This document provides information about data communication and computer networks. It defines data communication as the exchange of data between a source and receiver via transmission media. A computer network is defined as an interconnection of computers that share resources through a communication medium. The key differences between data communication and computer networks are that computer networks can transfer data across large geographies, have different architectural layers, and connect multiple computers to share resources over long distances. The document also defines personal area networks (PANs), local area networks (LANs), metropolitan area networks (MANs), and wide area networks (WANs) based on their size and maximum transmission distances. It provides information about nodes, MAC addresses, network interface cards (NICs), IP addresses

1. Data Communication Notes
Presented By: Md. Faruk Hossain
Student ID: 1915002533
1. What is Data Communication?
Ans: Data communication refers to the exchange of data between a source and a
receiver via form of transmission media such as a wire cable. Data communication is
said to be local if communicating devices are in the same building or a similarly
restricted geographical area. The meanings of source and receiver are very simple. The
device that transmits the data is known as source and the device that receives the
transmitted data is known as receiver. Data communication aims at the transfer of data
and maintenance of the data during the process but not the actual generation of the
information at the source and receiver.
2. What is Computer Network?
Ans: A computer network is an interconnection of various computers to share software,
hardware, resources and data through a communication medium between them. The
connection between the separate computers can be done via a copper wire, fiber optics,
microwaves or communication satellite. A printer or computer, or any machine that is
capable of communicating on the network is referred to as a device or node. The
computers connected in a network share files, folders, applications and resources like
scanner, web-cams, printers etc.
3. What is the Difference between Data Communication and Computer Network?
Ans: Computer Network:
(a) Computer Network is best known to transfer the data and information
across different geographies.
(b)Computer network have different types of architectural layers for example
client-server, peer-to-peer or hybrid.
(c)In Computer Network, performance testing is more preferred than Data
Communication.
(d) The purpose of communication and resource sharing is achieved by multiple
computer linked through transmission media.
(e) A large community support provides by computer network and extensive
documentation libraries.

2. Data Communication:
(a) We can easily communicate and transfer the data across different nodes through
Data Communication.
(b) Data Communication usually have 3 architectural designs and can be useful in the
multi nodes transmission across different regions and areas.
(c) Data Communication doesn’t help in any data binding process and direct interrelated
testing for the communication parameter is a little bit difficult than networking.
(d) Through the network, we can transmit the data signal from one point to another.
(e) Data Communication also has one of the largest community supports.
4. What is a personal area network (PAN)?
Ans: A personal area network (PAN) connects electronic devices within a user's
immediate area. The size of a PAN ranges from a few centimeters to a few meters. One
of the most common real-world examples of a PAN is the connection between a
Bluetooth earpiece and a smartphone. PANs can also connect laptops, tablets, printers,
keyboards, and other computerized devices. It works maximum 10 m distance.
5. What is a LAN (local area network)?
Ans: A LAN, or local area network, is a group of connected computing devices within a
localized area that usually share a centralized Internet connection. Only 5000 devices of
network connected and upto 1 km area.
6. What is a metropolitan area network (MAN)?
Ans: A metropolitan area network (MAN) is smaller than a wide area network (WAN) but
larger than a local area network (LAN). it coverage upto 10 km distance.
7. What is a wide area network (WAN)?
Ans: A wide area network (WAN) is a large computer network that connects groups of
computers over large distances. WANs are often used by large businesses to connect
their office networks; each office typically has its own local area network, or LAN, and
these LANs connect via a WAN. it works world wide.
8. What is Node?
Ans: A node is any physical device within a network of other tools that’s able to send,
receive, or forward information. A personal computer is the most common node. It's
called the computer node or internet node.

