Engineering College (Under PSC)- Lecturer, 2017

                        Engineering College (Under PSC)- Lecturer, 2017

1.      How is cloud computing? How it works?

Cloud computing is the on-demand availability of computer system resources, especially data storage and computing power, without direct active management by the user. The term is generally used to describe data centers available to many users over the Internet.

the three main cloud service models are as follows:

Software as a Service (SaaS)

Think of something like Gmail, the ubiquitous free webmail service. With a SaaS product, the consumer simply accesses the product through their browser and doesn’t have to be concerned with installations or updates. When paid, these services usually are subscription-based.

Platform as a Service (PaaS)

You can think of PaaS offerings as a curated set of services that work together to solve a large business need. For example, a business may want to create a modern microservices-based product, use remote developers, and have the product readily accessible with no delays around the world. A PaaS company will offer a full development environment where the software can be built, tested, and deployed within their predetermined constraints. This frees the customer to focus on the business and creativity of the product, instead of additional concern over infrastructure.

Infrastructure as a Service (IaaS)

IaaS is the public cloud environment at its lowest commoditized levels. The big offerings such as AWS, Azure, and Google Cloud offer their infrastructure’s resources, network connectivity, and security compliance as a product that enterprises can use to customize how they see fit in order to build a cost-optimized software offering.

2.      Differentiate between stack and queue with example?

STACKS	QUEUES
Stacks are based on the LIFO principle, i.e., the element inserted at the last, is the first element to come out of the list.	Queues are based on the FIFO principle, i.e., the element inserted at the first, is the first element to come out of the list.
Insertion and deletion in stacks takes place only from one end of the list called the top.	Insertion and deletion in queues takes place from the opposite ends of the list. The insertion takes place at the rear of the list and the deletion takes place from the front of the list.
Insert operation is called push operation.	Insert operation is called enqueue operation.
Delete operation is called pop operation.	Delete operation is called dequeue operation.
In stacks we maintain only one pointer to access the list, called the top, which always points to the last element present in the list.	In queues we maintain two pointers to access the list. The front pointer always points to the first element inserted in the list and is still present, and the rear pointer always points to the last inserted element.

3.      What are the functionalities of firewall in a network?

A firewall in the networking world should examine the traffic that is entering into the network and pass the “Wall” based on some rules defined by the network and its resources. It acts as a security guard, who normally sits at the main gate, and checks your identity and access privileges and lets you in. Depending on the type of organization, the guards may screen people who are exiting the gate too. Many of the Internet and Information security concepts can be described using some of these practical examples.

If you talk to various vendors about a firewall and its function you will get several different answers or definitions.

In its simplest form, a firewall is a combination of hardware and software devices, which bifurcates the internal network from the outside networks (Internet) and blocks certain traffic and allows some specific traffic. However, it has three basic functions (depending upon its type):

• Packet filtering: A firewall filters the IP packets. The IP headers of all the packets that enter or exit the network firewall are inspected. Firewall makes an explicit decision on each packet that enters as to whether to allow the packet or deny the packet.

• Stateful Packet Filtering: Here the packet filtering goes beyond basic packet filtering. This keeps track of state of connection flows for all the packets, in both directions. It also keeps track of all the IP addresses currently connected at any point of time.

• Application Level Gateways (Proxy): A firewall is also capable of inspecting application level protocols. This requires the firewall to understand certain specific application protocols.

 

4.      Differentiate between client-server network and peer-to-peer network?

BASIS FOR COMAPAISON	CLIENT-SERVER	PEER-TO-PEER
Basic	There is a specific server and specific clients connected to the server.	Clients and server are not distinguished; each node act as client and server.
Service	The client request for service and server respond with the service.	Each node can request for services and can also provide the services.
Focus	Sharing the information.	Connectivity.
Data	The data is stored in a centralized server.	Each peer has its own data.
Server	When several clients request for the services simultaneously, a server can get bottlenecked.	As the services are provided by several servers distributed in the peer-to-peer system, a server in not bottlenecked.
Expense	The client-server are expensive to implement.	Peer-to-peer are less expensive to implement.
Stability	Client-Server is more stable and scalable.	Peer-toPeer suffers if the number of peers increases in the system.

 

5.      Draw a full adder that is made of two half adder and find out the function of output of full adder?

Logical Expression for SUM:
= A’ B’ C-IN + A’ B C-IN’ + A B’ C-IN’ + A B C-IN
= C-IN (A’ B’ + A B) + C-IN’ (A’ B + A B’)
= C-IN XOR (A XOR B)
= (1,2,4,7)

Logical Expression for C-OUT:
= A’ B C-IN + A B’ C-IN + A B C-IN’ + A B C-IN
= A B + B C-IN + A C-IN
= (3,5,6,7)

Another form in which C-OUT can be implemented:
= A B + A C-IN + B C-IN (A + A’)
= A B C-IN + A B + A C-IN + A’ B C-IN
= A B (1 +C-IN) + A C-IN + A’ B C-IN
= A B + A C-IN + A’ B C-IN
= A B + A C-IN (B + B’) + A’ B C-IN
= A B C-IN + A B + A B’ C-IN + A’ B C-IN
= A B (C-IN + 1) + A B’ C-IN + A’ B C-IN
= A B + A B’ C-IN + A’ B C-IN
= AB + C-IN (A’ B + A B’)
Therefore COUT = AB + C-IN (A EX – OR B)

6.      What is the functionality of multiplexer? Draw a 4-to-1 Line multiplexer and its truth table and describe its functionalities.

