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Polymorphism in Object-Oriented Programming is defined as the presence of several forms. It is made up of two words: "POLY" which means many and "morph" which means FORM. Its behaviour varies depending on the situation. When we have numerous CLASSES that are related to each other by inheritance, this happens. Consider a base class named car, which has a method called carBrand(). VOLKSWAGEN, Ferrari, BMW and Audi are examples of derived automobile classes, and each has its own implementation of a car. In C++, there are two types of polymorphism:

• Compile TIME Polymorphism or Static Polymorphism.
• Runtime Polymorphism or Dynamic Polymorphism.

The key differences between Relational Database Management SYSTEMS (RDBMS) and Database Management Systems (DBMS) are as follows:

The transparent Distributed Database Management System is a TYPE of database management system that hides the physical structure of the database from USERS. Physical structure, also known as physical storage structure, REFERS to the memory MANAGER of a database management system and describes how data is SAVED on a disk. There is less abstraction as a result of this. In Distributed Database Management Systems (or DDBMS), there are four forms of transparency:

• Transparency in transactions
• Transparency in distribution
• Transparency in performance
• Transparency in relational databases.

The following are some of the BENEFITS of a DATABASE management SYSTEM:

• It aids in the management of database redundancy.
• Ensures that data is consistent.
• Easily accessible.
• Backup and recovery services are available.
• Integrity limitations are enforced.
• It puts a stop to UNAUTHORIZED access.
• Multiple USER interfaces are available.
• Due to the usage of queries, data extraction and processing are simple.

A star topology is a type of computer network that USES the spoke hub distribution concept. In a star network, each host is connected to a central hub. In its most basic form, one single hub acts as a ROUTE for messages. The star network is one of the most common computer network architectures.

The following are some of the advantages of star topology:

• It is easy to analyze, set up, and modify.
• The nodes that have failed are the only ones that are affected. Other nodes are still up and running.
• Fast performance is attainable with a small number of nodes and little network traffic.
• In a Star topology, ADDING, removing, and transferring devices is straightforward.

The following are some of the disadvantages of star topology:

• If the Hub or CONCENTRATOR fails, the attached nodes are disabled.
• The cost of establishing a star topology is substantial.
• Heavy network traffic might cause buses to slow down dramatically.
• Performance is determined on the Hub's capacity.
• The network could be brought down by a faulty cable or a lack of suitable termination.

The differences between the SLIP and Point-to-Point protocol are given below:

SLIP is an acronym for Serial Line Internet Protocol. It is basically a TCP/IP based fundamental protocol that is used for communication through serial ports and routers. They allow machines to connect with one another that was previously configured for direct communication. 

For example, a customer COULD be connected to the Internet Service Provider (ISP) over a slower SLIP line. When a client needs a service, he or she contacts the ISP and makes a request. The ISP responds to the request by sending it to the Internet on high SPEED multiplexed lines. The Internet Service Provider then sends the results back to the client over SLIP lines. A SLIP frame has a straightforward format, CONSISTING of a payload and a flag that serves as an END delimiter. A special character with a decimal value of 192 is commonly used as the flag. If this flag is present in the data, it is preceded by an ESCAPE sequence that prevents the receiver from interpreting it incorrectly.

The key differences between TCP and UDP are highlighted in the table given below:

IP security (IPSec) is a set of protocols developed by the Internet Engineering Task Force (IETF) to provide data authentication, integrity, and CONFIDENTIALITY between two communication points over an IP network. It also specifies the encryption, decryption, and authentication of packets. It defines the protocols for secure key management and key exchange.

It is MADE up of the following components:

• Encapsulating Security Payload (ESP): Data integrity, encryption, authentication, and anti-replay are all supplied by the Encapsulating Security Payload (ESP). Payload authentication is also supported.
• Header of Authentication (AH): Data integrity, authentication, and anti-replay are also supported by this header, but not encryption. Unwanted packet transmission is protected by anti-replay protection. It does not guarantee data privacy.
• IKE (Internet Key Exchange): IKE (Internet Key Exchange) is a network security protocol that allows two devices to communicate across a Security Association by dynamically exchanging encryption keys (SA). The Security Association (SA) creates common security features between two network entities to facilitate secure communication. IKE (Internet Key Exchange) secures message content and provides an open framework for implementing standard algorithms such as SHA and MD5. The IP sec users of the technique assign a UNIQUE IDENTIFIER to each packet. Using this identifier, the device can assess whether a packet is correct or not. Unauthorized packets are discarded and do not reach their intended receiver.

