·TCP - performs packetizing: breaking the data into smaller packets, numbering them, ensuring each packet is reliably delivered, and putting them into the proper order at the destination. TCP is only active at the sender and receiver.
·IP - performs routing and addressing.
ii)
Server Side Code
Client Side Code
Programming Language:
·PHP
·ASP.Net in C#, C++, or Visual Basic.
Programming Language:
·DHTML
·JavaScript
Software that runs on the server, not the client
Software that is downloaded from Web server to browser and then executes on the client
·Process user input.
·Display pages.
·Make interactive webpages.
·Make stuff happen dynamically on the web page.
iii)
Internet : The Internet is a network that is available to anyone with an
Internet-connected device. It is a massive collection of networks sharing
information publicly in the form of interlinked Web pages. Internet Protocol
defines a site's unique location which most users see as a domain name or URL.
The network is literally world-wide and is often referred to as the world wide
web.
Extranet : An extranet is similar to an intranet, but is accessible via
a Web portal. An extranet may be accessed from anywhere if the user has a valid
user name and password. The purpose of this type of network is to allow
collaboration and sharing of resources not only in-house but with a select
group of outside users. For instance, businesses will use an extranet to allow
customers to log in to provide input on projects. Another example is using a
virtual private network to allow employees to log in to the network when
they're are not in the office.
Intranet : An intranet network is only available to a small group of
people. Intranets are mainly used within businesses and organizations to
provide access to files and applications among networked computers and servers.
Intranets may or may not have access to the Internet. If an intranet does
connect to the Internet, a firewall is used to prevent outside access to the
intranet. The purpose is to allow people within the same company to share
information over a local area network. It is sometimes referred to as a private
Internet.
Websites come in a variety of different shapes and sizes but one way they can be divided is between static sites and dynamic sites.
The difference is not obvious when you’re just looking at a website in your browser, but it can make a big difference in the function of your website.
Static Web Sites
Static Web pages display the exact same information whenever anyone visits it. Static Web pages do not have to be simple plain text. They can feature detailed multimedia design and even videos. However, every visitor to that page will be greeted by the exact same text, multimedia design or video every time he visits the page until you alter that page's source code.
Advantages of Static Web Sites
Flexibility is the main advantage of a static site - every page can be different if desired, to match the layout to different content, and the designer is free to put in any special effects that a client may ask for in a unique way on different pages. This allows theming - for instance an author may want a different theme for a different book and associated pages or perhaps for a series of books, in order to match the cover designs or the context of the stories.
Disadvantages of Static Web Sites
The main problem with any static web site appears when you wish to update the content. Unless you are conversant with HTML and the design methods used in the site then you have to go back to the designer to have any content changes made. This may be perfectly fine when a new page is required which needs design input, but if all you want to do is change some text then it can be a nuisance for both client and designer.
The second main problem is scalability. If you wish to sell products on your site and you have a lot of them then you may have to construct individual pages for each one, which can take considerable time, effort and cost.
Dynamic Web Sites
Dynamic pages can serve a variety of purposes. For example, websites run by content management systems allow a single source code file to load the content of many different possible pages. Content creators use a gateway page to submit the material for new pages into the Content Management System database. The dynamic page can then load the material for any page in the database, based on parameters in the URL with which a visitor requests the page. Dynamic pages are also what let users log into websites to see personalised content.
Advantages of Dynamic Web Sites
The main advantages of dynamic sites are that by connecting them to databases you can easily pull in information in an organised and structured way to create product pages or categories of related products sorted in a variety of different ways depending on how the user wants to view them.
This ability to connect to a database means that you can also create a content management system - an interface which allows the client to input and manage data via a web-based series of administration pages. That content can be text for their pages and images to go along with the text, or items in their product range with categories, specifications, short and long descriptions, images. In both these cases it can be as simple or as complex as the client requires.
Disadvantage of Dynamic Web Sites
The design of a dynamic site is more fixed than a static one because many of the pages are essentially a template into which data and content is poured to create multiple pages of a similar type. So for instance all your product pages will be essentially the same page layout with different data being displayed. While some customisation capability can be built in it is usually quite limited, such as selecting from a set of pre-defined options. Individual layout changes to particular pages are not usually possible.
There are thirteen type of website. All publicly
accessible websites collectively constitute the World Wide Web.
i)Portal
A web portal is most often one specially designed Web
page that brings information together from diverse sources in a uniform way.
