Information Technology(7th sem)

1.What is the difference between the internet, intranet, and extranet?

Intranet:

Intranet is a computer network system in which a specific organizational systems share information, computing services and operating systems with each other by using an Internet (IP )Technology. This term basically refers to the network of a specific organization. you can also says it a private network.Authenticated users of the organization can access the database system, search engines, directory and can distribute documents and workflow. Employees can makes interactive communication in shape of chatting, audio and videoconferencing, groupware and teleconferencing. The benefits of Intranet is that low development and maintenance cost arises on this setup. It is also a means of friendly environment and speedily sharing of secret information on time.

Extranet:

The term Extranet is linked with Intranet. Extranet is a kind of computer network that allows the outside users to access the Intranet of organization. This network system is basically used for business to business (B2B) purposes. This system basically allows the outside users of an organization, like partners, suppliers, vendors and other stakeholders to remain in touch with the activities of organization. Information and data access performed through a proper account or link system. This is a best network system to keep in touch with market position and share a large amount of data to partners in a timely manner. Moreover, conducting new training programs and discussing the products catalogs with partners can be easily done without bearing too much cost of travelling.

Following are the differences between Internet, Intranet and Extranet.

First difference between all is a matter of availability. Internet is a global network system and is available to all while Intranet and Extranet are available to limited inside and outside users of the organization.
'Intranet and Extranet are more secure than Internet because having Intranet or Extranet network system means organization has created a firewall against outsiders. Accessing any information on Internet is not much difficult today.

• General public is the user of Internet so it can be called as public network while business persons and organization are the users of Intranet and Extranet and can be called as private networks.
• Internet can be access through without having user account. While user account is the first important condition in case of Intranet and Extranet.

Internet has no hard and fast policies while there is a complete organization policy behind the setup of Intranet and Extranet.

What is post method?

By design, the POST request method requests that a web server accept the data enclosed in the body of the request message, most likely for storing it. It is often used when uploading a file or when submitting a completed web form. In contrast, the HTTP GET request method retrieves information from the server.

• GET - Requests data from a specified resource
• POST - Submits data to be processed to a specified resource

GET is usually intended to retrieve some data, and is expected to be idempotent (repeating the query does not have any side-effects) and can only send limited amounts of parameter data to the server.

What is an HTTP connection?

HTTP persistent connection, also called HTTP keep-alive, or HTTP connection reuse, is the idea of using a single TCP connection to send and receive multiple HTTP requests/responses, as opposed to opening a new connection for every single request/response pair.

Connection: keep-alive

HTTP - Requests

An HTTP client sends an HTTP request to a server in the form of a request message which includes following format:

A Request-line
Zero or more header (General|Request|Entity) fields followed by CRLF
An empty line (i.e., a line with nothing preceding the CRLF) 
indicating the end of the header fields
Optionally a message-body

HTTP - Responses

After receiving and interpreting a request message, a server responds with an HTTP response message:

A Status-line
Zero or more header (General|Response|Entity) fields followed by CRLF
An empty line (i.e., a line with nothing preceding the CRLF) 
indicating the end of the header fields
Optionally a message-body

HTML

Hypertext Markup Language, a standardized system for tagging text files to achieve font, colour, graphic, and hyperlink effects on World Wide Web pages.

SGML

The standard generalized markup language (SGML) arose in the 1980s as a method to markup electronic documents through various tags. This makes SGML one of the first meta-languages for document creation and presentation. The International Organization for Standardization (ISO) made SGML the international standard for describing markup in electronic documents in 1986 through ISO 8879.

Tim Berners-Lee created the World Wide Web in 1989 and also developed a standardized markup language to create and display text-based content that could be served across the Internet. Berners-Lee took the tagging methodology used in SGML and built the hypertext markup language (HTML) and a web browser that interpreted HTML tags in 1990.

The earliest iteration of HTML used 18 tags -- many of which are still in use with the latest versions of HTML; the most recent version of HTML (HTML5) was released in October 2014.

XML

The extensible markup language (XML) was developed and released in 1998 by the World Wide Web Consortium as a standard means of to add markup to documents. Users can create the tags they need and define how those tags are used. XML has grown in popularity for its capabilities to store and transfer data between applications. XML documents essentially play a role as data files for other applications. For example, an application's configuration file is often saved as an XML file rather than a simple text file.

