NETWORK IMPORTANT QUESTIONS

1) What are the components that are used in computer network.
Ans.: * Server
* Workstations
* Network Interface cards
* Cabling system
* Shared resources and peripherals.

2) What is the use of network interface cards.
Ans.: Network Interface Cards are used to control the flow of data between Personal computers and Workstations.
Network Interface Cards lie at Data Link Layer.

3)  What is the standard supported by Wireless LANS?
Ans.: 802.11

4) Which is the backbone of networking.
Ans.:Routers (Also called as Gateways.)

5) What is a Brouter.
Ans.:It is a combination of Bridge and Router.
Shortcut:  Brouter=Bridge+Router

6) Concurrency control is managed by
Ans.:Session Layer

7) . What is a Half Duplex.
Ans.:Data that can flow in both direction but in only one direction at a time.

8) What is Isosynchronous transmission.
Ans.:It is a cluster of Synchronous and Asynchronous transmission.
Tip: Isosynchronous =Synchronous+Asynchronous

9) Describe the use of ISDN.
Ans.:ISDN stands for Integrated Services Digital Network.
ISDN is used to integrate WAN with voice tile services.

10) What is congestion.
Ans.:Congestion is a situation that occurs when too many packets are to be sent over the network resulting in decrease in performance speed.

11)  Who is a cracker.
Ans.:A cracker is one who breaks into  a computer system without authorization aimed to destroy, steal secret,personal,confidential information.

12) What is spoofing.
Ans.:It is a technique of creating fake responses to keep a session active and prevent timeouts.

13) A standard e-mail supports 
Ans.:RFC 822 Standard(Message Format).

14) Bandwidth of fibre optic cables
Ans.:1 Gbps

15) What is the Use of a concentrator.
Ans.:Used to connect more devices to a computer.

16) What are the types of transmission technology and transmission media?
Ans.: Transmission technolgies- Broadcast  and Point to Point
Transmission media- Guided(Wired) and Unguided(Unwired) media.

17) What are the ways in which data can be exchanged?
Ans.: Simplex-Data can flow in one direction only.
Half-Duplex- Data can flow in both direction but in one direction at a time.
Full Duplex- Data can flow in both diretion at the same time.

18) What is the difference between baseband signal and broadband signal?
Ans.: Baseband signal-The entire bandwidth of the cable is consumed by a single signal.
Broadband signal-The bandwidth is utilised by multiple frequencies, allowing multiple signals to be sent at the simaltaeously.

19) Toplogies of network.
Ans.: Bus Topology: Each computer is directly connected to a network cable on a single line.
Star topology: All computers connected to a central hub.
Ring topology: All computers are connected in a loop.

20)What is mesh network
Ans.: A network in which there are multiple network links between computers to provide multiple ways for data to travel is called as a mesh network. 

SOFTWARE ENGINEERING AND SOFTWARE TESTING MCQS

1) What is formal information system.
Ans.: The flow of information from top level to bottom level.
Example: Memos, Instructions.

2) What are the different types of software system development life cycles.
Ans.: 1. Waterfall model or waterfall model
2. Prototype model
3. Object-oriented model
4. Dynamic systems development model

3) Which type of system development life cycle is based on iterative structure of system development.
Ans.: Prototype model

4) Which model is also called as Barry Boehm model.
Ans: Spiral model, which incorporates both top-down and bottom-up approaches.
It also has risk management criteria.
Tip: Cocomo model was also developed by Barry Boehm.

5) Expansion of Cocomo is
Ans.: Constructive Cost Model

6) What is the use of a Data Flow Diagram in Software engineering.
Ans.: Data flow diagram is used to describe the logical operation of a system.
Hint: It describes what a system does

7) What are the two types of Data Flow Diagrams.
Ans.: 1. Physical DFDs- Used during analysis phase
2. Logical DFDs- Used during design phase for depicting data flow.

8) What is a traceability matrix.
Ans.: It is a table that correlates requirements and design phase documents to test documents.

9) What is white box testing in software engineering.
Ans.: Testing the internal components of a software product.
Example: Loops, Execution paths.

10) Equivalence class partitioning and Boundary value Analysis are examples of.
Ans.: Black Box Testing

11) What are the different types of software testing.
Ans.: 1. Unit Test
2. Integration Test
3. System Test
4. Acceptance Test

12) What is Capability Maturity Model (CMM).
Ans.: Capability Maturity Model is based on the principles of Total Quality Management(TQM) to improve software development process.

