Overview of the Internet

Advantages and Disadvantages of Internet, Intranet, Extranet

INTERNET

A worldwide collection of networks that links millions of business, government, educational and individuals.

advantages
-can freely download software
-can do online services
-can sent messages
-can find any information
disadvantage
-virus threats that mean your computer exposed to virus attacks-children expose to the pornographic sites-your information can be accessed by hacker


INTRANET

An intranet is an internal network that uses internet technologies. network which only available inside an organization or a company

advantages- commercial or confidential data kept secure within the organization.-email remain private and may also be encrypted-high bandwidth, no limit connection-reliable.

Differents types of Internet Connection, ISP, and Internet Address

Types internet connection:

• Dial-up connection                                                                   
• Broadband internet connection/direct connection

Dial-up connection   

1. Conventional dial-up

PC has to dial via phone line to connect to the internet.

it slower but cheaper and ties up to the phone lines and it was secure from hackers

example: TMNet

Advantages

-secure from hackers because not continually connected

 to the internet.

-include inexpensive hardware

-easy to set up and use

Disadvantages

-Slow connection speed (max of 56Kbps)

-Inconvenience because you have to dial up your ISP every time you

 want check email

-telephone line will be tied up while accessing to the internet

2. ISDN

•     also transfer data over ordinary telephone lines but typically  
•       uses two phone lines to transfer data. it requires a special ISDN modem
•      ISDN is faster but pricey. it doesn't tie up phone line and used by businesses and                      individualy.

Broadband internet connection/direct connection

1. DSL (Digital Subscriber Line)

• Broadband delivered over telephone lines

• Must be less than 3 miles from a switching station

• Transmits over telephone lines but does not tie up the line

• Fast, direct Internet access via standard telephone line

• ADSL is one of the more popular types of DSLs

• Requires DSL modem

• Available in urban areas

• Half or less of cable speeds

• Example :- Streamyx without WiFi

2. Cable Internet Service/ Cable Modem

•   Cable modem: Most widely used home broadband connection

•   Provides high-speed Internet access through    the cable television network via a cable modem.

3.Fixed wireless

• Uses radio transmission towers rather than satellites

• Not available in all areas

• Expected to use WiMAX

• Provides high-speed Internet connections using a dish-shaped antenna to communicate via radio signals.

4. Wi-Fi ( Wireless Fidelity)

• Data is transmitted through radio waves

• Public wireless networks

• Both free and fee-based are available

• Currently Wi-Fi for short range, but WiMAX may soon be an option

• Provide high-speed Internet connections to compatible or properly equipped wireless computers and device.

• Example : Streamyx with WiFi

5. Satellite Internet service

• Broadband option for rural areas

• More expensive than cable or DSL

• Available in many areas other broadband options are not

• Provides high-speed Internet connections via satellite.

• A satellite dish communicates with a satellite modem.

                                        

6. Fiber to the Premises (FTTP)

• Also known as Broadband over Fiber (BoF)

• Delivers over fiber-optic cabling all the way to the building

• Available in limited areas

• Fast but expensive

• Uses fiber-optic cable

• Provide high-speed Internet access to house and business users.

7. Cellular Radio Network       

• Also known as Mobile wireless 

• Access via mobile phone or device

• Offers high-speed Internet connections to devices with built-in compatible technology or computers with wireless modems.

• Example provider:- Celcom, Maxis, DiGi

Internet Service Provider

An ISP (Internet service provider) is a company that provides individuals and other companies access to the Internet and other related services such as Web site building and virtual hosting. An ISP has the equipment and the telecommunication line access required to have a point-of-presence on the Internet for the geographic area served. The larger ISPs have their own high-speed leased lines so that they are less dependent on the telecommunication providers and can provide better service to their customers. Among the largest national and regional ISPs are AT&T WorldNet, IBM Global Network, MCI, Netcom, UUNet, and PSINet.

Access Provider

A business that provides individuals and organizations access to the Internet for free or for a fee

Responsibilities of an ISP

• Providing and maintaining a connection to the Internet

• Support the hardware and software needed to service that connection

• To protect their site and network from external threats such as viruses, hacker attacks and other illegal activities

• Provide 24-hour customer service and technical support

Example of ISP in Malaysia

ISP: TMNet

Products : Streamyx , UniFi, TM Hotspot

ISP : Time

Product : Time Fibre Home Broadband, Time Broadband

ISP: Packet One Network

Products : P1

ISP : YTL Communications

Product : YES

Internet Address

• A number that uniquely identifies each computer or device connected to the Internet.

• IP addresses are also referred to as IP numbers and Internet addresses.

• IP address sometimes is called a dotted decimal number or dotted quad.