Comparison between SGML and HTML:

	SGML	HTML
Full Form	It stands for the Standard Generalized Markup Language.	It stands for Hyper Text Markup Language.
Type	application/sgml, text/sgml	text/html
Type code	Text	Text
Uniform type	public.xml	public.html
Developed by	ISO	WWW Consotium
Format type	It is a mark up language.	It is a mark up language.
Extended from	GML	SGML
Extended to	HTML,XML	XHTML

WWW

The World Wide Web (abbreviated WWW or the Web) is an information space where documents and other web resources are identified by Uniform Resource Locators (URLs), interlinked by hypertext links, and can be accessed via the Internet.

HTTP

The Hypertext Transfer Protocol (HTTP) is an application protocol for distributed, collaborative, and hypermedia information systems.^[1] HTTP is the foundation of data communication for the World Wide Web.

Hypertext is structured text that uses logical links (hyperlinks) between nodes containing text. HTTP is the protocol to exchange or transfer hypertext.

web server

A web server is a computer system that processes requests via HTTP, the basic network protocol used to distribute information on the World Wide Web. The term can refer to the entire system, or specifically to the software that accepts and supervises the HTTP requests.

web client or web browser

A web browser (commonly referred to as a browser) is a software application for retrieving, presenting and traversing information resources on the World Wide Web. An information resource is identified by a Uniform Resource Identifier (URI/URL) that may be a web page, image, video or other piece of content.^[1] Hyperlinks present in resources enable users easily to navigate their browsers to related resources.

javascript

JavaScript (/ˈdʒɑːvəˌskrɪpt/^[6]), often abbreviated as JS, is a high-level, dynamic, weakly typed, object-based, multi-paradigm, and interpreted programming language. Alongside HTML and CSS, JavaScript is one of the three core technologies of World Wide Webcontent production. It is used to make webpages interactive and provide online programs, including video games. The majority of websites employ it, and all modern web browsers support it without the need for plug-ins by means of a built-in JavaScript engine.

2.Difference between UDP and TCP?

	TCP	UDP
Acronym for	Transmission Control Protocol	User Datagram Protocol or Universal Datagram Protocol
Connection	TCP is a connection-oriented protocol.	UDP is a connectionless protocol.
Function	As a message makes its way across the internet from one computer to another. This is connection based.	UDP is also a protocol used in message transport or transfer. This is not connection based which means that one program can send a load of packets to another and that would be the end of the relationship.
Usage	TCP is suited for applications that require high reliability, and transmission time is relatively less critical.	UDP is suitable for applications that need fast, efficient transmission, such as games. UDP's stateless nature is also useful for servers that answer small queries from huge numbers of clients.
Use by other protocols	HTTP, HTTPs, FTP, SMTP, Telnet	DNS, DHCP, TFTP, SNMP, RIP, VOIP.
Ordering of data packets	TCP rearranges data packets in the order specified.	UDP has no inherent order as all packets are independent of each other. If ordering is required, it has to be managed by the application layer.
Speed of transfer	The speed for TCP is slower than UDP.	UDP is faster because error recovery is not attempted. It is a "best effort" protocol.
Reliability	There is absolute guarantee that the data transferred remains intact and arrives in the same order in which it was sent.	There is no guarantee that the messages or packets sent would reach at all.
Header Size	TCP header size is 20 bytes	UDP Header size is 8 bytes.
Common Header Fields	Source port, Destination port, Check Sum	Source port, Destination port, Check Sum
Streaming of data	Data is read as a byte stream, no distinguishing indications are transmitted to signal message (segment) boundaries.	Packets are sent individually and are checked for integrity only if they arrive. Packets have definite boundaries which are honored upon receipt, meaning a read operation at the receiver socket will yield an entire message as it was originally sent.
Weight	TCP is heavy-weight. TCP requires three packets to set up a socket connection, before any user data can be sent. TCP handles reliability and congestion control.	UDP is lightweight. There is no ordering of messages, no tracking connections, etc. It is a small transport layer designed on top of IP.
Data Flow Control	TCP does Flow Control. TCP requires three packets to set up a socket connection, before any user data can be sent. TCP handles reliability and congestion control.	UDP does not have an option for flow control
Error Checking	TCP does error checking and error recovery. Erroneous packets are retransmitted from the source to the destination.	UDP does error checking but simply discards erroneous packets. Error recovery is not attempted.
Fields	1. Sequence Number, 2. AcK number, 3. Data offset, 4. Reserved, 5. Control bit, 6. Window, 7. Urgent Pointer 8. Options, 9. Padding, 10. Check Sum, 11. Source port, 12. Destination port	1. Length, 2. Source port, 3. Destination port, 4. Check Sum
Acknowledgement	Acknowledgement segments	No Acknowledgment
Handshake	SYN, SYN-ACK, ACK	No handshake (connectionless protocol)