13) What are the different stages in CMM.
Ans.: 1. Initial
2. Repeatable
3. Defined
4. Managed
5. Optimized.

14) What is Formal Technical Review (FTR)
Ans.: It is a software quality assurance activity aimed to uncover errors in function, logic, implementation.

15) What is clean approach.
Ans.: It is a software development technique used to produce software with a certifiable level of reliability.

MODEL SOLVED MCQS

1) Problems in computer security is mostly caused by
Ans.: Ever increasing DOS attacks.

2) TTL token pole circuit is used for
Ans.: Voltage regulation

3) What are Network support layers
Ans.: Physical layer
Data link layer
Network layer
Transport layer

4) What are User support layers.
Ans.: Session layer
Presentation layer
Session layer

5)  Logical Link Control(LLC) standard is
Ans.: 1EEE 802.2

6) Type 0 grammar also called as
Ans.: Unrestricted grammar

7)  Verification and validation are components of
Ans.: Software Quality Assurance.

8) Application of function point analysis
Ans.: It is used to estimate and measure size of software.

9) Activity diagrams are used to 
Ans.: Express relation between systems and sub-system.

10) GSM (Global System for Mobile Communication) supports 
Ans.: TDMA (Time Division Multiplex Access).

11) Extract and Load data process in data warehousing is done by
Ans.: Load Manager

12)Line code is used to.
Ans.: Convert digital data into digital signal 

13)Expand FURPS
Ans.: F-Functionality
U-Usability
R-Reliability
P-Performance
S-Support ability 

14) Asynchronous Transfer MODE (ATM) has how many bytes.
Ans.: 53 bytes
Note: Header of ATM is 5 bytes.
Also called as cell relay.

15)  Serial to parallel processing is done by
Ans.: De-multiplexer.

MODEL SOLVED MCQS

1) Top down parsers are called as predictive parsers because
The next lower level of the parse tree is predicted.

2) Which level is called as "Managed" in capability maturity model
Level 2
Note: 
Level 1: Initial
Level 2: Managed
Level 3: Defined
Level 4: Quantitatively managed
Level 5: Optimizing 

3) What is an external error.
An error whose cause cannot be identified anywhere within the software system.

4) The term "Black" in Black box testing denotes that
The design is hidden.

5) CASE tool and RAD tools are used during 
System analysis stage of System Development Life cycle.

6) Shortest propagation delay is generated by 
Ans.: ECL (Emitter Control Logic)

7) In Unix, kernel is used during while
Ans.:*Reading a file
*Pressed key
*Resource allocation

8) Find out the post fix of the given pre fix expression
*+pq-rs
Ans.: pq+rs-*

9) The topology used in Campus Area Network(CAN) is
Ans.: FDDI ring

10) Wi-Fi standard is
Ans.: 802.11a

11) A Destructor takes how many arguments.
Ans.:  Zero arguments.

12) Use of Digital Differential Analyzer(DDA) Algorithm in computer graphics.
Ans.: DDA is a Line drawing and scan conversion algorithm

13) What is a tree.
Ans.: A graph 'G' with n-1 edges is a tree.
A tree is generally connected, cycle free.

14) 2-D arrays are also called as
Ans.: Matrix/Table arrays.

15) What is the use of sniffer.
Ans.: Sniffer monitors data travel on a network.

16) The objects that are shared by application in Windows.
Ans.: COM (Component Object Model)

17) What is the difference between Random scan and Raster scan.
Ans.: Random scan draws a picture one line at a time.
Raster scan draws a picture on screen at a time.(Draws whole picture at a time)

18) Essential hazards generally occur in.
Ans.:  Toggle circuit and Asynchronous circuit

19) Work of Session layer.
Ans.: Name Recognition, dialog control, synchronization, security.

