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The following are some of the advantages of using Object-Oriented Programming Languages:

• Object-Oriented Programming Languages (OOPLs) take a bottom-up approach to programming, allowing programmers to simulate the real world and its constituents.
• The use of Object-Oriented Programming Languages decreases the quantity of code that programmers write.
• Without compromising other features, code can be readily altered and EXTENDED. Object-Oriented Programming Languages (OOPLs) divide a HUGE problem into smaller chunks.
• The user is not exposed to unnecessary data when abstraction is used.
• Object-Oriented Programming Languages necessitate a lengthy and thorough design phase, resulting in a superior design with fewer flaws.
• It enables the reusability of code.
• Object-Oriented Programming Languages allow programmers to REACH their goals more quickly.

The following are some of the disadvantages of using Object-Oriented Programming Languages:

• In order to employ these languages, a lot of planning is required.
• These are not appropriate for MINOR issues since they lead to overcomplication.
• In Object-Oriented Programming Languages, classes have a propensity to be too broad.
• Programs created in Object-Oriented Programming Languages might take a lot of memory in some cases, which is obviously UNDESIRABLE.

Given below are some of the different types of operating systems:

• BATCH Operating System: This operating system has no direct interaction with the computer. There is an operator who groups related jobs that have the same need into batches. It is the operator's job to group jobs with SIMILAR requirements.
• Distributed Operating Systems (DOS): A distributed operating system (DOS) is software that manages multiple computers as if they were one.
• Network Operating Systems: Computers running different operating systems can connect to a single network using Network Operating Systems. It is frequently utilized for security reasons.
• Time-Sharing Operating System: A time-sharing operating system allows multiple individuals to SHARE computer resources. This type of operating system makes the most of its resources.
• Real-Time Operating Systems (RTOS): These types of operating systems are used in situations when a large number of events, the majority of which are EXTERNAL to the computer system, must be accepted and processed promptly or within a tight deadline. Examples of such applications include industrial control, telephone switching equipment, flight control, and real-time simulations.

The following are some examples of operating systems:

• Microsoft Windows (Graphical User Interface Operating System based for Personal Computers)
• Apple's iOS (iPhone, IPAD, and iPod Touch operating system)
• Apple's personal computers and workstations, such as the MacBook and iMac, run macOS.
• Linux or GNU (for Personal Computers, File and Print server, Workstations, ISP, Three-tier Clients and Servers)
• Android (Google's mobile operating system for smartphones, tablets, smartwatches, and other devices)

The term "Real-Time Operating System" refers to an operating system that is susceptible to real-time limitations, such as ensuring a response within a specified time limit or meeting a specific deadline. A flight control system, for EXAMPLE, or real-time monitoring. The following are the different types of real-time systems having timing constraints:

• Soft Real-Time Operating System: A soft real-time system is one whose performance is impaired if the results do not meet the set timing requirements. In a soft real-time system, fulfilling deadlines is not required for every activity, but the process must be completed and the outcome delivered. Even soft real-time systems cannot miss the deadline for every activity or process, which must meet or miss the deadline BASED on priority. Soft Real-Time Operating Systems include things like PHONE switches.

• Hard Real-Time Operating System: Timelines are treated as a deadline in a hard real-time system, and they should never be overlooked. Because hard real-time systems have no persistent memory, their procedures must be completed correctly the first time. The Hard Real-Time System must produce correct ANSWERS to events in the time allotted. A totally deterministic and time-constrained system is known as a hard real-time system. When tardiness RISES, the usefulness of a hard real-time system's result drops sharply, and it may even become negative. The term "tardiness" describes how late a real-time system completes a task in comparison to the deadline. Consider a flight controller system as an example.

CPU Scheduling is the process of determining which process will have exclusive use of the CPU while another is paused. The basic goal of CPU scheduling is to ENSURE that whenever the CPU is idle, the OS chooses at least one of the programmes in the ready queue to run. The CPU scheduler will be in charge of the selection process. It chooses from among the processes in memory that are ready to run. It simply solves the problem of selecting which of the outstanding requests should be given priority. Its FUNDAMENTAL goal is to alleviate resource scarcity while also ensuring justice among those who use the resources. In layman's terms, it is a method of allocating resources among multiple competing jobs. The various types of Scheduling Algorithms are as follows:

• First Come First Serve (or FCFS)
• Round Robin
• Shortest Time Remaining
• Priority Scheduling
• Multilevel Queue Scheduling
• Shortest Job First

First Come First Serve Scheduling Algorithm:

FCFS (First Come First Serve) is an operating system scheduling technique that executes processes in the order in which they arrive in the Ready Queue of the operating system. To put it another way, the process that comes first will be carried out first. Its nature is non-preemptive. If the burst time of the first process is the longest among all the jobs, FCFS scheduling may generate an issue of HUNGER. The time REQUIRED by the process for execution in MILLISECONDS is referred to as burst time. In comparison to other Operating System scheduling algorithms, it is also considered the easiest and simplest. The FIFO (First In First Out) queue is commonly used to handle FCFS implementation.

