Data communication notes

Somes data communication related question and answer

1. Data Communication Notes
Presented By: Md. Faruk Hossain
Student ID: 1915002533
1. What is Data Communication?
Ans: Data communication refers to the exchange ofdata between a source and a
receiver via form of transmission media such as awire cable. Data communication is
said to be local if communicating devices are in thesame building or a similarly
restricted geographical area. The meanings of sourceand receiver are very simple. The
device that transmits the data is known as sourceand the device that receives the
transmitted data is known as receiver. Data communicationaims at the transfer of data
and maintenance of the data during the process butnot the actual generation of the
information at the source and receiver.
2. What is Computer Network?
Ans: A computer network is an interconnection of variouscomputers to share software,
hardware, resources and data through a communicationmedium between them. The
connection between the separate computers can be donevia a copper wire, fiber optics,
microwaves or communication satellite. A printer orcomputer, or any machine that is
capable of communicating on the network is referredto 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 Communicationand Computer Network?
Ans:Computer Network:
(a) Computer Network is best known to transfer thedata and information
across different geographies.
(b)Computer network have different types of architecturallayers for example
client-server, peer-to-peer or hybrid.
(c)In Computer Network, performance testing is morepreferred than Data
Communication.
(d) The purpose of communication and resource sharingis achieved by multiple
computer linked through transmission media.
(e) A large community support provides by computernetwork and extensive
documentation libraries.

2. Data Communication:
(a) We can easily communicate and transfer the dataacross different nodes through
Data Communication.
(b) Data Communication usually have 3 architecturaldesigns and can be useful in the
multi nodes transmission across different regionsand areas.
(c) Data Communication doesn’t help in any data bindingprocess and direct interrelated
testing for the communication parameter is a littlebit difficult than networking.
(d) Through the network, we can transmit the datasignal from one point to another.
(e) Data Communication also has one of the largestcommunity supports.
4. What is a personal area network (PAN)?
Ans:A personal area network (PAN) connects electronicdevices within a user's
immediate area. The size of a PAN ranges from a fewcentimeters to a few meters. One
of the most common real-world examples of a PAN isthe connection between a
Bluetooth earpiece and a smartphone. PANs can alsoconnect laptops, tablets, printers,
keyboards, and other computerized devices. It worksmaximum 10 m distance.
5. What is a LAN (local area network)?
Ans: A LAN, or local area network, is a group of connectedcomputing devices within a
localized area that usually share a centralized Internetconnection. 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 smallerthan a wide area network (WAN) but
larger than a local area network (LAN). it coverageupto 10 km distance.
7. What is a wide area network (WAN)?
Ans: A wide area network (WAN) is a large computernetwork that connects groups of
computers over large distances. WANs are often usedby large businesses to connect
their office networks; each office typically has itsown 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 networkof other tools that’s able to send,
receive, or forward information. A personal computeris 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 assignedto a NIC (Network Interface
Controller/ Card). It consists of a 48 bit or 64-bitaddress, which is associated with the
network adapter. MAC address can be in hexadecimalformat. The full form of MAC
address is Media Access Control address.
10. What is NIC?
Ans: Network Interface Card is a hardware device thatis installed on the computer so
that it can be connected to the internet. It is alsocalled Ethernet Card or Network
Adapter. Every NIC has a 48-bit unique serial numbercalled a MAC address which is
stored in ROM carried on the card. Every computermust 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) isa numerical label assigned to each
device connected to a computer network that uses theInternet Protocol for
communication.
12. Types of addressing?
Ans: There are two types of addressing, (i)Physicaladdress: The MAC address is a
physical address also called a hardware address becauseit physically identifies an item
of hardware. (ii)Logical address: Logical addresscan 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 programon your computer or to your
computer from the Internet or another computer ina network.
14. What is Hub?
Ans: A hub is a network hub used for the connectionof devices in a network. It connects
several devices in a LAN. All the network connectiondevices are connected through a
hub that acts as a central connection for all thedevices. There are many ports in it, and
if a packet arrives only at one port, it is copiedso that all the ports can see the packets.
This helps if there is any trouble in one port ofthe hub. The three types are active,
passive and intelligent. Active hubs amplify the incomingelectric signal, whereas
passive hubs do not amplify the electric signal. Intelligenthubs 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 bufferand 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 checkingbefore forwarding data, that
makes it very efficient as it does not forward packetsthat have errors and forward good
packets selectively to correct port only. In otherwords, switch divides collision domain
of hosts, but broadcast domain remains same. Switchcan detect MAC address.
16. What is Router?
Ans: A router is a device like a switch that routesdata packets based on their IP
addresses. Router is mainly a Network Layer device.Routers normally connect LANs
and WANs together and have a dynamically updatingrouting table based on which they
make decisions on routing the data packets. Routerdivide broadcast domains of hosts
connected through it. Router can detect MAC addressand ip address.
17. What is Bridge?
Ans: A bridge operates at data link layer. A bridgeis a repeater, with add on the
functionality of filtering content by reading theMAC addresses of source and
destination. It is also used for interconnecting twoLANs working on the same protocol.
It has a single input and single output port, thusmaking it a 2 port device.
18. What is Repeater?
Ans: A repeater operates at the physical layer. Itsjob is to regenerate the signal over
the same network before the signal becomes too weakor corrupted so as to extend the
length to which the signal can be transmitted overthe same network. An important point
to be noted about repeaters is that they do not amplifythe signal. When the signal
becomes weak, they copy the signal bit by bit andregenerate 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 joinselectrically. Active hub and passive hub
are two types of hubs.
(ii) Frames arriving on any of the lines are sentout on all the others. It is broadcast
device. If two frames arrive at the same time, theywill collide, just as on a coaxial cable.
(iii) All the lines coming into a hub must operateat the same speed. Hubs differ from
repeaters in that they do not boost the incoming signalsand are designed for multiple
input lines, but the differences are slight.
(iv) Like repeaters, hubs are physical layer devicesthat do not examine the link layer
addresses or use them in any way. It is not an intelligentdevice.

5. Switch:
(i) Switches are modern bridges by another name. Itacts as multiport bridge to connect
devices or segments in a LAN. It operates at datalink layer.
(ii) It is point to point device.
(iii) It is an intelligent device. It uses switchingtable 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 andsoftware.
(iii) The hardware can be a network server, a separatecomputer or a special device.
The hardware includes the physical interfaces to thevarious 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 operatesat 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 isolatedto be its own collision domain.
(iii) When a frame arrives, the bridge extracts thedestination address (for Ethernet, it is
48 bit) from the frame header and looks it up in atable to see where to send the frame.
(iv) The bridge only outputs the frame on the portwhere 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 signalson the cables to which they are
connected.
(iii) A signal appearing on one cable is regeneratedand put out on another cable.
Hence it extends the physical length of LAN.
(iv) Repeaters do not understand frames, packets orheaders. They understand the
symbols that encode bit as volts.
(v) Classic Ethernet, for example, was designed toallow four repeaters that would boost
the signal to extend the maximum cable length from500 meters to 2500 meters.