20)  Congestion controller in networking is 
Ans.: Network Layer

DISCRETE STRUCTURES SOLVED MCQS

1) The technique of automation with a stack as an auxiliary storage is called as

Pushdown Automata

2) Context Free Grammar(CFG) is

A language generator

3) A graph is a collection of 

Vertices and edges

4) A graph with no edges is called as

Empty graph or Trivial graph

5) A graph 'G', which is a connected acyclic graph is called asTree

Note: A tree has no cycles

6) A tree having a main node, which has no predecessor is called as

Rooted tree

7) All the vertices of a walk except the first and last vertices is called as

Internal vertices

8) In a tree, between every pair of vertices there is 

Exactly one path

9) Transitive and Irreflexive property imply

Asymmetric 

Shortcut:  

T and I = A

10) A graph 'g' is said to be Eulerian Graph if 

All vertices of graph 'g' is of even degree.

Tip: Eulerian graph=even degree

11) Context free languages are closed under

Union,keene closure

12) A bag contains 10 white balls and 15 black balls. Two balls are drawn in succession. Find out the probability that one is black and other is white.

1/2

Explantation:Total probability =(10+15)=25

So we have to take two balls from 25 balls, i.e., 25C2=300

Probability of choosing one white ball =10C1=10

probability of choosing one black ball=15C1=15

Therefore, Probability of getting one black ball and one white ball is

(10*15)/300=1/2

13) The collection of all subsets of a set is called as

Power set

14) A language is said to be regular only if it is accepted by a 

Finite automata

15) The intersection of a CFL and regular language is always

Regular and Context free.

16) The major difference between Moore machine and Mealy machine is

In Moore machine, the output depends only on the PRESENT state.

17) The recoginising capability of Non deterministic finite automata (NDFA) and deterministic finite automata (DFA)should be 

Same.

18) One of the limitation of Finite state automata (FSM) is that

It cannot remember arbitrary large amount of data.

19) A Finite state automata can be called as Turing machine (TM) because of.

Finite tape length, without rewinding capability, unidirectional tape movement.

20) A Turing Machine (TM) is more powerful than Finite State Automata (FSM) because

It has the capability to remember arbitrary long sequences of input symbols.

CURRENT COMPUTER TRENDS AND TECHNOLOGY

1) What are virtual data warehouse.
Virtual data warehouses provide views of operational databases that are materialised for efficient access.

2) Declaration of API routines should be located in
Module-level code

3) Each Activex control is accompanied by
Digital signature-A hash of code signed by creator of the control using public key cryptography

4) Difference between java and Activex is 
Portability,security

5) Activex controls are verified in Microsoft using
Authentic code.

6) Data minig tools generally make use of 
ODBC interface

7) Data mining addresses 
Inductive knowledge

8) Data warehouses are extensions of
Database views

9) GIS applications are conducted using
Interpolation

10) GIS data can be represented in
Vector and Raster formats.

CURRENT COMPUTER TRENDS AND TECHNOLOGY

1) The mechanism that allows several users to share a medium without interference is called as
Multiplexing.

2) The cost of parallel processing is generally determined by
Time complexity

3) A data warehouse is generally
Subject oriented

4) The process speeds of pipeline segments are
Equal

5) Key features of ATM (Asynchronous Transfer Mode)
ATM provides both real time and non real time service.
ATM provides faster packet switching than X.25
ATM was developed as part of work on broadband IDSN

6) What is ANSI-41
ANSI-41 is an interim standard that describes inter switching networking.

7) IEEE 802.11a is also called as
Wi-Fi 5

8) How many types of messages are used by MMS to perform message transactions.
Eight(8)

9) What is downflow.
Downflow is the process associated with archiving and backup of data.

10) The use of smart card is a type of
Authorization.

11) Wireless interconnections to PSTN is also called as
IXCs

12) E-commerce involves
EDI (Electronic Data Interchange)

13) U-NII(Unlicensed National Information Infrastructure) band operates at
5GHz frequency

14) What is the use of application software.
It is used to perform specific task for computer users.

15) PVM (Parallel Virtual Machine) has
One send buffer and one receive buffer.

16) Uses of data warehouse.
It provides storage,functionality,responsiveness to queries.

17) What are base stations.
They are just radio relays.

18) Traditional databases support 
OLTP (Online Transaction Processing)
Supports information query requirements.

19) Services provided by cloud computing
Infrastructure as a service (IaaS)
Platform as a service (PaaS)
Software as a service(SaaS)

20) What are data marts.
Data marts are tightly focused subsets of an organisation such as a department.

COMPUTER GRAPHICS SOLVED MCQS

1) What is CRT.
CRT stands for Cathode Ray Tube.
CRT is a large vacuum tube filled with some type of gas that is used to make images appear on the monitor screen.