Let us look at the FCFS Scheduling Algorithm with the help of an example. Let us assume that there are five processes with process IDs P0, P1, P2, P3, and P4 in the following given schedule. In the ready queue, P0 comes at time 0, P1 arrives at time 1, P2 arrives at time 2, P3 arrives at time 3, and Process P4 arrives at time 4. The processes are listed in the table below, along with their respective Arrival and Burst times.

The following formula is used to compute the turnaround time and the waiting time:

The average waiting time is calculated by adding all of the processes' respective waiting times and dividing the total by the total number of processes. Therefore we can say that the average Waiting time is 31/5 units = 6.2 units. Given below is the Gnatt Chart for the entire FCFS algorithm.

Demand paging in Operating Systems is a technique for loading pages (In a virtual memory operating system, a page is the smallest unit of data for memory management. A page frame is the smallest fixed-length contiguous unit of physical memory into which the operating system maps memory pages) into memory only when they are needed. Virtual Memory is a storage allocation system that allows secondary memory to be addressed as if it were the main memory. The addresses used by a program to refer to memory are distinct from the addresses used by the memory system to designate physical storage sites, and program generated addresses are automatically translated to machine addresses. The capacity of virtual storage is limited by the computer system's addressing METHOD, and the amount of secondary memory available is determined by the number of main storage sites available rather than the actual number of main storage locations.

A page is only brought into memory in this case when a position on the page is addressed during execution. In general, the steps for bringing a page into the main memory or demand paging are as FOLLOWS:

• The operating system makes an attempt to access the page.
• The CPU continues PROCESSING instructions as usual if the page is valid (in memory).
• A page FAULT trap is done by the operating systems when a page is incorrect.
• The operating system then checks to see if the memory reference is a legitimate reference to a secondary memory location. If this is not the case, the process will be terminated (illegal memory access). The operating system will have to READ the page in the main memory otherwise.
• To read the desired page into the main memory, the operating system schedules a disc operation.
• After that, the operation that was halted due to the operating system trap is restarted or continued.

A Bootstrap Program is usually a program that initializes the operating system during the startup of the computer system, that is, the first program that is run when a computer system boots up. The operating system is loaded using a METHOD or application known as booting. Overall, the performance and functionality of the operating system are solely dependent on the bootstrap PROGRAMME. It is entirely stored on the disc in boot blocks at a certain location. It also locates and loads the kernel into the main memory, after which the program begins to run. 

As we can SEE in the image GIVEN below, the Bootstrap Program resides in the Read-Only Memory (ROM) of our COMPUTERS and they are the ones to first read the Operating Systems and load it into the RAM (Random Access Memory) of our computers. Only after that, the operating systems can start other devices of the computer like the Graphics cards, keyboards, mouses, etc.

The process of communicating information among the servlets of a JAVA web application is known as SERVLET collaboration. Method invocations allow information to be sent from one servlet to another. The Servlet API (Application Programming Interface) of Java is the primary method for achieving Servlet Collaboration, and it exposes two INTERFACES.

• javax.servlet.RequestDispatcher
• javax.servlet.http.HttpServletResponse

These two interfaces include the methods for achieving the purpose of servlet information SHARING.