Usage

• A way to find specific server or computer on the internet or a network

• Provide identity to a computer in a network

• Identify for a particular device/machine on a particular network

• Allows transfers of files and e-mail

Structure

• IP addresses usually consists of four groups of number each separated by a period.

• The number in each group is between 0 and 255.

• It is 32 bit long ,each group is 8 bits long

• Commonly written in decimal.

• Written, for example, 128.35.0.72

IP versions

Two versions of the Internet Protocol (IP) are in use:

•  IP Version 4 (IPv4) 
•  IP Version 6 (IPv6)

• IPv4 an address consists of 32 bits which limits the address space to 4294967296 (232) possible unique addresses.
• Version 4 of Internet Protocol,the most widely used version of IP
• Version 6 of Internet Protocol, has more capabilities than IPv4, including providing for far more IP address

Domain names and IP addresses

People prefer to use easy-to-remember names instead of IP addresses 

Domain names (a part of the URL) are alphanumeric names for IP addresses.

 e.g., neon.ece.utoronto.ca, www.google.com, ietf.org

The domain name system (DNS) is an Internet-wide distributed database that translates between domain names and  IP addresses

Top-level domains (TLDs)

The first-level set of domain names are the top-level domains (TLDs).

Three types of top-level domains:

• Organizational: 3-character code indicates the function of the organization
• Used primarily within the US 
• Examples: gov, mil, edu, org, com, net

Geographical: 2-character country or region code

Examples: us, va, jp, de

Reverse domains: A special domain (in-addr.arpa) used for IP address-to-name mapping

There are more than 200 top-level domains.

Generic Top-level domains (gTLD)

A generic top-level domain (gTLD) is one of the categories of top-level domains (TLDs) maintained by the Internet Assigned Numbers Authority (IANA) for use in the Domain Name System of the Internet.

Welcome

Network Topology

NETWORK TOPOLOGY
-a network topology refers to the layout of the computers and devices in a communications network.
-it refers to both the physical topology and logical topology layout of a network.

Physical Topology
-the physical layout of nodes,workstations and cables in the network.

Logical Topology
-the path that data travels between computers on a network.

Type of network topology
-BUS NETWORK TOPOLOGY
-STAR NETWORK TOPOLOGY
-RING NETWORK TOPOLOGY

1.BUS NETWORK TOPOLOGY

-a bus network consists of a single central cable (backbone), to which all computers and other devices connect.

-when sending device transmits data, the address of the receiving device is inclided with thye transmission.if the devices address does not match the intended address for the data, the device ignores the data.if the data does not match the device address,the data is accepted.
-all devices receive the data but only the receiving device accept them.

Advantages and Disadvantages of bus network topology

Advantages
-inexpensive and easy to install
-computers and other nodes can be attached and  detached at any
 point on the bus without disturbing the rest of network.
-failure of one node usually does not affect the rest of the bus network.

Disadvantages
-because all systems on the network connect to a single cable or backbone,
 a break in the cable will prevent all systems from accessing the network.
-it is difficult to identify the problem if the entire network shut down.

2.STAR NETWORK TOPOLOGY

-all the computers and devices (nodes) on the network connect to a central device,
 thus forming a star.

Advantages and Disadvantages of star network topology

Advantages
-if one nodes fails, only that node is affected
-nodes can be added to or removed from network with little or no disruption.
-easy to troubleshoot and isolate problem

Disadvantages
-if the hub or switch fails, the entire network will be inoperable
-requires more cable than most of the other topologies
-more expensive because of the cost of the hub/switch

3. RING NETWORK TOPOLOGY

- On a ring network, a cable forms a closed forms a closed loop (ring) with all computers and devices arranged along the ring.

Advantages and Disadvantages of ring network topology

Advantages

-Transmission of data is simple as packets travel in one direction only.

-cable faults are easily located, making troubleshooting easier

-all nodes in ring topology share the network resources fairly

Disadvantages

-a failure in any cable or nodes breaks the loop and can take down entire network

-data packets must pass through every computer, thus make it slower

-more difficult to install than a bus network

Differentiate between LAN, MAN, and WAN

BASIS OF COMPARISON	LAN	MAN	WAN
Expands to	Local Area Network	Metropolitan Area Network	Wide Area Network
Meaning	A network that connects a group of computers in a small geographical area.	It covers relatively large region such as cities, towns.	It spans large locality and connects countries together. Example Internet.
Ownership of Network	Private	Private or Public	Private or Public
Design and maintenance	Easy	Difficult	Difficult
Propagation Delay	Short	Moderate	Long
Speed	High	Moderate	Low
Fault Tolerance	More Tolerant	Less Tolerant	Less Tolerant
Congestion	Less	More	More
Used for	College, School, Hospital.	Small towns, City.	Country/Continent.