2) What is a resolution.
Resolution is the number of pixels that is used to display a full screen image.

3) Expand the following:
1. LCD
2. LED
3. VGA
LCD-Liquid Crystal Display
LED-Light Emitting Diode

VGA-Video Graphics Array

4) Gas plasma flat panel displays make use of which gas.
Neon gas

5) What is a dot pitch.
Dot pitch is the measurement of space that exists between display pixels of the monitor.

6) What is refresh rate.
Refresh rate is the number of times an image is redrawn each second.

7) What is meant by bit depth.
The number of bits used to describe a pixel is called as bit depth.

8) What are the colors used in printing a document.
Cyan ink- It absorbs red color.
Magenta- It absorbs green color.
Yellow ink- It absorbs blue color.
Black ink- It absorbs red,blue,green colors equally.
Tip: CMYB combination.

9) Applications of computer graphics.
Entertainment
User interfaces
Medicine
Multimedia systems
Computer games
Image processing
Cartography

10) What are the basic 2-D transformations.
Translation
Scaling
Rotation
Tip: TSR

11) Expand the following terms:
MHEG
PREMO
SGML
ODA
WORM
MHEG- Multimedia/Hypermedia Expert Group
PREMO- Presentation Environment for Multimedia Objects
SGML- Standard Generalized Markup Language
ODA- Open Document Architecture.
WORM- Write Once Read Many

12) What is sample space in probability.
Sample space means the total outcomes resulting out of an experiment.
Example: If we toss two coins, then the total sample space will be 
2^2=4
Because, A coin has two faces and there are two coins, so the answer is 4
Sample space of two coins: (HH,HT,TT,TH)

13) What is Huffman code
Huffman code is an entropy encoding algorithm technique used for lossless data compression.
Note: An example of lossless data compression is ZIP file.

14) Explain the use of syndrome decoding.
Syndrome decoding is done to decode a linear code over a noisy channel.
Noisy channel means a channel on which errors generally occur.

15) What is image registration.
It is the process of transforming different sets of data in to one coordinate system.

16) What are mutually exclusive events.
Mutually exclusive events means the occurence of one event prevents the happening of another event.
Example: If we toss a coin, either head or tail will come, but both will not come at a time.

FIRST PAPER SOLVED MODEL

1) Telephone is an example of
(A) linear communication
(B) non-linear communication
(C) circular
(D) mechanised
Ans.: (A) linear communication

2) Means of grapevine communication are
(A) formal
(B) informal
(C) critical
(D) corporate
Ans.: (B) informal

3) Classroom communication is normally considered as
(A) effective 
(B) affective
(C) cognitive 
(D) non-selective
Ans.: (C) cognitive

4) A person writes all the numbers from 0 to 99. The number of times digit 3 will be written is
(A) 18 
(B) 19
(C) 20 
(D) 21
Ans.: (C) 20 
Explanation: 03,13,23,30,31,32,33,34,35,36,37,38,39,43,53,63,73,83,93

5) The missing term in the series
2, 7, 24, 77, ?, 723 is
(A) 238 
(B) 432
(C) 542 
(D) 320
Ans.: (A) 238 
Explanation:
 2
(2*3)+1=7
(7*3)+3=24
(24*3)+5=77
(77*3)+7=238
(238*3)+9=723
Tip: Multiply each consecutive number by 3 and add by odd numbers.

6) In certain code HEALTH is written as KHDOWK. The code of NORTH will be
(A) QRUWK 
(B) RQWUK
(C) RWQUK 
(D) RWUKQ
Ans.: (A) QRUWK
Explanation: 
N+3=Q
O+3=R
R+3=U
T+3=W
H+3=K

7) Given below are some codes of arrangements of three items in order of wider scope. Select the correct code.
(A) Garments, cloth and shirts
(B) Cloth, garments and shirts
(C) Shirts, garments and cloth
(D) Garments, shirts and cloth
Ans.: (B) Cloth, garments and shirts

8) The Internet ethical protocol is called
(A) net protocol 
(B) netiquette
(C) net ethics 
(D) net morality
Ans.: (B) netiquette

9) Commercial messages on the net are identified as
(A) Net ads
(B) Internet commercials
(C) Webmercials
(D) Viral advertisements
Ans.: (C) Webmercials
Tip: Webmericals=Web+Commercials

10) GIF stands for
(A) Global Information Format
(B) Graphics Information Format
(C) Graphics Interchange File
(D) Graphics Interchange Format
Ans.: (D) Graphics Interchange Format 
Tip: JPEG stands for Joint Photographic Expert Group

11) Which one of the following is not an Operating System ?
(A) IBM AIX
(B) Linux
(C) Sun Solaris
(D) Firefox
Ans.: (D) Firefox
Tip: Firefox is a browser. 
Opera, chrome, safari internet explorer are also browsers.

