Networking Basics

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Networking Basics

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Unicast

Unicast is One to One communication

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Multicast

Multicast is One to Group Communication

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Broadcast

Broadcast is One to All Communication

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Topology A topology is a description of any kind of locality in

terms of its layout. In communication networks, a topology is a usually schematic description of the arrangement of a network, including its nodes and connecting lines

The physical topology of a network describes the layout of the cables and workstations and the location of all network components

Common Topology:

Bus, Ring, Star and Mesh

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Bus Topology In a bus topology, all computers are attached to a single

continuous cable that is terminated at both ends, which is the simplest way to create a physical network

Terminator

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Star Topology Unlike those in a bus topology, each

computer in a star topology is connected to a central point by a separate cable. The central point is a device known as a hub

Although this setup uses more cable than a bus, a star topology is much more fault tolerant than a bus topology. This means that if a failure occurs along one of the cables connecting to the hub, only that portion of the network is affected, not the entire network. It also means that you can add new stations just by running a single new cable

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Ring Topology

In the ring topology, each computer is connected directly to two other computers in the network. Data moves down a one-way path from one computer to another i.e. clock wise

Laying out cable in a ring is that the cable design is simple. The bad news is that, as with bus topology, any break, such as adding or removing a computer, disrupts the entire network. Also, because you have to “break” the ring in order to add another station, it is very difficult to reconfigure without bringing down the whole network

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Ring Topology

Note: Even though all computers are connected through a single cable, if there is a break all the computer connected to the ring topology will not work

Example: If Machine A Wants to talk to Machine D The data can travel only Clock Wise If there is a break in the loop the data cannot be transferred

A

B

C

D

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Mesh Topology In a mesh topology, a path exists from

each station to every other station in the network. While not usually seen in LANs, a variation on this type of topology—the hybrid mesh—is used on the Internet and other WANs in a limited fashion.

Hybrid mesh topology networks can have multiple connections between some locations, but this is done only for redundancy.

Also, it is not a true mesh because there is not a connection between each and every node, just a few for backup purposes

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Coaxial Cable Coaxial cable consists of a

central copper core surrounded by an insulator, a braided metal shielding, called braiding, and an outer cover, called the sheath or jacket

EG : Cable TV network and Cable Modem use the coaxial cable

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Coaxial Cable Connector

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Thicknet (10Base5) Thicknet cabling, also called thick wire Ethernet, is a rigid coaxial

cable approximately 1-cm thick used for the original Ethernet networks.Thicknet is also called “yellow Ethernet” or “yellow garden hose.”

IEEE designates Thicknet as 10Base5 Ethernet.The “10” represents its throughput of 10 Mbps, the “Base” stands for baseband transmission, and the “5” represents the maximum segment length of a Thicknet cable, which is 500 m. You may find this on older networks.

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Thinnet (10base2) Thinnet, also known as thin Ethernet, was the most popular medium

for Ethernet LANs in the 1980s. Thinnet is rarely used on modern networks, although you may encounter it on networks installed in the 1980s or on newer small office or home office LANs

IEEE has designated Thinnet as 10Base2 Ethernet, with the “10” representing its data transmission rate of 10 Mbps, the “Base” representing the fact that it uses baseband transmission, and the “2” representing its maximum segment length of 185 (or roughly 200) m.

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Twisted Pair (TP) Twisted-pair (TP) cable is

similar to telephone wiring and consists of color-coded pairs of insulated copper wires. The more twists per inch in a pair of wires, the more resistant the pair will be to all forms of noise.

Higher-quality, more expensive twisted-pair cable contains more twists per foot. The number of twists per meter or foot is known as the twist ratio.

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Twisted Pair (TP)

Twisted-pair cable is the most common form of cabling found on LANs today. It’s inexpensive, flexible, and easy to install, and it can span a significant distance before requiring a repeater (though not as far as coax). Twisted-pair cable easily accommodates several different topologies, although it is most often implemented in star or star-hybrid topologies

One drawback to twisted-pair is that, because of its flexibility, it is more prone to physical damage than coaxial cable. All twisted-pair cable falls into one of two categories: shielded twisted-pair (STP) or unshielded twisted-pair (UTP).

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Shielded Twisted-Pair (STP) As the name implies, shielded twisted-pair (STP) cable consists of

twisted wire pairs that are not only individually insulated, but also surrounded by a shielding made of a metallic substance such as foil. Some STP use a braided metal shielding. The shielding acts as a barrier to external electromagnetic forces, thus preventing them from affecting the signals traveling over the wire inside the shielding. The shielding may be grounded to enhance its protective effect.

