The document discusses various topics related to data communication and computer networks including: - The definition of data communication as the sharing of virtual messages and computer networks as linking computers to share resources. - The differences between data communication, which can be local or remote, and computer networks, which enable file sharing and information transfer. - Key terms related to networking including nodes, LANs, PANs, MANs, WANs, NICs, MAC addresses, IP addresses, ports, and the differences between hubs, switches, routers, bridges, and repeaters. - Explanations of bits, bytes, bridges, and the differences between MAC addresses and IP addresses.

1. Spring 2021
Assignment —1
Md Zakir Hossain
Id: 1925102518
Course Title: Data Communication
_____________________________
What is data communication?
Ans. Data communication refers to the sharing of a virtual message.
What is network?
Ans. A network consists of two or more computers that are linked in order to share resources (such as
printers and CDs), exchange files, or allow electronic communications. The computers on a network may
be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.
What is the difference between data communication and computer networks?
Ans.
Computer Network:
A computer network is a group of computer systems and other computing hardware devices that are
linked through the communication channels. A Computer Network enables file sharing across the
network. It helps the web information to traverse more easily and conveniently. It allows the sharing of
software and operating systems on remote systems. Based on the area of networking, Computer Networks
are of several types.
Data Communication:
When we communicate, we are sharing information. This sharing can be local or remote. Between
individuals, local communication usually occurs face to face, while remote communication takes place
over distance.
Both analog and digital data can be transferred through mainly these two processes.
What is Node?
Ans. Any system or device connected to a network is also called a node. For example, if a network
connects a file server, five computers, and two printers, there are eight nodes on the network. Each device
on the network has a network address, such as a MAC address, which uniquely identifies each device.
What is LAN?

2. Ans. A local area network (LAN) is a collection of devices connected together in one physical
location, such as a building, office, or home. ... Regardless of size, a LAN's single defining
characteristic is that it connects devices that are in a single, limited area.
What is PAN?
Ans. Personal area networks (PAN) are short-range wireless networks that work over a range of
tens of meter.
What is MAN?
Ans. Stands for "Metropolitan Area Network." A MAN is a network that spans a large area, such
as a town or city.
What is WAN?
Ans. In its simplest form, a wide-area network (WAN) is a collection of local-area networks
(LANs) or other networks that communicate with one another. A WAN is essentially a network
of networks, with the Internet the world's largest WAN.
What is NIC?
Ans. A network interface card (NIC) is a hardware component without which a computer cannot
be connected over a network. It is a circuit board installed in a computer that provides a
dedicated network connection to the computer. It is also called network interface controller,
network adapter or LAN adapter.
What is Mac Address?
Ans. A media access control address (MAC address) is a unique identifier assigned to a network
interface controller (NIC) for use as a network address in communications within a network
segment. This use is common in most IEEE 802 networking technologies, including Ethernet,
Wi-Fi, and Bluetooth.
What is IP Address?
Ans. An IP address is a string of numbers separated by periods. IP addresses are expressed as a
set of four numbers — an example address might be 192.158. 1.38. Each number in the set can
range from 0 to 255.
What is Port?
Ans. A port is a virtual point where network connections start and end. Ports are software-based
and managed by a computer's operating system. Each port is associated with a specific process or
service.
What is difference between Hub, Switch, Router, Bridge, Repeaters?

3. Ans.
Hub – A hub is basically a multiport repeater. A hub connects multiple wires coming from
different branches, for example, the connector in star topology which connects different stations.
Hubs cannot filter data, so data packets are sent to all connected devices. In other words,
collision domain of all hosts connected through Hub remains one. Also, they do not have the
intelligence to find out best path for data packets which leads to inefficiencies and wastage.
Repeater – A repeater operates at the physical layer. Its job is to regenerate the signal over the
same network before the signal becomes too weak or corrupted so as to extend the length to
which the signal can be transmitted over the same network. An important point to be noted about
repeaters is that they do not amplify the signal. When the signal becomes weak, they copy the
signal bit by bit and regenerate it at the original strength. It is a 2 port device.
Bridge – A bridge operates at data link layer. A bridge is a repeater, with add on the
functionality of filtering content by reading the MAC addresses of source and destination. It is
also used for interconnecting two LANs working on the same protocol. It has a single input and
single output port, thus making it a 2 port device.
Switch – A switch is a multiport bridge with a buffer and a design that can boost its efficiency(a
large number of ports imply less traffic) and performance. A switch is a data link layer device.
The switch can perform error checking before forwarding data, that makes it very efficient as it
does not forward packets that have errors and forward good packets selectively to correct port
only. In other words, switch divides collision domain of hosts, but broadcast domain remains
same.
Routers – A router is a device like a switch that routes data packets based on their IP addresses.
Router is mainly a Network Layer device. Routers normally connect LANs and WANs together
and have a dynamically updating routing table based on which they make decisions on routing
the data packets. Router divide broadcast domains of hosts connected through it.
What is bit and byte?
Ans.
Bit— A bit is a binary digit, the smallest increment of data on a computer. A bit can hold only
one of two values: 0 or 1, corresponding to the electrical values of off or on, respectively.
Byte— the basic unit of information in computer storage and processing. A byte consists of 8
adjacent binary digits (bits), each of which consists of a 0 or 1.
What is Bridge?
Ans. A network bridge is a computer networking device that creates a single, aggregate network
from multiple communication networks or network segments.

4. What is difference between IP address & Mac address?
Ans.
Mac address:
1. MAC Address stands for Media Access Control Address.
2. MAC Address ensure that physical address of the computer is unique.
3. MAC Address is of six byte hexadecimal address.
4. MAC Address can be retrieved using ARP protocol.
IP address
1. IP Address stands for Internet Protocol Address.
2. IP Address is a logical address of the computer and is used to uniquely locate computer
connected via a network.
3. IP Address is of 4 bytes or of 16 bytes.
4. IP Address can be retrieved using RARP protocol.
Source:
# Google
# ICT book of class xi