12) In which of the following States the segment of population, which is in majority, enjoys the benefit of reservation of seats in the State Assembly ?
(A) Meghalaya and Mizoram
(B) Assam and Nagaland
(C) Madhya Pradesh and Assam
(D) Rajasthan and Arunachal Pradesh
Ans.: (A) Meghalaya and Mizoram
Tip: Both the states are part of 6th schedule of the constitution

13) Which of the following are the ways of acquiring Indian citizenship ?
1. Birth
2. Descent
3. Naturalisation
4. Incorporation of territory
Select the correct answer from the
code given below :
Codes :
(A) 1 and 2 
(B) 1 and 4
(C) 1, 2 and 3 
(D) 1, 2, 3 and 4
Ans.: (D) 1, 2, 3 and 4
Tip: Another way of acquiring citizenship is through registration.

14) A good teacher must be
(A) resourceful and autocratic
(B) resourceful and participative
(C) resourceful and authoritative
(D) resourceful and dominant
Ans.: (B) resourceful and participative

15) Which one of the following is the best method of teaching ?
(A) Lecture method
(B) Discussion method
(C) Demonstration method
(D) Question-Answer method
Ans.: (C) Demonstration method

16) Successful Communication in classroom teaching is
(A) Circular
(B) Reciprocal
(C) Directional
(D) Influential
Ans.: (B) Reciprocal 

17) Identify the correct sequence of research steps :
(A) Selection of topic, review of literature, data collection, interpretation of findings
(B) Review of literature, selection of topic, data collection, of findings
(C) Selection of topic, data collection, review of literature, interpretation of findings
(D) Selection of topic, review of literature, interpretation of findings, data collection
Ans.: (A) Selection of topic, review of literature, data collection, interpretation of findings

18) Which one of the following is a non probability sampling method ?
(A) Simple Random Sampling
(B) Stratified Sampling
(C) Cluster Sampling
(D) Quota Sampling
Ans.: (D) Quota Sampling

19) By the year 2022, the Climate Change Action Plan of Government of India aims at installing
(A) 20,000 MW of wind power
(B) 25,000 MW of wind power
(C) 20,000 MW of solar power
(D) 10,000 MW of solar power
Ans.: (C) 20,000 MW of solar power

20) Which of the following nations has the maximum per capita emissions of carbon di-oxide ?
(A) China
(B) Japan
(C) USA
(D) India
Ans.: (C) USA

NETWORK SECURITY AND CRYPTOGRAPHY BASICS

1) What is meant by network security.
Network security is the mechanism of protecting data flowing on a network from unauthorized access.
Some of the network security measures involves Data Encryption techniques and use of Passwords.

2) What is the difference between share level security and user level security.
Share level security: In share level security, access to a particular resource is based on password.
User level security: In user level security, access to a particular resource is based on username.
The security level of share level security is less than that of user level security because user level security is dependent on username.
                                          Share level security<User level security

3) What is a security policy.
Security policy is a written document which states the rules and regulations by which all users of the network must abide by.

4)What is the difference between a hacker and cracker.
Hacker:  A hacker is a person who writes programs in assembly language or system level languages.
Generally a hacker is supposed to be a honest person who works to break secret and security information of
unscrupulous persons. Example: Ethical Hacking
Cracker: A cracker is the one who breaks in to a computer system without authorization. His sole aim is to damage the systems of other people or group.
Example: Steal credit,debit card numbers,plant viruses, etc.
Note: Hacker-Good person
Cracker-Bad person. 

5) What is spoofing.
Spoofing is the technique of  creating fake responses to keep a session active and prevent timeouts.
It is also a network management technique to reduce traffic.

6) Expand NAT and its application.
NAT stands for Network Address Translation.
NAT hides the IP addresses of client stations in the network.