7.      Draw a flowchart to find out the root of  aX2+bx+c=0 through C/C++ Program.

Code in C++ :

#include <iostream>

#include <cmath>

using namespace std;

int main() {

    float a, b, c, x1, x2, discriminant, realPart, imaginaryPart;

    cout << "Enter coefficients a, b and c: ";

    cin >> a >> b >> c;

    discriminant = b*b - 4*a*c;   

    if (discriminant > 0) {

        x1 = (-b + sqrt(discriminant)) / (2*a);

        x2 = (-b - sqrt(discriminant)) / (2*a);

        cout << "Roots are real and different." << endl;

        cout << "x1 = " << x1 << endl;

        cout << "x2 = " << x2 << endl;

    }  

    else if (discriminant == 0) {

        cout << "Roots are real and same." << endl;

        x1 = (-b + sqrt(discriminant)) / (2*a);

        cout << "x1 = x2 =" << x1 << endl;

    }

    else {

        realPart = -b/(2*a);

        imaginaryPart =sqrt(-discriminant)/(2*a);

        cout << "Roots are complex and different."  << endl;

        cout << "x1 = " << realPart << "+" << imaginaryPart << "i" << endl;

        cout << "x2 = " << realPart << "-" << imaginaryPart << "i" << endl;

    }

    return 0;

}

8.      In which case the “static” keyword is used in case of C++ Programming?

    For class member functions, marking them as static means that the function doesn't need to be called on a particular instance of an object (i.e. it doesn't have a this pointer). Static variables are shared between every instance of a class, instead of each class having their own variable.

9.      Where is used E-R diagram? Draw a E-R diagram that describe many-to-many relationships?

    Database troubleshooting: ER diagrams are used to analyze existing databases to find and resolve problems in logic or deployment. Drawing the diagram should reveal where it's going wrong. Business information systems: The diagrams are used to design or analyze relational databases used in business processes.

Draw a E-R diagram that describe many-to-many relationships

    A many-to-many relationship refers to a relationship between tables in a database when a parent row in one table contains several child rows in the second table, and vice versa. Many-to-many relationships are often tricky to represent.

The many-to-many relationship is usually a mirror of the real-life relationship between the objects the two tables represent.

10.   What is IP address? Write down the differentiate between classful and classless addressing?

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. An IP address serves two main functions: host or network interface identification and location addressing.

Classful Addressing:-

1) In Classful addressing it divides IP address into network ID and host ID

for example Class A :- has first octet as network ID and last three octet as Host ID

Class B :- has first two as network ID and last three two as Host ID

Class C :- has first three as network ID and last  octet as Host ID

2) Here class A,B and C are used where as class D is used for multicasting and class D for research

3) Disadvantage is that it limit the number of network that can be provided to the network

4) Example RIP(Routing Information Protocol) protocol uses classful addressing

5) Class A  :\8 as (1 octet is network ID) , Class B :-\16 , Class C : \24

6) Same Subnet mask is used in complete network

Classless Addressing :-

1) It allows us to use variable length subnet mask so also known as VLSM (Variable Length Subnet Mask)

2) Different subnet mask used in same network.

3) In this there is no boundary on host id and network id

4) Classless Addressing also known as CIDR(classless interdomain routing)

5) There is no default subnet mask in classless routing.

11.  Give the full from of Wi-Fi and WiMAX. Write down the advantages and disadvantages of these.

    WiFi stands for Wireless Fidelity.

    WiMax stands for Wireless Inter-operability for Microwave Access.

    WiFi uses Radio waves to create wireless high-speed internet and network connections.

advantages of WiFi:

➨It is easy to add or move wifi clients or wifi stations to the wifi network created by AP (Access Point).

➨Installation is very quick and easy. It does not require technical knowledge of wifi or wlan system and its protocols.

➨Access to the wifi network can be availed from anywhere within the wifi AP (Access point) coverage range.

➨WiFi enabled USB dongles are available at very affordable rates from TP-Link, D-Link, Tenda etc.

➨Latest wifi standard versions such as 11n and 11ac deliver fast data connection rates e.g. 300 Mbps and higher.

disadvantages of WiFi:

➨Data transfer rate decreases (to individual computer) when number of clients or computers connected with wifi network increases.

➨Full security is difficult to achieve due to wifi connection being wireless in nature. It requires proper security authentication protocols and configurations.

➨Wifi devices operate in full functionality and without any interruptions when they are within the range of AP and receiving good signal strength. WiFi access is limited to about 30 to 100 meters (i.e. 100 to 300 feet).

➨In case wifi connection does not work, minimal troubleshootings are needed. This requires one to understand basics of wifi device from user manual provided by the manufacturer.

12.   What is Polymorphism? Describe it with example?

    In programming languages and type theory, Polymorphism is the provision of a single interface to entities of different types or the use of a single symbol to represent multiple different types.

Function or method overloading and overriding is the great example of Polymorphism. 

 13.   What are the RS-232C & IEEE 1394?

    IEEE 1394, High Performance Serial Bus, is an electronics standard for connecting devices to your personal computer.

14.   Convert B3D8 & 3FC9 to binary and express the sum of these in hexadecimal form.

B3D8= (1011001111011000)2

3FC9=(11111111001001)2

15.   Prove that