A program slice is a collection of statements from a program. If we wanted to build software in terms of compatible slices, we could code a slice and test it right away. We can then code and test more slices before putting them together into usable software. This PROCEDURE is known as slice splicing.

Static and dynamic slicing are the two types of slicing:

• Slicing in a static state: A static slice of a program is MADE up of all statements that have the potential to modify the VALUE of a variable at any time during the program's execution. Static slices are, on average, bigger. It takes into account every possible programme execution scenario.
• Dynamic Slicing: A dynamic slice of a program is made up of all the statements that affect the value of a variable at any given time throughout the program's execution. Dynamic slices are, on average, SMALLER. It only takes into consideration the execution of a single program.

A UNION is a special data type in C that lets you STORE many data types in the same memory space. Although a union can have many members, only one of them has worth at any given time. Unions are a good way to reuse the same memory space for several tasks.

The syntax of unions in C programming is given below:

An example of unions in C programming is given below:

A structure or struct in C programming is a user-defined data type that lets us mix data ITEMS of a lot of TYPES. A structure is basically used to represent a record.

The syntax of structs in C programming is given below:

An example of structs in C programming is given below:

Storage Classes are used to define the properties of a variable or function. SCOPE, visibility, and longevity are all qualities that allow us to track the presence of a variable during the execution of a programme. There are four storage classes in the C programming language:

• Auto: This is the default storage class for all variables specified inside a function or a block. Auto variables can only be utilized within the block/function in which they were defined; they can't be used outside (which defines their scope). They can, however, be accessed outside of their scope by using pointers, which point to the memory address where the variables are kept. They are given a garbage value by default whenever they are declared.
• Static: Static variables are often used in C language programs, and this storage type is used to declare them. Even after they have been removed from their scope, static variables can keep their value! As a result, we MAY assert that they are only initialized once and live only till the programme terminates. No fresh memory is allocated because they are not declared again. They have a limited scope that is restricted to the role they have been allocated. Global static variables in the programme can be accessed from anywhere in the code. By default, the compiler assigns a value of 0 to these.
• Register: This storage class declares register variables, which are functionally comparable to auto variables. The only difference is that if there is a free registration available, the compiler will attempt to store these variables in the CPU's register. If no free REGISTERS are available, the data is kept in memory alone. The register keyword is used to create a few variables that will be accessed frequently in a programme, hence speeding up its execution. A register variable's address cannot be accessed via pointers, which is an important fact to note.
• Extern: The storage class extern merely means that the variable is defined outside of the block in which it is referenced. In essence, the value is ASSIGNED to it in another block, which can then be overwritten/changed in another block. Any function or block can make a regular global variable extern by using the 'extern' keyword before its declaration or definition. This INDICATES that instead of establishing a new variable, we're simply accessing and using the global variable. The extern keyword can be used to extend the visibility of variables and functions. Because functions are visible throughout the programme by default, the use of extern in function declarations or definitions is unnecessary. Its use is self-evident. When you use extern to declare a variable, you are not actually defining it.

STRUCTURED PROGRAMMING is a programming paradigm in which the control flow is completely structured. A structure is a block that has a set of RULES and has a DEFINED control flow, such as (if/then/else), (while and for), block structures, and subroutines. Nearly all programming paradigms, including the Object-Oriented Programming model, require structured programming.

A copy constructor is a member function that uses another object of the same CLASS to initialize an object. Our copy constructor can be defined by us. If no copy constructor is defined, the DEFAULT copy constructor is used.

The above-mentioned code snippet shows how the copy constructor is used to define the object "obj2" using the already existing object "obj1".

Macros in C/C++ are constants in the preprocessor that are replaced at compile time. As a result, a macro is a named block of code within a programme. When the COMPILER detects this NAME, it replaces it with the actual piece of code. The disadvantage of macros is that they are not function calls, but RATHER code CHANGES. Similarly, when substituting the identical values, they have the advantage of saving time.

In the sample code snippet given below, all instances of the phrases TEXT, EVEN, and SUMMATION will be replaced with whatever is in their body.