Usually, each information source gets its dedicated area on the page for
displaying information
ii)News
A news website contains interesting material
including stories and articles relating to news, money, sports, life and time.
iii)Informational
An Informational Web Page is one whose purpose is to
present factual information. The URL Address frequently ends in .edu or .gov,
as many of these pages are sponsored by educational institutions or government
agencies.
iv)Business or Marketing
A business or marketing website contains content that
promotes or sells products or services. Almost every company has a website of
business or marketing.Many companies also allow you to purchase their products
or services online.
v)Blog
Is an informal Web site consisting of timestamp, or post
articles, a diary or journal format, usually listed in reverse chronological
order.
vi)Wiki
A wiki is a collaborative web site that allows
users to create, add, edit, or delete the contents of a web site using their
web browser. Many wikis are open to modification by the general public.
vii)Online Social Network
An online social network, also called a social networking
web site, is a site that encourages members to his online community to share
their interests, ideas, stories, photos, music, and videos with other
registered users. Most include chat rooms, newsgroups, and other communications
services.
viii)Educational
An educational website offers exciting avenues,
stimulating teaching and formal and informal learning. On the Web, you can
learn how to fly planes or how to cook a meal. For a more structured learning
experience, companies provide online training for employees.
ix)Entertainment
An entertainment site offers an interactive and
engaging environment. Popular entertainment sites offer music, video, sports,
games, web episodes, sweepstakes, chat room and more.
x)Advocacy
An advocacy site contains content that
describes a cause, opinion or idea. These websites usually have views of a
particular group or association.
xi)Web Application
A website that allows users to access and interact with
the software through a web browser on any computer or device that connected to
the Internet.
xii)Content Aggregator
An aggregator of content is a business that collects and
organizes and distributes web content or feeds, content to the Subscriber free
of charge or on payment.
xiii)Personal
A family often not associated with any organization or
private individual can maintain apersonal site or a single Web page.
(i) Hypertext Transfer Protocol (Http) and Hypertext Transfer Protocol Secure (Https)
HTTP and HTTPS: What do they do, and how are they different?
Hypertext Transfer Protocol (HTTP) is a protocol used in networking. When you type any web address in your web browser, your browser acts as a client, and the computer having the requested information acts as a server. When client requests for any information from the server, it uses HTTP protocol to do so. The server responds back to the client after the request completes. The response comes in the form of web page which you see just after typing the web address and press “Enter”.
Hypertext Transfer Protocol Secure (HTTPS) is a combination of two different protocols. It is more secure way to access the web. It is combination of Hypertext Transfer Protocol (HTTPS) and SSL/TLS protocol. It is more secure way to sending request to server from a client, also the communication is purely encrypted which means no one can know what you are looking for. This kind of communication is used for accessing those websites where security is required. Banking websites, payment gateway, emails, and corporate sector websites are some great examples where HTTPS protocols are used.
For HTTPS connection, public key trusted and signed certificate is required for the server. These certificate comes either free or it costs few dollars depends on the signing authority. There is one other method for distributing certificates. Site admin creates certificates and loads in the browser of users. Now when user requests information to the web server, his identity can be verified easily.
Here are some major differences between HTTP and HTTPS:
HTTP
HTTPS
URL begins with
“http://”
URL begins with
“https://”
It uses port 80 for
communication
It uses port 443
for communication
Unsecured
Secured
Operates at
Application Layer
Operates at
Transport Layer
No encryption
Encryption is
present
No certificates
required
Certificates
required
(ii) The Operation of Packet-Switched Network
Packet-switched describes the type of network in which relatively small units of data called packets are routed through a network based on the destination address contained within each packet. Breaking communication down into packets allows the same data path to be shared among many users in the network. This type of communication between sender and receiver is known as connectionless (rather than dedicated). Most traffic over the Internet uses packet switching and the Internet is basically a connectionless network.
How does packet switching work?
Imagine that you have a data file, perhaps an email or a document which is 2 Megabytes in size. You want to send this file to someone in another country.
When you send the file, it isn’t sent as one document (remember the telephone call), instead it is broken up into lots of small 'data packets'. Our 2MB file would be broken up into chunks of 512 bytes in size.
Before each packet is sent, it is given a 'header' containing the network IP address that it needs to arrive at and also details of the IP address from which it was sent. The header also gives each packet a number and records how many packets the data was split up into.
How do the packets get through the network?
Now comes the clever bit. Try to imagine the Internet as billions of computers all connected together in a huge mesh. There isn’t just one way to get from one computer to another, there are literally millions of different routes which can be taken.
So, the packets leave your computer and are sent through the network, knowing where they need to get to. The packets start to head off in different directions taking the least busy path at that instant. A machine called a 'Router' works out which is the next fastest connection and sends each packet on its way. During the course of its journey, a packet will travel through many routers, possibly in many different countries.
This method works extremely well, because if one branch gets too busy or broken, then the packets are automatically routed through another path instead.
What happens when the packets arrive?
