O LEVEL- INTERNET TECHNOLOGY & WEB DESIGN

O LEVEL-PAPER 2nd -- M2-R4 :

INTERNET TECHNOLOGY & WEB DESIGN

THESE ARE THE QUESTIONS WHICH FREQUENTLY ASKED IN 

  LAST 10 YEARS -----

Definition of SMTP

SMTP (Simple Mail Transfer Protocol) is a Message Transfer Agent (MTA). There are two MTAs client MTA and server MTA. A client MTA at clients system sends mail which is received by the server MTA at client’s mail server. Further, the client mail server has client MTA which sends the mail from client’s mail server to the server MTA at recipient’s mail server.  SMTP is a protocol that defines both client-server MTA, on the internet.

SMTP protocol is used in the scenario where both the sender and receiver of mail must be connected to their mail server by WAN or LAN. SMTP protocol is used two times, first between sender and its mail server and second between client’s mail server and receivers mail server. SMTP is not used between receiver’s mail server and receiver; the POP protocol accomplishes this task.

concentrate on the working of SMTP. SMTP defines the command and responses that are used to transfer the messages between client and server MTA. The commands are sent from client to the server. The responses are sent back from the server to the client.

The mail transfer between Client MTA and Server MTA occurs in three phases: Connection establishment, mail transfer, and Connection termination. Initially, the connection is established between client and server MTA. After the connection is established, a single mail is exchanged between the single sender and several recipients. After the succesful transfer of the message the connection is terminated by the client.

Definition of POP3

As we have seen above SMTP accomplishes the mail delivery task from client to server MTA. Now a  pull protocol is required to pull the mail from the MTA server to the receiver. For this, we have POP3 protocol i.e. Post Office Protocol version 3. It is message access agent.

The POP3 has client and server MAA; client MAA software is installed on the recipient computer whereas, the server MAA is installed on the recipient’s mail server. To access/read the mail the user has to first download the mail from mailbox on mail server to its computer.

To access mail from the mail box present at the mail server the client MAA at recipient computer establishes the connection with the mail server using TCPport 110. For establishing connection client MAA at recipient’s computer sends username and password to the mailbox. Then the user is authenticated to retrieve mail messages one by one.

POP3 works on two modes delete mode and keep mode. Delete mode, deletes the mail from the mailbox after its retrieval and this mode is used when the user is working at his permanent computer. As the mails can be saved and organized on the user’s permanent computer, it need not be remaining in the mailbox.

Keep mode is used when the user is not working on its permanent computer. In keep, mode mails remain in the mailbox even after its retrieval for later organizing of mails on the user’s permanent computer.

IRC

Internet Relay Chat (IRC) is an open protocol that allows users with an IRC client to exchange text messages in real time over the Internet. Created by Jarkko Oikarinen in 1988, IRC was one of the first chat systems to allow more than two participants to join in a discussion.

Like email, IRC was another application that added to the popularity of the Internet before the existence of the World Wide Web. Using an IRC client, users could connect to IRC servers and message in real time with people all over the world and join larger groups (channels). Although this is now commonplace, IRC was an early indication of the Internet’s power to create communities where time and distance would have once made it impossible. Like many aspects of the Internet, the request for comments (RFC) system was central to creating and improving IRC

SSI

The Simple Sensor Interface (SSI) protocol is a simple communications protocol designed for data transfer between computers or user terminals and smart sensors. The SSI protocol is an Application layer protocol as in the OSI model.

The SSI protocol has been developed jointly by Nokia, Vaisala, Sunnto, Ionific, Mermit and University of Oulu. Currently SSI is being developed within the Mimosa Project, part of the European Union Framework Programmes for Research and Technological Development.

The SSI protocol is used in point-to-point communications over UART and networking nanoIP applications. SSI also provides polling sensors and streaming sensor data. For RFID sensor tags SSI specifies memory map for sensor data.

The criteria for SSI protocol development are:

·         general purpose

·         simple – minimal overhead

·         small footprint on the server (sensor) side

WIRELESS NETWORK

A wireless network is a computer network that uses wireless data connections between network nodes.

Wireless networking is a method by which homes, telecommunications networks and business installations avoid the costly process of introducing cables into a building, or as a connection between various equipment locations. 

Wireless telecommunications networks are generally implemented and administered using radio communication. This implementation takes place at the physical level (layer) of the OSI model network structure.

Examples of wireless networks include cell phone networks, wireless local area networks (WLANs), wireless sensor networks, satellite communication networks, and terrestrial microwave networks.

There are four main types of wireless networks: 

• Wireless Local Area Network (LAN): Links two or more devices using a wireless distribution method, providing a connection through access points to the wider Internet.
• Wireless Metropolitan Area Networks (MAN): Connects several wireless LANs.
• Wireless Wide Area Network (WAN): Covers large areas such as neighboring towns and cities.
• Wireless Personal Area Network (PAN): Interconnects devices in a short span, generally within a person’s reach