The following are the several types of MEMORY spaces allocated by the Java Virtual Machine:

• The Class(Method) Area: The Class(Method) Area keeps TRACK of per-class structures such as the RUNTIME constant pool, fields, method data, and method code.
• Program COUNTER (PC) Register: The PC (program counter) register stores the address of the Java virtual machine instruction CURRENTLY being executed.
• Stack: Frames are kept in the Java Stack. Local variables and partial results, as well as invoking and returning methods, are all managed by it. Each thread has its own JVM stack, which is created at the same time as the thread. A new frame is created each time a method is called. When the method invocation of a frame is complete, it is destroyed.
• The Native Method Stack: The Native Method Stack contains every single native method utilized in the application.
• Heap: This is where the objects' memory is allocated during runtime.

Socket programming is a technique for allowing two network nodes to communicate. One socket (node) listens for traffic on a specified port at a specific IP address, while the other socket connects to it. The listener socket is created by the server while the CLIENT is connected to it.

Some advantages of Java Sockets are as follows:

• Sockets are versatile and sufficient. Socket based programming is straightforward to implement for ordinary communications.
• Sockets are to blame for low network traffic. Unlike HTML forms and CGI scripts, which construct and send entire web pages for each new request, Java applets can simply send the changed information.

Some disadvantages of Java Sockets are as follows:

• Security CONSTRAINTS can be burdensome at times because a Java applet running in a Web BROWSER can only connect to the machine from which it came and nowhere else on the network.
• Socket based connections, despite all of Java's advantages, are LIMITED to the delivery of raw data packets between programs. Both the client and the server must provide mechanisms for turning the data into something useful.
• Because data formats and protocols are application-specific, socket-based systems are limited in their reusability.

The Java Virtual Machine's CLASSLOADER subsystem is in charge of loading class FILES. When we execute a Java application, the classloader loads it first.

The following are Java's three built-in classloaders:

• ClassLoader in Bootstrap: ClassLoader is the superclass of Extension classloader, which is the DEFAULT classloader in Bootstrap. It loads the rt.jar file, which contains all Java Standard Edition class files, including java.lang, java.net, java.util, java.io, and java.sql.
• Extension ClassLoader: This is the PARENT of SYSTEM ClassLoader and the child of Bootstrap ClassLoader. The $JAVA_HOME/jre/lib/ext directory's jar files are loaded.
• System or Application ClassLoader: System or Application ClassLoader is the child classloader of Extension ClassLoader. The classpath is used to load the class files. By default, the classpath is set to the current directory. To change the classpath, use the "-cp" or "-classpath" switches.

A few functionalities of Operating Systems are as follows:

• Provides a user interface: Operating systems serve as a link between computer hardware and the people who use it. It allows the user to access the hardware in a methodical fashion.
• File Management: To make navigation and usage more effective, a file system is organized into directories. These directories may include additional directories and files. AMONG other things, the operating system keeps track of where data is stored, user access settings, and the condition of each file.
• Security: Password protection and other security features are used by the operating system to protect user data. It also guards against UNAUTHORIZED access to PROGRAMMES and user data.
• Maintains system performance: By keeping an eye on the overall health of the system, it might help you get more out of it. Keep track of the time between service requests and system RESPONSES to get a complete picture of the system's health. This can help with performance by providing important information for debugging.
• Memory Management: The operating system is in charge of the primary memory, also known as main memory. The main memory is made up of a large number of bytes or words, each with its own address. Main memory is a type of fast storage that the CPU can directly access. Before a programme can be executed, it MUST first be loaded into the main memory. An operating system manages memory by performing the following tasks:
  • It keeps track of primary memory, that is, which user programmes use specific memory bytes. Memory addresses that have already been assigned as well as those that have not yet been used.
  • In multiprogramming, the OS sets the order in which processes are allowed memory access and for how long. When a process requests memory, it is allocated, and memory is released when the process quits or performs an I/O activity.
• Error detection: The operating system continuously monitors the system in order to detect errors and keep the machine from failing.
• Device Management: Drivers are used by an operating system (OS) to handle device connectivity. It keeps track of all of the system's connected gadgets. The Input/Output controller is a programme that manages all of the devices in the system. Determines which processes and for how long are permitted access to a device. Devices are distributed in an effective and efficient manner. A device gets deallocated when it is no longer required.
• Processor Management: The operating system determines the order in which processes access the processor and the amount of processing time each process has in a multiprogramming environment.

