&e number3$
+ata (ackets and Frames
http://computer.howstuffworks.com/question549.htmhttp://computer.howstuffworks.com/question549.htm
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+ata (ackets and Frames
• '&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$t!
• '&e structure of a packet depends on t&e t#pe of
packet it is and on t&e protocol.
• Normall# a packet &as a &eader and a pa#load.
• '&e &eader keeps oer&ead information about t&epacket t&e serice and ot&er transmission7related
t&in%s.
3<
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Structure of packets
• For e/ample an *( packet includes
– '&e source *( address
– '&e destination *( address
– '&e se9uence number of t&e packets
– '&e t#pe of serice
– Fla%s
– 6tc
– '&e pa#load is t&e data it carries.
4?
l
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$rotocol
41
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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!.
42
(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.
43
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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#$.
!. "i#Fi: %ne of the wireless protocols.
44
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2.1.- RELATE TWO TYPES OFADDRESSIN: CO9ERED BY THE OSIMODEL.
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2.1.! 6/plain TWO (2) t#pes ofaddressin% coered b# t&e ,S* -odel.
• &ach node has T"$%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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*nternet addresses eac& wit& an e/ampleaddress
• C'!! B – networks use a default subnet mask of
2!!.2!!.?.? and &ae 12;71
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*nternet addresses eac& wit& an e/ampleaddress
• 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$.?.? t&rou%& 12.31.2!!.2!!
• C'!! C – 1
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2..* EPLAIN UNICAST BROADCAST
AND MULTICAST ADDRESSES
U#c'!t
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• " unicast *( address is an *( addressuni9uel# identif#in% a &ost in a network.
• '&e data%ram wit& a unicast *( addressis receied and processed b# onl# asin%le &ost.
• For e/ample t&e *( address1
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• '&e data%ram wit& a broadcast *(address is receied and processed b#
all t&e &osts in t&e local network.
• For e/ample t&e *( addresses
2!!.2!!.2!!.2!!1
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• " multicast address is an *( addressidentif#in% a particular %roup of &ostsin network.
• '&is %roup of &osts is called amulticast %roup.
• For e/ample t&e *( address22!.2.1??.1 is a multicast *( address.
13<
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2.., RELATE HOW IP ADDRESSES
ARE OBTAINEDSTATIC ADDRESSESDYNAMIC ADDRESSES
2.., W%'t 'r$ >$0 '00&'5#c IP '00r$!!$!
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0&'5#c IP '00r$!!$!
• *n a traditional 'C()*( network arc&itecture eac&computer is assi%ned a permanent *( address.
• '&is re9uires manual con0%uration of eac& and
eer# computer.
• ,nce t&e address is assi%ned it will not c&an%eunless someone does it manuall#.
• *t is called a 0/ed *( address.
141
W%'t 'r$ >$0 '0 0&'5#c IP'00r$!!$!
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'00r$!!$!
• W&en &undreds or t&ousands of computers areinoled t&is can be a lot of work.
• Sometimes networks are recon0%ured and lar%enumbers of mac&ines must be %ien new *( addresses.
• 6ac& time a computer is added care must be taken toensure t&at it does not use an *( address alread#assi%ned to anot&er computer on t&e same network.
• 'o improe t&is situation +#namic Eost Con0%uration
(rotocol +EC( was deeloped.
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'00r$!!$!
• " +EC( serer is a software pro%ram t&atassi%ns *( addresses to computers wit& nomanual interention.
• '&is &as tremendous adanta%es in irtuall#an# network enironment.
• "dministrators of lar%e networks sae man#&undreds of &ours per #ear oer manualcon0%uration of computers.
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'00r$!!$!
• Computers ma# be added or remoed wit&no impact on t&e network con0%uration andno concerns about address conict.
• Users on een t&e smallest networks bene0tas t&e# do not need to know &ow tocon0%ure a 'C()*( control panel.
• " computer on suc& a network is said to&ae ' 0&'5#c IP '00r$!!.
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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