When the packets arrive at their destination, they are put back together again in the right order. Remember earlier on we told you that each packet was given a number? This makes it possible to correctly reorder them. The header also contained a record of the number of packets into which the file was split. So, if any packets fail to arrive within a certain length of time then a message is sent back to the original computer asking for a replacement packet.
What happens to lost packets?
Sometimes packets can get lost and keep bouncing around from router to router, never quite getting to their destination.
A system had to be developed to deal with this because eventually the network would choke with these 'lost' packets. So to solve this problem a 'hop' count is also added to the packet header. Each packet is allowed to 'hop' from one router to another a maximum of say 100 times. Each time the packet passes through a router the ‘hop number’ is decreased by one. If the packet hasn’t arrived at its destination within the number of ‘hops’ allowed then it is deleted by the next router.
Advantages of Packet Switching
It makes very efficient use of the network - no tied-up lines.
It can easily get around broken bits of the network.
As customers increase, the network only has to expand slowly compared to circuit switching.
Disadvantages of Packet Switching
The time it takes to put back the data package changes each time, which can be a problem for time-critical information such as an emergency signal. The fancy name is for this is 'latency'.
Not very good for small data packages - for example if the data package itself is only 600 bytes long, then two packets of 512 bytes need to be used, plus the address information.
(iii) Differences of cellular transmission General Packet Radio Service (GPRS) and 4G
General Packet Radio Service (GPRS)
One step up from no data signal at all is GPRS, which stands for General Packet Radio Service. Wikipedia defines GPRS as a “best effort” service and “a packet oriented mobile data service on the 2G and 3G cellular communication system's global system for mobile communications (GSM).”
Depending on who you believe in 2G systems GPRS provides data rates of 35–171Kilobits per second (Kbps). 2G cellular technology combined with GPRS is sometimes described as 2.5G. It provides slow-speed data transfer, by using unused time division multiple access (TDMA) channels in, for example, the GSM system.
All you need to know is that GPRS means you might eventually get a webpage to load or an email or iMessage to send, but it will probably take longer than you have patience for.
4G (LTE)
4th generation network called LTE (Long Term Evolution), works in a very different manner than 2nd and 3rd generations. Shared access is done by OFDMA - the available channel is divided into subchannels (also called subcarriers) and each of them is treated separately; groups of those subcarriers are assigned to different mobile phones. Also LTE is designed as a data-only network so all of the traffic is IP-based and there are no more circuit-switched connections. In fact unless the operator has VoLTE service (Voice over LTE), your 4G connection will only handle sending data, and to make/receive a voice call your phone will have to fall back to a 2G or 3G network. Of course the data speeds will be quite higher, you can expect tens of Mbps.
The Main Difference Between General Packet Radio Service (GPRS) & 4G(LTE)
One limitation of GPRS
Speed - Most GPRS connections run slower than 56K connections on a computer because of the limitations of the GPRS technology. Although certain enhancements exist that help raise the bar, the speed does not compare to using a wired network connection or an alternative mobile Internet connection.
There are two basic categories of network topologies: Physical topologies and logical topologies.
The cabling layout used to link devices is the physical topology of the network. This refers to the layout of cabling, the locations of nodes, and the interconnections between the nodes and the cabling. The physical topology of a network is determined by the capabilities of the network access devices and media, the level of control or fault tolerance desired, and the cost associated with cabling or telecommunications circuits.
The logical topology in contrast, is the way that the signals act on the network media, or the way that the data passes through the network from one device to the next without regard to the physical interconnection of the devices. A network's logical topology is not necessarily the same as its physical topology.
Today’s network designs are based on three topologies:
1. Bus topology consists of series of computers connected along a single cable segment.
Single cable connects all network nodes without intervening connectivity devices
Devices share responsibility for getting data from one point to another
Terminators stop signals after reaching end of wire
Prevent signal bounce
Inexpensive, not very scalable
Difficult to troubleshoot, not fault-tolerant
This is refer as peer-to-peer networking
2. Ring topology connects computers to form a loop.
In Ring topology each node is connected to the two nearest nodes so the entire network forms a circle
Data only travels in one direction on a Ring network
Token passing is the method sending data around a ring.
A small packet, called token, passes around the ring to each computer in turn.
If the computer has information to send, its modifies the token, add address information and the data, and sends it around the ring.
That information travels around the ring until it either reaches its destination or return to the sender.
When the destination computer receives the information, it returns a massage to the sender for acknowledgement.
3. Star topology connects computers via central connection point or hub.
In a Star topology every node is connected through a central device such as a Hub or Switch
When a computer sends a signal, the hub receives and retransmits to all the computers or devices attached to that hub
All the connected computers will check the destination address, but only the computer to which the data is addressed processes that data
One major drawback about this topology is central point of failure. If the hub fails, all other computers and devices attached to that hub lose network access
However, if one of the computer and cable fails, it has no effect on the rest of the network