Schedulers are specialized computer programs that control the scheduling of processes in various ways. Their main task is to decide which jobs to enter into the system and which processes to conduct.

The three types of schedulers are as follows:

• Long Term Scheduler: A job scheduler is another name for a long term scheduler. Which applications are admitted for processing into the system is determined by a long term scheduler. It selects processes from the ready queue and loads them into memory before executing them. The process is loaded into memory for CPU scheduling. The basic purpose of the job scheduler is to deliver a well-balanced mix of jobs, such as Input and Output and CPU bound workloads. It also controls the AMOUNT of MULTIPROGRAMMING done. The AVERAGE rate of process formation must be equal to the average rate of process departure from the system if the degree of multiprogramming remains constant.
• Medium Term Scheduler: This TYPE of scheduler is used to swap programmes in the main memory. It frees up the RAM that the processes have used up. As a result, the degree of multiprogramming is minimized. The medium-term scheduler is in charge of the swapped out processes.
• Short Term Scheduler: A CPU scheduler is another name for a short term scheduler. Its main purpose is to increase system performance in ACCORDANCE with the stated set of criteria. It is the shift from the ready to the running stage of a process. The CPU scheduler selects a process from among those that are ready to run and gives it CPU time. Short term schedulers, often known as dispatchers, choose the next process to run.

The operating system occupies a portion of memory in a multiprogramming computer, while the rest is used by many processes. Memory management is the practice of dividing memory across many operations. Memory management is an operating system approach for coordinating actions between main memory and DISC during the EXECUTION of a task. The PRIMARY goal of memory management is to maximize memory use.

Memory Management  is necessary because of the following reasons:

• Before and after the process, allocation and deallocation of memory are needed.
• To keep track of how much memory is being CONSUMED by processes.
• To keep fragmentation to a minimum.
• To make the best use of the main memory.
• To keep data safe while a process is RUNNING.

A thread is a path of execution within a process. A process can have several threads. Within a process, it's a separate control flow. It consists of a CONTEXT and a series of instructions that must be followed. Threads in the same process use shared memory space. Because threads aren't truly independent of one another, they share their CODE, data, and OS resources with other threads (like open FILES and signals).

The following are the main benefits of using threads in Operating Systems:

• A separate communication system is not required.
• Threads simplify software structure and IMPROVE readability.
• Threads have a faster context switching time (time to switch from one thread to another) than processes.
• The system gets more efficient as FEWER system resources are used.

The following are the most significant drawbacks of using threads:

• Because threads are part of a single process, they cannot be reused.
• They interfere with the address space of their process.
• They require synchronization for concurrent read and write memory access.

The practice of TEMPORARILY storing data so that it can be used and processed by a device, software, or system is known as spooling. Data is supplied to and stored in memory or other volatile storage until a programme or computer requests it for execution. "Simultaneous Peripheral Operations Online" is an acronym for Spooling. The spool is typically stored in PHYSICAL memory, BUFFERS, or interrupts for Input and Output devices on the computer. To process the spool in ascending order, the FIFO (first in, first out) approach is employed. Spooling is the collection and storage of data from many Input and Output activities in a buffer. Input and Output devices can access this buffer, which is a piece of memory or hard disc. In a distributed context, an operating system performs the following tasks:

• Data spooling for Input and Output devices with varying data access rates is handled.
• Maintains the spooling buffer, which acts as a temporary data storage region while the slower device catches up.
• The spooling process maintains parallel computing because a computer can do input and output in parallel order. It is now possible for a computer to simultaneously read data from a tape, write data to disc, and print data to a tape printer.

The most obvious application of spooling is in Printing. Before being added to the printing QUEUE, the printed papers are held in the SPOOL. Several programmes can run and use the CPU during this period without having to wait for the printer to finish printing each page individually. Many additional features, such as setting priorities, receiving notifications when the printing process is complete, and selecting different types of PAPER to print on based on the user's preferences, can be added to the Spooling printing process.

Virtual Memory is a storage allocation method that lets you address SECONDARY memory as if it were the main memory. Program-generated ADDRESSES are automatically converted to machine addresses, which are different from the addresses used by the memory system to designate PHYSICAL storage places. The QUANTITY of secondary memory available is defined by the number of main storage sites available rather than the actual number of main storage locations, and the capacity of virtual storage is restricted by the computer system's ADDRESSING scheme.