1. NETWORKING CONCEPTS
Networking Hardware

2. Transmission media
A medium of data transmission over a computer network is called a transmission medium.
It can be guided (wired)or unguided (wireless)

3. Wired media Twisted pair Cable UTP(Unshielded Twisted Pair)
STP(Shielded Twisted Pair)
Coaxial Cable
Optical Fibre Cable

4. Twisted pair
It is widely used to transfer data over computer networks. It contains four twisted pairs covered in an outer shield . They are colour coded .
These are more commonly used for connecting computers in small networks

6. shielded and Unshielded twisted pair cable

7. utp Low cost cable for small networks
Thin, diameter approx 0.43cm & flexible
Easy to install
Can carry data upto 100cm

8. stp
It offers better immunity against internal and external electromagnetic interferences
It is expensive than UTP
It is difficult to install

9. Co-axial cable

10. Co-axial cable
It consists of two conductors that share a common axis. The inner conductor is a straight wire and the outer conductor is a shield that might be braided or a foil

11. characteristics It can carry data for a distance (185m-500m)
Less susceptible to electromagnetic field
Bulkier and less flexible than twisted pair
Its thickness (1cm in diameter)
Difficult to install.

12. Optical fibre cable

13. opticle Fibre cable Optical fibres are long and thin
They are of the thickness of a human hair
Used to transmit data through light signals over long distances.
Core-It is the thin glass rod at the center through which the light travels
Cladding- It is the outer optical material surrounding the core that reflects the light back into the core
Buffer coating- It is the plastic coating that protects the cable from damage and moisture.

14. characteristics Not susceptible to electromagnetic fields
It can carry data for a very large distance
Not susceptible to electromagnetic fields
Specially skilled people are required to install it
Till date it is the most expensive and the most efficient cable available today for computer networks

15. Wireless media
Electromagnetic waves are used for wireless communication networks. Based on their frequencies the waves are categorized into various categories.
Radiowaves,microwaves,infrared radiation, visible light, ultraviolet ,X-rays and gamma rays.

17. radiowaves Frequency range 3 KHz to 3 GHz
Used for communication over a distance from few meters upto covering an entire city
These can penetrate through buildings easily
Used in cordless phones, AM(Amplitude modulation) and FM(Frequency Modulation) radio broadcast, garage door openers etc.

18. characteristics
Omni directional(generated in circular manner and spread all over)
Inexpensive than wired media
Offers ease of communication over difficult terrain
Transmission can be interfered by motors or electrical equipments
Less secured mode of transmission.

19. microwaves Frequency range of 300 MHz to 300 GHz
Travel in straight lines and cannot penetrate any solid object, thats why for long distances communication ,high towers are built and microwave antennas are put on their tops.

20. Characteristics Relatively inexpensive than microwave media
Transmission is in straight lines, antennas need to be properly aligned.

21. Infrared waves Frequency range of 300 GHz to 400 THz.
Used for short range communication approx. 5m eg: remote control device, cordless mouse and intrusion detectors
Cannot pass through solid objects or walls

22. characteristics
It has line of sight transmission, so at a time only two devices can communicate with each other.
Its performance drops with longer distances

23. Bluetooth
Bluetooth technology uses radiowaves for the short range of communication of approx 10m
CHARACTERISTICS
Line of sight is not required
It can connect upto eight devices together
Slow data transfer rate(1Mbps)

25. Satellite These links are used for very long distance
communication from intracity to intercontinental.
Transmission from earth to a satellite is known as uplink, and transmission from satellite to earth is downlink

26. characteristics Satellites cover large area of earth
This system is expensive

27. Network devices
NIC(Network Interface Card)

28. Network Interface Card
Any computer which is connected to computer network must have an NIC installed in it.
A computer communicates with other computer with the help of NIC only.

29. HUB

30. hub
A hub is an electronic device that connects several nodes to form a network and redirects the received information to all the connected nods in broadcast mode.
Each computers NIC is connected to hub. Whenever a computer wants to send some information to other computer,NIC sends that information to hub. Then the hub retransmits this information to other computers.The intended node accepts it and others reject it.

31. switch
A switch is an intelligent device that connects several nodes to form a network and redirects the received information only to the intended node.

32. repeater
It is a device that is used to regenerate a signal which is on its way through a communication channel.A repeater regenerates the received signal and re- transmits it to its destination.

33. gateway
A Gateway is a device ,which is used to connect different types of networks and perform the necessary translation so that the connected networks can communicate properly

34. Network topologies
Node: Any device which is directly or indirectly connected to a computer network is called a node.
A topology is an arrangement of physical connections among nodes in a network.
Types of topologies are
Bus Topology
Ring Topology
Star Topology
Tree Topology

35. Bus topology

36. characteristics More efficient than bus Easy to install
Easy to diagnose the fault
Failure of hub/switch leads to failure of the system
Requires more cable length than bus

37. bus

38. characteristics Easy to install Requires less cable length
Failure of node does not affect the network
If cable or terminator is at fault then the entire network stops working
Fault diagnosis is difficult
At a time only one node can transmit data.

39. Tree topology

40. characteristics Easy to expand the network
If one network fails, other network is successfully working

41. Network protocols
It is a set of rules for communication among networked devices. Protocols generally includes rules of how and when a device can send or receive the data, how is the sent data packaged and how it reaches its destination.
Types of protocols are:
HTTP
TCP/IP
PPP

42. http(hyper text transfer protocol)
It is used to transfer all files and other data from one computer to another on the world wide web. When http client(browser) sends a request to http server(web server)

43. Tcp/ip(transmission control protocol)
It is a basic protocol which is used by internet .It breaks into small packets and then it is reassembled at the receiving end.
PPP(point to point protocol)
It is a protocol for direct communication between two computers, It is direct communication between two computers.
It is used for serial cable, Trunk line, Phone line, cellular phone.

44. Types of networks
MAN
PAN
LAN
WAN

45. MAC ADDRESS AND IP ADDRESS
A MAC(Media Access Control) address is a unique 12 digit identifying manufacturer code(6 digits for manufacturer code and 6 digits for serial number) assigned to each NIC,MAC address of an NIC never changes.
An IP address is a unique 4 digit hexadecimal number assigned to each node on a network.IP address settings of a node can be changed by the user.

46. Domain name resolution
It is process of getting corresponding IP address from a domain name
URL format

47. Network security Denial of Service attacks:
Denial of access to information
Denial of access to Application
Denial of access to resources
Denial of access to a website

48. Snooping & evesdropping
Snooping is to gaining unauthorized access to another organization’s data.
Evesdropping refers to gaining unauthorized access another person’s or organization’s data while the data is on its way on the network

49. How to protect the network
login-password
Firewall
Anti Virus Software
File permissions
 Back up your files frequently. 
Update your operating system regularly