Networking

What is a Network ?

A network consists of two or more computers that are linked in order to share resources.

Local Area Network (LAN)

A Local Area Network (LAN) is a network that is confined to a relatively small area. It is generally limited to a geographic area such as a writing lab, school, or building.

Wide Area Network (WAN)

Wide Area Networks (WANs) connect networks in larger geographic areas, such as Florida, the United States, or the world. Dedicated transoceanic cabling or satellite uplinks may be used to connect this type of global network.

IP ADDRESSES

 IP-networking protocol are 32-bit numbers. Every machine must be assigned a number unique to the networking environment. If you are running a local network that does not have TCP/IP traffic with other networks, you may assign these numbers according to your personal preferences. However, for sites on the Internet, numbers are assigned by a central authority, the Network Information Center.

Depending on the size of the network, the host part may need to be smaller or larger. To accommodate different needs, there are several classes of networks, defining different splits of IP-addresses.

 Class A :  Class A comprises networks  1.0.0.0  through  127.0.0.0.   The
                network number is contained in the first octet.  This provides
                for a 24 bit host part, allowing roughly 1.6 million hosts.

        Class B :  Class B contains networks 128.0.0.0 through  191.255.0.0;  the
                network  number  is  in the first two octets.  This allows for
                16320 nets with 65024 hosts each.

        Class C : Class C networks range from 192.0.0.0  through  223.255.255.0,
                with  the  network  number  being contained in the first three
                octets. This allows for nearly 2 million networks with  up  to
                254 hosts.

      Classes D, E, and F :  Addresses   falling  into  the  range  of  224.0.0.0
                through 254.0.0.0 are either experimental, or are reserved for
                future use and don't specify any network.

GATEWAY
A gateway is a network point that acts as an entrance to another network.
On the Internet, a node or stopping point can be either a gateway node or a host (end-point) node.
Both the computers of Internet users and the computers that serve pages to users are host nodes.

FIREWALL 
What is Firewall
A firewall is a security device that can be a software program or a dedicated network appliance.
The main purpose of a firewall is to separate a secure area from a less secure area
and to control communications between the two

VPN 
What is VPN ?
A virtual private network (VPN) protects your data and identity over public networks,
 like the Internet and wireless hotspots.

Why Use VPN ?
Most VPN's are used to add security.

VPN services provide different gateway cities where the IP address assigned to your computer is located.
This allows users to access websites only available to users from a certain country.
This application is particularly important for travelers who need to access websites from their home country
and for people living in regions rife with censorship, like USA and India
Network Diagram

Cable crumbing

straigt-through Cable Pinout for …. orange/white>orange, green/white>blue, blue/white>green, brown/white>brown,

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SINGLE MODE VS MULTIMODE

http://www.luxlink.com/faq/multi_or_single.htmko
http://www.sitech-bitdriver.com/tech/t2.htm
http://www.blurtit.com/q664141.html

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Network Monitoring Tools

DUMeter

Networx

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