3. 9. What is MAC address?
Ans: MAC address is a unique identifier that is assigned to a NIC (Network Interface
Controller/ Card). It consists of a 48 bit or 64-bit address, which is associated with the
network adapter. MAC address can be in hexadecimal format. The full form of MAC
address is Media Access Control address.
10. What is NIC?
Ans: Network Interface Card is a hardware device that is installed on the computer so
that it can be connected to the internet. It is also called Ethernet Card or Network
Adapter. Every NIC has a 48-bit unique serial number called a MAC address which is
stored in ROM carried on the card. Every computer must have at least one NIC if it
wants to connect to the internet.
11. What is IP address?
Ans: An Internet Protocol address (IP address) is a numerical label assigned to each
device connected to a computer network that uses the Internet Protocol for
communication.
12. Types of addressing?
Ans: There are two types of addressing, (i) Physical address: The MAC address is a
physical address also called a hardware address because it physically identifies an item
of hardware. (ii) Logical address: Logical address can either be a VLAN or a IP
Address.
13. What is port?
Ans: A computer port is a type of electronic, software- or programming-related docking
point through which information flows from a program on your computer or to your
computer from the Internet or another computer in a network.
14. What is Hub?
Ans: A hub is a network hub used for the connection of devices in a network. It connects
several devices in a LAN. All the network connection devices are connected through a
hub that acts as a central connection for all the devices. There are many ports in it, and
if a packet arrives only at one port, it is copied so that all the ports can see the packets.
This helps if there is any trouble in one port of the hub. The three types are active,
passive and intelligent. Active hubs amplify the incoming electric signal, whereas
passive hubs do not amplify the electric signal. Intelligent hubs are kind of active hubs.
Hub can not know ip address.

4. 15. What is Switch?
Ans: 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. Switch can detect MAC address.
16. What is Router?
Ans: 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. Router can detect MAC address and ip address.
17. What is Bridge?
Ans: 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.
18. What is Repeater?
Ans: 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.
19. What is the difference between Hub, Switch, Router, Bridge and Repeater?
Ans: Hub:
(i) A hub has a number of input lines that it joins electrically. Active hub and passive hub
are two types of hubs.
(ii) Frames arriving on any of the lines are sent out on all the others. It is broadcast
device. If two frames arrive at the same time, they will collide, just as on a coaxial cable.
(iii) All the lines coming into a hub must operate at the same speed. Hubs differ from
repeaters in that they do not boost the incoming signals and are designed for multiple
input lines, but the differences are slight.
(iv) Like repeaters, hubs are physical layer devices that do not examine the link layer
addresses or use them in any way. It is not an intelligent device.

5. Switch:
(i) Switches are modern bridges by another name. It acts as multiport bridge to connect
devices or segments in a LAN. It operates at data link layer.
(ii) It is point to point device.
(iii) It is an intelligent device. It uses switching table to find the correct destination.
Router:
(i) Routers are devices that connect two or more networks. It operates at network layer.
(ii) They consist of a combination of hardware and software.
(iii) The hardware can be a network server, a separate computer or a special device.
The hardware includes the physical interfaces to the various networks in the
internetwork.
(iv) These interfaces can be Token Ring, Ethernet, T1, Frame Relay, ATM or any other
technology.
Bridge:
(i) A bridge connects two or more LANs. It operates at data link layer.
(ii) Like a hub, a modern bridge has multiple ports, usually enough for 4 to 48 input lines
of a certain type. Unlike in a hub, each port is isolated to be its own collision domain.
(iii) When a frame arrives, the bridge extracts the destination address (for Ethernet, it is
48 bit) from the frame header and looks it up in a table to see where to send the frame.
(iv) The bridge only outputs the frame on the port where it is needed and can forward
multiple frames at the same time.
Repeater:
(i) The repeater operates in the physical layer.
(ii) These are analog devices that work with signals on the cables to which they are
connected.
(iii) A signal appearing on one cable is regenerated and put out on another cable.
Hence it extends the physical length of LAN.
(iv) Repeaters do not understand frames, packets or headers. They understand the
symbols that encode bit as volts.
(v) Classic Ethernet, for example, was designed to allow four repeaters that would boost
the signal to extend the maximum cable length from 500 meters to 2500 meters.