Class 12 | Computer Network Questions

Ans. The main features of 3G are
• Devices are called smartphones
• Fast communication, data speed between 144 kbps and 2mbps
• High quality voice transmission
• Supported multimedia
• Mobile TV, mobile internet
The salient features of 4G are
• Wireless broadband
• Based on LTE(Long Term Evolution)-Advanced is a series of upgrades to existing UMTS technology
• Significantly faster speed(100 Mbps-1Gbps)and reduced network congestion.
• High voice quality(as if voice is just next to you)

Ans. Steps involved in working of email are
• You compose and send email from your email client. Your email has a recipient’s email address along the email message.
• Now your email client connects to the Outgoing SMTP server and hands over the email message in the required format.
• The Outgoing SMTP first validates the sender details and if valid processes the message for sending and places it in outgoing queue.
• Next DNS look up takes place. The SMTP server based on the domain details in the recipient address, looks up the DNS server of the domain and retrieves the Recipient server information(MX records) of the recipient domain.( MX (mail exchange) records are DNS records that are necessary for delivering email to the recipient’s address.
• Then the SMTP server connects with the Recipient email server and sends the email through SMTP protocol.
• The recipient server in turn validates the recipient account and delivers the email to the users email account.
• The user logs into own email account and views the received email using email client that will use POP3/IMAP protocols.

Ans. To ensure the safety many internet security measures are employed. Some of them are :
• Encryption:- It is a technique that translates the original data into a form which is not a usable form of data. The encrypted data must be decoded or decrypted to bring it back to the original form. To decrypt the data a specific code called the decryption key is required
• HTTPS( Hypertext transfer protocol secure): It is a combination of HTTP and SSL/TSL protocols. HTTPS encrypts your data and establishes a secure channel over a non secure network to ensure protected data transfer. Thus the data is protected from the hackers and eavesdroppers who wants to intercept and access your data. SSL stands for Secure Socket Layer protocol. It encrypts the data so that a third party cannot eavesdrop on the transmission and view the data being transmitted. It requires that the website has SSL certificate installed which ensures its authenticity. Once installed, the sensitive information is obtained from the user through a secure connection over internet.

To work on the distant computers over the internet, there are two common network applications :
• Remote Desktop:- The remote desktop is a type of network application through which a person can work on the desktop of another computer ( which is at different location) in the same manner as if that computer is right in front of the person. The person connects to the remote computer( host computer) via own computer(client Computer) on which he/she is working. The remote desktop application displays the desktop of the host computer on the screen of the client computer , and the user can work on it as if it is his/her computer.
• Remote Login:- The remote login is a network application that permits a user sitting at a different location to work on a specific program on another computer. The work access to a program is granted by login concept wherein users having authorized login and password to work on that program are allowed access. TELNET and SSH are two programs that facilitate remote login on the internet. These programs help you to connect to the remote machine. Remote login is different from accessing information over the internet. It is an interactive data transfer where the user is interacting with remote program.