In Relational Algebra, one operand OPERATIONS are known as unary operations. The procedures PROJECTION, SELECTION, and RENAME are unary operations in relational algebra:

• The SELECT operation: The SELECT operation SELECTS a subset of tuples from a relation that fulfils a set of criteria. The SELECT operation is a FILTER that keeps only those tuples that fulfil a set of criteria. Alternatively, you MAY use the SELECT method to limit the tuples to those that fulfil the criteria. The SELECT operation can be thought of as dividing the relation horizontally into two groups of tuples: those that meet the criteria and are selected, and those that do not and are rejected.
• The PROJECT operation: If a relation is viewed as a table, the SELECT operation selects certain rows while discarding others. In contrast, the PROJECT operation selects a subset of the table's columns while rejecting the remainder. We can use the PROJECT operation to project a relation over just a few of its attributes if we're just interested in a few of them. As a result, the result of the PROJECT operation can be viewed as a vertical partition of the relation into two relations: one with the needed columns (attributes) and the operation's result, and the other with the rejected columns.
• The RENAME operation: It is occasionally SIMPLE and suitable to break a complicated chain of operations and rename it as a relation with new names. Renaming a relationship can be done for a variety of reasons, including:
  • It is possible that we'll want to save a relation as the result of a relational algebra expression.
  • It is possible that we'll want to join a relation to itself.

In C or C++, an inline function is a function that is declared using the keyword "inline." It has two FUNCTIONS:

• It is a compiler DIRECTIVE that requests that the compiler replace the body of the function inline by performing inline expansion, that is, placing the function code at the location of each function call, thus reducing the overhead of a function call (it is not mandatory for the compiler to comply with the request of the inline function). In this WAY, it is analogous to the register storage class specifier, which also provides an optimization indication. For frequent calls to the same function, inline functions are typically employed.
• The keyword "inline" has a second goal: to change the behaviour of links. The C/C++ separate compilation and linkage architecture requires this, in part because the function's definition (body) must be reproduced in all translation units where it is used to allow inlining during compilation, which causes a collision during linking if the function has external linkage (it violates uniqueness of external symbols). C and C++ (as well as dialects such as GNU C and Visual C++) handle this in different ways.

Given below is an example to understand inline functions in a better way:

Let us assume that the above inline function is called at someplace in the main function of our C program as SHOWN below:

Note that the "multiplyNums(i, j);" function call will be replaced by the following piece of code in the main function itself by the C compiler:

Data INDEPENDENCE is a notion that states that changes in data at one level of a three-tier DataBase Management SYSTEM DESIGN should not affect data at another level. There are two types of data independence:  Physical data independence and Conceptual data independence.

• Physical Data Independence: Any change in the physical location of tables and indexes should have no impact on the conceptual level or the external DISPLAY of data, according to Physical Data Independence. The majority of Database Management Systems offer this data independence, which is straightforward to establish.
• Conceptual Data Independence: Data at the conceptual and external levels must be independent, according to Conceptual Data Independence. Any changes to the conceptual schema should have no effect on the external schema. Changing the appearance of a table by adding or removing features, for example, should have no impact on the user's view of the table. This type of independence, however, is more DIFFICULT to accomplish than physical data independence since changes in conceptual schema are mirrored in the user's view.

DNS is an acronym for Domain Name System. In 1983, Paul Mockapetris and Jon Postel created DNS. It is a naming system that encompasses all internet resources, including physical nodes and applications and is USED to quickly locate resources on a network. The Domain Name System (DNS) is an internet service that translates domain names to IP addresses. Users who don't have DNS MUST know the IP ADDRESS of the website they want to visit.

The working of a Domain Name System: If you wish to go to the "InterviewBit" website, type "HTTPS://www.interviewbit.com" into the address bar of your web browser. Once the domain name is entered, then the domain name system will translate the domain name into the IP address which can be easily interpreted by the computer. Using the IP address, the computer can locate the web page requested by the USER.

The following are some of the advantages of employing views in a database management system:

• A view can REPRESENT a subset of a table's data. As a result, a view can limit the extent to which the underlying tables are visible to the outside world: for example, a user may be ABLE to QUERY the view but not the entire base database.
• Views are aggregated tables in which the database engine aggregates data (sum, average, and so on) and shows the resulting results alongside the data.
• Using views, we may merge and simplify several tables into a single virtual table.
• Views take up very little storage SPACE; the database just stores the view's specification, not a copy of all the data it displays.
• The COMPLEXITY of data can be obscured by views.
• Views can provide additional protection depending on the SQL engine being used.

Network dependability refers to the network's capacity to perform the requested operation through a network, such as communication. In order for a network to function WELL, it must be reliable. The network monitoring SYSTEMS and devices are necessary for the network to be reliable. The network monitoring system detects network faults, while network devices ensure that data reaches its intended destination.

The following factors can be used to assess a network's reliability:

• Downtime: Downtime is defined as the AMOUNT of time it TAKES for a network to recover.
• Failure Frequency: This is the number of times a network fails to work as anticipated.
• Catastrophe: It means that the network has been hit by an unforeseen incident, such as a fire or an earthquake.