7) What is meant by cryptography.
Cryptography is the technique of converting plain text to cipher text and converting the cipher text to plain text.

8) What is public key cryptography.
Public key cryptography is also called as Asymmetric encryption.
It makes use of two keys-public key and private key
Public key is used to encrypt the message and Private key is used to decrypt the message.
Public key cryptography was invented by Whitefield diffie and martin hellman.

9) What is the difference between encryption and decryption.
Encryption means the conversion of original text(plain text) to cipher text(encrypted text)
Decryption means the conversion of cipher text(encrypted text) to original text(plain text).

10) What is the difference between symmetric encryption and asymmetric encryption. .
Symmetric encryption: It makes use of the same key both for encryption and decryption.
Asymmetric encryption: It makes use of two keys namely
Public key-Public key is used to convert the plain text to cipher text.(encryption)
Private key-Private key is used to convert cipher text to plain text.(decryption)

11) Which of the following is the size of Network bits and Host bits of Class A of IP address ?
 Network bits 14, Host bits 16

12) Which of the following field of the TCP header tells how many bytes may be sent starting at the byte acknowledged ?
Window size

13) If user A wants to send an encrypted message to user B. The plain text of A is encrypted with the 
Public Key of user B

14)  A _____ can forward or block packets based on the information in the network layer and transport layer header.
Proxy firewall

15) Expand UDP and its use.
UDP stands for User Datagram Protocol. 
UDP is a connectionless transport protocol.

DATABASE MANAGEMENT SYSTEM:SOLVED MODEL TEST PAPER

1) What is meant by functional dependency.
Functional dependency is the relationship between attributes such that the value of an attribute is determined by value of another attribute.
Example: Regno->Name (Functional Dependency)
That is, 'Name' is dependent on the attribute 'Regno'.
In this case, Regno is a primary key.

2) What is meant by transitive dependency.
Transitive dependency occurs when a non key attribute value is functionally dependent on another non key attribute.
Example: Empid->Jobtype
               Jobtype->Hourpay
In this case, Jobtype is dependent on Empid.
In the second case, Hourpay is dependent on Jobtype, which is a non key attribute.
Therefore, when a non key attribute is dependent on another non key attribute, it is called as transitive dependency.
Note: In Database Management System, dependencies are not required. So we go for NORMALIZATION    
to reduce dependencies.

3) The most desired level of normalization in DBMS  is
3NF  (3rd Normal Form)
Tip: For an effective DBMS, 3NF is most desirable and higher levels of 
normalization is not advisable.'
3NF means you got to reduce Transitive dependencies. 

4) What is the difference between primary key, composite keys.
Primary key: Primary key is used to uniquely identify each row of a table.
Tip: Primary key should be UNIQUE and NOT NULL.
Composite keys: If a table has more than one primary key in a table, then it is called as Composite keys.

5) What are anomalies. what are its types. How to solve them.
Anomalies are errors that generally occur due to bad database design.
There are three types of anomalies namely:
1. Insertion anomalies
2. Deletion anomalies
3. Update anomalies
We can solve anomalies by using normalization techniques.

6) What do you mean by a flat file database.
A flat file database is the one in which there are no programs.
It also does not possess cross file feature.
The main advantage of flat file database is that it provides management of User interfaces.

7) What are the types of data abstraction.
There are three types of data abstraction namely:
 Physical level abstraction
Logical level abstraction
 View level abstraction
Physical level abstraction: It is the lowest level of abstraction that describes How data are stored. 
Logical level abstraction: The middle level of abstraction that shows What data are stored and what is the relationship that exists among the data. 
View level: View level abstraction is the highest level of abstraction which shows only part of the entire database.
Shortcut trick: Physical level: How
                       Logical level: What
                       View level: Only part

8) What is data modeling.
Data modeling is the process of optimizing the way in which information is stored and used within an organization.
Data modeling provides a strong platform for development of systems design and system documentation.

9) What is denormalization in DBMS.
Denormalization is the reverse process of normalization.
Denormalization is the process of controlled introduction of redundancy(repetition) in the database.
The main aim of denormalization is to increase and improve query performance.

10) What is the difference between a tuple and an attribute.
A tuple denotes a row.
An attribute means a column.

DISCRETE STRUCTURES, NETWORKS, DIGITAL LOGIC FUNDAMENTALS BASICS

1) What is a set.
A set can be defined as an unordered collection of distinct objects.
Example: A={3,6,2,8,7} can be called as a "set"

2) What is the difference between a partial order relation and equivalence relation.
A relation that is Reflexive, Antisymmetric, Transitive is said to be a Partial order  relation.
A relation which is Reflexive, Symmetric and Transitive is called as an Equivalence relation.
 Shortcut: RAT=Partial order
                   RST=Equivalence

3) What is meant by negation.
Negation means the opposite of the given preposition.
Example:
The negation of the preposition 'A' is ~A.
The negation of True is False
The negation of False is True

4) What is the difference between Tautology,Contradiction,satisfactory.
Tautology: Tautology means all the resulting outputs are always True.
Contradiction: Contradiction happens when all the results are always False
Satisfactory: Satisfactory means outputs may be True or False

5) What is an Eulerian graph.
An Eulerian graph is one which should be connected and each of its vertices should be of even degree.

6) State the formulas for complete graph and connected graph.
Complete graph=n(n-1)/2
Connected graph=n-1

7) Mention the basic laws of boolean algebra.
1. Commutative law.
2. Associative law.
3. Distributive law.
Let A=1, B=2, C=3

1. Commutative law: 
A+B=B+A
Example: 1+2=2+1
A*B=B*A
Example: 1*2=2*1

2.  Associative law:
A+(B+C)=(A+B)+C
Example: 1+(2+3)=(1+2)+3
A*(B*C)=(A*B)*C
Example: 1*(2*3)=(1*2)*3

3. Distributive law:

A*(B+C)=(A*B)+(A*C)
Example: 1*(2+3)=(1*2)+(1*3)

8) Name the two de-morgan's theorems.
___    _ _
A+B=A.B
___   _  _ 
A.B=A+B

9) What is the difference between a latch and a flipflop
A latch has no clock signal and it is asynchronous.
A flipflop has a clock signal and it is synchronous (it has time frame).
Note: Latches and flipflops are basic building blocks of sequential circuits.

10) What is a register and what is the use of shift register.
A register consists of a set of flipflops used to store binary information.
A register which is able to shift the binary information either to the left or right is alled as shift register.

11) What is the application of Watson-Felix model in software engineering.
It is used to determine the effort, staff size and total cost based on LOC (Lines of Code) needed to develop a software.

12) State the port numbers used in HTTP, FTP, SMTP, POP3, TELNET.
HTTP: 80
FTP: 20 and 21
SMTP: 25
POP3: 110
TELNET: 23
Note: Both SMTP & POP3 are used in email technology but there is a difference between the two.
SMTP is used to send a mail.
POP3 is used to receive the mail.

13) Give two examples of WAN.
Asynchronous Transfer Mode(ATM)
Integrated Services Digital Network(ISDN)
Tip: WAN is based on packet switching technology.

14) How many layers are used in OSI and TCP/IP model.
7 layers in OSI and 4 layers in TCP/IP model.
OSI- Open System Interconnection (7 layers)
Physical layer - Defines physical characterstics of network(ex. electronic circuits)
Data link layer - Data encapsulation (ex. packets)
Network layer - Packet transmission
Transport layer - Delivery of packets from source to destination
Session layer - Manges network access
Presentation layer - Determines format of data (ex. data compress, decompress, encryption,etc.)
Application layer - Consists of the applications used by end user(ex. java, word, notepad,etc)

Shortcut: PDNTSPA 

TCP/IP MODEL (4 Layers)
Network layer - Mapping between IP addresses and network physical address
Internet layer - Makes datagrams and handles data routingm Makes use of IP.
Transport layer - Makes use of TCP and UDP,ensures data delivery services.
Application layer - HTTP,FTP, SMTP, etc are used here.

Shortcut: NITA

15. Explain the truth tables of basic gates.
                                                            AND GATE

A	B	A.B
0	0	0
0	1	0
1	0	0
1	1	1

  

OR GATE

A	B	A+B
0	0	0
0	1	1
1	0	1
1	1	1

NOT GATE

A	_ A
0	1
1	0

NAND GATE

A	B	___ A.B
0	0	1
0	1	1
1	0	1
1	1	0

NOR GATE

A	B	___ A+B
0	0	1
0	1	0
1	0	0
1	1	0