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Unshielded Twisted-Pair (UTP)

Unshielded twisted-pair (UTP) cabling consists of one or more insulated wire pairs encased in a plastic sheath. As its name implies, UTP does not contain additional shielding for the twisted pairs. As a result, UTP is both less expensive and less resistant to noise than STP

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UTP Types

UTP CAT 1/2/3/4/5/6Cat 1 Data Rate upto 1 Mbps – Telephone Line

Cat 2 Date Rage upto 4 Mbps – Token Ring

Cat 3 Data Rate upto 10 Mbps – Token Ring & 10 Base – T

Cat 4 Data Rate upto 16 Mbps – Token Ring

Cat 5 Date Rate up to 100 Mbps Ethernet – 16 for Token Ring

Cat 5e Data Rage upto 1000 Mbps Ethernet

Cat 6 Data Rate upto 1000 Mbps Ethernet

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Fiber Optic

A fiber-optic system is similar to the copper wire system that fiber-optics is replacing. The difference is that fiber-optics use light pulses to transmit information down fiber lines instead of using electronic pulses to transmit information down copper lines.

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Fiber Optic Bandwidth Up to 100s of

Gbps

Distance (100 +KM)

Three Types

– Single Mode

– Multi Mode

– Plastic Optical Fiber Mode

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Straight Through Cable

Pin Number Wire color Wire Becomes Pin number Wire color

Pin 1 Orange / White Pin 2 Orange Pin 3 Green / White

Pin 4 Blue Pin 5 Blue/White Pin 6 Green Pin 7 Brown/White

Pin 8 Brown

1 1

2 2

3 3

6 6

Pin 1 Orange / White Pin 2 Orange Pin 3 Green / White


Pin 8 Brown

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Straight Through Cable In a UTP implementation of a straight-through cable,

the wires on both cable ends are in the same order

You can determine that the wiring is a straight-through cable by holding both ends of the UTP cable side by side and seeing that the order of the wires on both ends is identical

You can use a straight-through cable for dissimilar devices

Connecting a router to a hub or switch Connecting a server to a hub or switch Connecting workstations to a hub or switch

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Cross Over Cable

Pin Number Wire color Wire Becomes Pin number Wire color

Pin 1 Orange/White Pin 2 Orange Pin 3 Green / White


Pin 8 Brown

1 3

2 6

3 1

6 2

Pin 1 Green/White Pin 2 Green Pin 3 Orange/White

Pin 4 Blue Pin 5 Blue/White Pin 6 Orange Pin 7 Brown/White

Pin 8 Brown

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Straight through / X- Over Cable

The Transmit and Receive pins are shown above

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Cross Over Cable In the implementation of a crossover, the wires on each end of the cable are crossed

Transmit to Receive and Receive to Transmit on each side, for both tip and ring

Notice that pin 1 on one side connects to pin 3 on the other side, and pin 2 connects to pin 6 on the opposite end

You can use a crossover cable for similar devices

Connecting uplinks between switches Connecting hubs to switches Connecting a hub to another hub.

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Where to use Straight through and Cross Over Cable

Similar Devices

Cross Over Cable

Dissimilar Devices

Straight through CableHub / Switch PC

PCPC

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Registered Jack (RJ)

RJ-11 – Defined for telephone connectors

RJ-45 – Defined for UTP connectors

RJ 45RJ 11

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Local Area Network (LAN) A computer network that spans a relatively small area. Most

LANs are confined to a single building or group of buildings

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Wide Area Network (WAN) A computer network that spans a relatively large geographical

area. Typically, a WAN consists of two or more local-area networks (LANs)

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Intranet

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Internet

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Open System Internetconnect (OSI) The OSI model was designed to promote

interoperability by creating a guideline for network data transmission between computers that have different hardware vendors, software, operating systems, and protocols

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OSI The OSI reference model illustrates the networking process

as being divided into seven layers. This theoretical construct makes it easier to learn and understand the concepts involved. At the top of the model is the application that requires access to a resource on the network, and at the bottom is the network medium itself

As data moves down through the layers of the model, the various protocols operating there prepare and package it for transmission over the network. Once the data arrives at its destination, it moves up through the layers on the receiving system, where the same protocols perform the same process in reverse

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OSI

OSI developed by International Organization for Standardization (ISO) in 1974

It consists of Seven LayersEach layer has specific

processing function

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Open System Interconnect

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Data communication with OSI

How data travels through the layers of the OSI model

Peer Communication

Information flow

Network Medium

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OSI

In Physical Layer data will be converted into Binary (0’s & 1’&)

It transmits raw bit stream over physical cable

The Physical layer defines all the electrical and physical specifications for devices

Physical Layer defines techniques to transfer bit stream to cable Hub and Repeater works in Physical Layer

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OSI Data Link Layer handles data frames between the Network and Physical layers

It Receives end packages raw data from the Physical layer into data frames for delivery to the Network layer as packets

Error detection is happening in this layer

Data link Layer is divided in to two layers: LLC (Logical Link Control) and MAC ( Media Access Control)

Switch, Bridge and Network Interface card works in Data Link Layer

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OSI

Network Layer is responsible for providing best path for data to reach the destination

Logical addressing is happening in this layer

Network Layer translates logical network address and names to their physical address (e.g. computer name = MAC address)

Router works in Network Layer

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OSI

Transport Layer is responsible for reliable delivery of data. It is also known as the heart of OSI layers

Provides error-checking to guarantee error-free data delivery, with on losses or duplications

Provides acknowledgment of successful transmissions; requests retransmission if some packets don’t arrive error-free

The major function of the Transport Layer is Error Correction

Identifying Service, Multiplexing & De-multiplexing and Segmentation are happening in this layer Brouter and Gateway works in Transport Layer

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Breaking data in to Segments

Data

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OSI Session Layer is responsible for establishing, maintaining and terminating session

Responsible for name recognition (identification) so only the designated parties can participate in the session

Manages who can transmit data at a certain time and for how long

Provides synchronization services by planning check points in the data stream if session fails, only data after the most recent checkpoint need be transmitted

Gateway works in Session Layer

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OSI Presentation layer is responsible for presenting the data in a standard format and data translation (formatting)

The Presentation layer relieves the Application layer of concern regarding syntactical differences in a message's data representation within the end-user systems

Following tasks are performed in Presentation Layer:

Encoding – DecodingEncryption – Decryption Compression – Decompression

Gateway Works in Presentation Layer

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OSI

Application Layer provides the operating system with direct access to network services

Application layer provides an interface so that processes such as Excel or Word that are running on the local machine can get access to network services (E.G., retrieving a file from a network server)

Handles network access, flow control and error recovery

It serves as the interface between the user and the network

It’s a user specific layer

Gateway works in Application layer

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OSI

HUB

Switch

Router

Gateway

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OSI

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OSI

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IP Addressing Internet Protocol Address is given to the computer as an

identifier to a computer in a TCP/IP Network

IP Address is also known as Logical Address

IP Address works in Layer 3 (Network)

• Two versions of IP Addressing

• IP Version 4 - 32 bit address (Currently we are using)

• IP Version 6 - 128 bit address

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IP Addressing IP Address is divided in to Network Portion and

Host Portion

• Class A is written as N.H.H.H

• Class B is written as N.N.H.H

• Class C is written as N.N.N.H

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IP Addressing

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IP Address

• Class A 1 - 126

• Class B 128 - 191

• Class C 192 - 223

• Class D 224 - 239

• Class E 240 - 254

Widely Used

Multicast

Research & Development

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IP AddressingClass First Bits First Byte

ValuesNetwork ID Bits Host ID Bits Number of

NetworksNumber of

Hosts

A

B

C

0

10

110

1 - 126

128 -191

192 - 223

8

16

24

24

16

8

126

16,384

2,097,152

16,77,214

65,534

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Class Network Address

A 10.0.0.0 through 10.255.255.255

B 172.16.0.0 through 172.31.255.255

C 192.168.0.0 through 192.168.255.255

Private IP Address Range

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IP Addressing Loop Back Address:

The IP address 127.0.0.1 is used as the loop back address. This means that it is used by the host computer to send a message back to itself. It is commonly used for troubleshooting and network testing

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IP Addressing Loop Back address is also known as semi broad cast address Range of Loop back address : 127.0.0.1 to 127.255.255.254 Any IP address starts with 127 is known as loop back address

Click Start Run Type cmd Ping 127.56.26.36

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Subnet Mask

Class Default Subnet Mask

Class A is written as 255.0.0.0 N.H.H.H

Class B is written as 255.255.0.0 N.N.H.H

Class C is written as 255.255.255.0 N.N.N.H

Subnet Mask is to differentiate the Network ID and Host ID

Two numbers reserved for Subnet Mask i.e. 0 & 255

0 Denotes Host and 255 Denotes Network

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Subnet Mask IP Address : 10.20.50.26 Subnet Mask : 255.0.0.0

For this IP Address :

Network ID is : 10.0.0.0

First Valid IP Address : 10.0.0.1

Last Valid IP Address : 10.255.255.254

Broad Cast Address : 10.255.255.255

Number of hosts = (256x256x256) -2

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Number of hosts = (256x256) – 2

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Number of hosts = (256) – 2

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Subnet Mask IP Address 172.26.28.36 Subnet Mask : 255.0.0.0

For this IP Address:






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Subnet Mask IP Address 172.26.28.36 Subnet Mask : 255.255.0.0







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Subnet Mask IP Address 172.26.28.36 Subnet Mask 255.255.255.0