When we TRY to connect to any website, for instance, when we try to visit www.facebook.com the FOLLOWING steps take place:

• The browser cache is first checked to see if the content is fresh and whether it is present in the browser cache or not. If it is present in the browser cache, then it is displayed.
• If not present in the browser cache, the browser checks if the URL's IP address is in the cache (browser and OS), and if it is not, it asks the Operating System to perform a DNS (DOMAIN Name System) search using UDP (USER Datagram Protocol ) to obtain the URL's (Uniform Resource Locator) associated IP address from the DNS server, and then establishes a new TCP connection.
• Three-way handshaking establishes a new TCP connection between the browser and the server.
• The TCP connection is used to send an HTTP request to the server.
• The web servers on the Servers process HTTP requests and respond with HTTP responses.
• The browser decodes the server's HTTP answer and decides whether to close or reuse the TCP connection for future requests.
• If the data in the RESPONSE is cacheable, browsers will save it.
• The response is decoded by the browser.

The four LAYERS of the TCP/IP model in Computer NETWORKS are as follows:

• APPLICATION LAYER: The application layer is where you will FIND all of the higher-level procedures.
• Transport Layer: The Transport Layer performs almost identically to the OSI transport layer. It allows peer entities on the network to converse with one another.
• Internet Layer: The Internet Layer is the most critical layer that keeps the entire system together is the internet layer. It sends IP packets where they are supposed to go.
• Network Access Layer or Link layer: To suit the needs of the connectionless internet layer, this layer determines which connectivity, such as serial lines or traditional Ethernet, must be employed.

The following are some of the benefits of using a VPN:

• When compared to Wide Area Network CONNECTIONS, VPN is used to connect OFFICES in different geographical locations remotely.
• VPNs are used to safeguard transactions and move secret data between workplaces in different parts of the world.
• By using virtualization, a VPN protects an organization's information safe from any potential threats or invasions.
• VPN encrypts internet traffic and hides the user's identity ONLINE.

A virtual private network (VPN) extends a private network across a public network, allowing users to send and receive data as if their computers were physically linked to the private network. Increased functionality, security, and control of the private network are all advantages of using a VPN. It is frequently used by telecommuting workers to gain access to resources that are not available on the public network. Although encryption is widespread, it is not a requirement of a VPN connection. A VPN is formed by using dedicated circuits or tunnelling technologies to build a virtual point-to-point connection over existing networks. Some of the benefits of a wide area network can be obtained using a VPN accessible via the public Internet (WAN). The resources provided within the private network can be ACCESSED remotely from the user's perspective.

The different types of VPNS are as follows:

• Access VPN: Access VPN is a type of virtual private network that allows remote mobile users and telecommuters to connect to the internet. It can be used as a substitute for dial-up or ISDN (Integrated Services DIGITAL Network) connections. It is a low-cost option with a wide range of connectivity options.
• Site to Site VPN: A Site to Site VPN, also known as a Router to Router VPN, is a type of virtual private network that connects the networks of two offices in different locations. As LISTED below, there are two subcategories:
  • Intranet VPN: An intranet VPN connects remote offices in different geographic areas using common infrastructure (internet connectivity and servers) and the same accessibility policies as a private WAN (wide area network).
  • Extranet VPN: Extranet VPN connects intranet users, suppliers, consumers, partners, and other entities via dedicated connections using shared infrastructure.

A class with abstract METHODS is known as an abstract class. ALTHOUGH these methods are declared, they are not defined in the abstract classes. If these methods are to be utilized in a subclass, they must be SPECIFIED in that subclass solely.

No, we cannot create objects or instances of abstract classes. Because an abstract class lacks a complete implementation, no instances can be PRODUCED. It is possible to build instances of subclasses that INHERIT the abstract class.

The key DIFFERENCES between an abstract class and an interface are as follows:

Some of the limitations of inheritance are as follows:

• Jumping back and forth between DIFFERENT CLASSES LENGTHENS the time and effort required to complete a program.
• The parent and child classes become inextricably linked.
• Any changes to the program would necessitate changes in both the parent and child classes.
• It necessitates careful IMPLEMENTATION or ELSE, wrong results will follow.

The key differences between Object-Oriented Programming  (OOP) and Structure Oriented Programming  (SOP) are as FOLLOWS: