1. Extensions are called top-level domains.

2. File extensions are used so that the computer's operating system or OS can recognize the file type.

3. A file extension primarily refers to a suffix added to the end of a computer file (an object containing information, data or commands) to define the file type.

1. Personal email account Microsoft Exchange is usually used to download e-mail to your computer.

2. Microsoft Exchange Server is Microsoft's email, calendaring, contacts, scheduling, and collaboration platform.

3. It is deployed on the Windows Server operating system (OS) for business use.

4. Microsoft designed Exchange Server to provide users with access to the messaging platform from mobile devices, desktops, and web-based systems.

1. Optical fibres use total internal reflection to transfer data. The primary condition for total internal reflection is that the signal must travel from an optically denser medium to an optically rarer medium. Secondly, the angle of incidence must be greater than the critical angle.

The following devices are used to transmit network data.

- Microwave (Microweb)

- Infrared

- Radio Channel

1. To send an email, the sender's email address is mandatory. An email address is a unique identifier that connects an email message to a specific user.

2. Other required information for sending the email includes-

- Recipient's Email Address

- The subject of the email