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Subnet Mask







IP Address 192.168.0.152 Subnet Mask 255.255.255.0

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Broadcast Address

Messages that are intended for all computers on a network are sent as broadcasts

These messages always use the IP address 255.255.255.255

Any IP Address with last Octet as 255 is known as broadcast address for that particular network E.g.: 10.255.255.255

The IP address of 0.0.0.0 is used for the default network

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How to assign static IP address and Subnet Mask

High light Local Area Connection Right Click Select Properties

Select Internet Protocol (TCP/IP) and select “Properties”

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How to assign static IP address and Subnet Mask

When ever you assign a Static IP Address it’s Mandatory to assign static DNS

For Windows 2000 and above Subnet Mask will be automatically assigned by the computer with the help of Network ID

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Mac Address

The Media Access Control address (MAC) can be equated to the serial number of the NIC. Every IP packet is sent out of your NIC wrapped inside an Ethernet frame which uses MAC addresses to direct traffic on your locally attached network

MAC addresses therefore only have significance on the locally attached network. As the packet hops across the Internet, its source/destination IP address stays the same, but the MAC addresses are reassigned by each router on the way using a process called ARP

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Mac Address MAC addresses are usually written in one

of the following two formats:

00:13:21:0F:83:DF 00-13-21-0F-83-DF

Mac address is a 48 bit address

Mac address are 12 digit Hexadecimal {0-9} {A- F} Address

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MAC Address

The First Octet of the MAC Address is known as Group Unique 00 : 13 : 21 : 0F : 83 : DF

The Second and Third Octet of the MAC Address is known as Organization Unique Identifier (OUI) 00 : 13 : 21 : 0F : 83 : DF

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MAC Address

Any Mac address starts with 00 is known as Unicast address 00 : 13 : 21 : 0F : 83 : DF

Any Mac address starts with 01 is known as Multicast 01 : 13 : 21 : 0F : 83 : DF

Any Mac address starts with FF is known as Broadcast FF : 13 : 21 : 0F : 83 : DF

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MAC Address

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Request Timed Out The ping command timed out because there was no reply from the

host. The source and the destination computer are in the same network

When Ping command is initiated from one system to the other in a network if the firewall is enabled on the Destination System Request Timed Out error will Pop up

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Destination Host Unreachable

The host that you are trying to ping is in a different network. Destination and the source belong to the different network

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Difference between Request timed out and Destination Host Unreachable

IP : 192.168.1.53Mask : 255.255.255.0D.G : 192.168.1.1

IP : 192.168.0.8Mask : 255.255.255.0D.G : 192.168.0.1

IP : 192.168.2.56Mask : 255.255.255.0

IP : 192.168.1.36Mask : 255.255.255.0

Hub/Switch

Hub/Switch

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Difference between Destination Host Unreachable and

Destination Host Net Unreachable

Cable/DSL Modem

WAN Side

LAN Side

Internet

Note: Since the Router is not able to pass the WAN interface it is giving the reply from LAN interface

IP : 192.168.2.168Mask : 255.255.255.0

IP : 192.168.1.192Mask : 255.255.255.0

Hub/Switch

Router

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Destination Net Unreachable

Destination Net Unreachable message is one which a user would usually get from the Default Gateway when it doesn't know how to get to a particular net work

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Unknown Host If the DNS resolution is not happening the computer will display as

“Unknown host”

Global DNS has to be assigned to fix this issue

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Command Prompt Error If the static IP Address is assigned to the computer and if we

tried to renew the IP Address it will display as “Operation failed as no adapter is in the state permissible for this operation

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Error Code 28 (Command Prompt

Direct Firewall or PIX or Norton Internet Security Installed (NIS)

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Error Code 65 (Command Prompt

Anti Spy Ware or Zone Alarm in the Computer

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Socket Error

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Digital Signature Digital signatures are especially important for electronic commerce

and are a key component of most authentication schemes. To be effective, digital signatures must be unforgeable

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Digital Signature A digital certificate contains the digital signature of the

certificate-issuing authority so that anyone can verify that the certificate is real

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NIC Card Installation

Physically install the network adapter, and then restart the PC.

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NIC Card Installation If the Operating System is Windows 2000 and above the screen will display as New Hardware Found and select “Next”

Select the “Hardware Type”

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SMC 1211 TX

Select “Display a List” Select the “Manufacturer”

and Click “Have Disk”

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Select “Browse” Select the Location as CD-Rom Select “Browse”

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Select the “Drivers” Select the “File” and Click “OK”

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Click “OK”

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Click “Yes” to restart the computer

Check the Device Manager for Device Status

Networking Basics

Technology

coaxial cable coaxial

thicknet cable

pair tp cable

twistedpair stp cable

single cable

bus topology

expensive twistedpair

star topology