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MCA Articles
Page 4 of 94
Protection and Security in Operating System
Protection and security requires that computer resources such as CPU, softwares, memory etc. are protected. This extends to the operating system as well as the data in the system. This can be done by ensuring integrity, confidentiality and availability in the operating system. The system must be protect against unauthorized access, viruses, worms etc. Threats to Protection and Security A threat is a program that is malicious in nature and leads to harmful effects for the system. Some of the common threats that occur in a system are − Virus Viruses are generally small snippets of code embedded in a ...
Read MoreDifference between LAN, MAN and WAN
When several computers are connected together and are able to communicate with one another, it is called a computer network. Computer networks are designed to share data and information among the computers of the network. Depending on the operating geographical area, computer networks are of the three major types, namely LAN, MAN, and WAN. All the three computer networks are designed for the same purpose, i.e., for sharing information among the computers. But, they are different in many ways, which we are going to highlight in this article. Let's start with some basics of LAN, MAN, and WAN. What ...
Read MoreDifference between Private and Public IP addresses
What is an IP Address? An IP address (Internet Protocol address) is a numerical identifier, such as 192.0.2.1, that is associated with a computer network that communicates using the Internet Protocol. An IP address is used for two purposes: identifying a host or network interface, and addressing a specific location. An IP address has two primary functions: it identifies the host, or more particularly its network interface; and it indicates the host's position in the network, allowing a path to be established to that host. IP addresses can be either Public or Private. Read through this article to ...
Read MoreExtended Entity-Relationship (EE-R) Model
EER is a high-level data model that incorporates the extensions to the original ER model. Enhanced ERD are high level models that represent the requirements and complexities of complex database.In addition to ER model concepts EE-R includes −Subclasses and Super classes.Specialization and Generalization.Category or union type.Aggregation.These concepts are used to create EE-R diagrams.Subclasses and Super classSuper class is an entity that can be divided into further subtype.For example − consider Shape super class.Super class shape has sub groups: Triangle, Square and Circle.Sub classes are the group of entities with some unique attributes. Sub class inherits the properties and attributes from ...
Read MoreError-Detecting Codes - Checksums
Errors and Error DetectionWhen bits are transmitted over the computer network, they are subject to get corrupted due to interference and network problems. The corrupted bits leads to spurious data being received by the receiver and are called errors.Error detection techniques are responsible for checking whether any error has occurred or not in the frame that has been transmitted via network. It does not take into account the number of error bits and the type of error.For error detection, the sender needs to send some additional bits along with the data bits. The receiver performs necessary checks based upon the ...
Read MoreWhat are data link layer design issues?
The Data Link layer is located between physical and network layers. It provides services to the Network layer and it receives services from the physical layer. The scope of the data link layer is node-to-node.The following are the design issues in the Data Link Layer −The services that are provided to the Network layer.FramingError controlFlow controlServices to the Network LayerIn OSI each layer uses the services of the bottom layer and provides services to the above layer. The main function of this layer is to provide a well defined service interface over the network layer.Types of ServicesThe services are of ...
Read MoreDifferences between Pure Aloha and Slotted Aloha
The Aloha Protocol allows several stations to send data frames over the same communication channel at the same time. This protocol is a straightforward communication method in which each network station is given equal priority and works independently.Aloha is a medium access control (MAC) protocol for transmission of data via a shared network channel. Using this protocol, several data streams originating from multiple nodes are transferred through a multi-point transmission channel.There are two types of Aloha protocols − Pure Aloha and Slotted Aloha.In Pure Aloha, the time of transmission is continuous. Whenever a station has an available frame, it sends ...
Read MoreWhat are Routers in Computer Network?
Routers are networking devices operating at layer 3 or a network layer of the OSI model. They are responsible for receiving, analysing, and forwarding data packets among the connected computer networks. When a data packet arrives, the router inspects the destination address, consults its routing tables to decide the optimal route and then transfers the packet along this route.Features of RoutersA router is a layer 3 or network layer device.It connects different networks together and sends data packets from one network to another.A router can be used both in LANs (Local Area Networks) and WANs (Wide Area Networks).It transfers data ...
Read MoreWhat are Hub and Switch in Computer Network?
HubsA hub is a physical layer networking device which is used to connect multiple devices in a network. They are generally used to connect computers in a LAN.A hub has many ports in it. A computer which intends to be connected to the network is plugged in to one of these ports. When a data frame arrives at a port, it is broadcast to every other port, without considering whether it is destined for a particular destination or not.SwitchesA switch is a data link layer networking device which connects devices in a network and uses packet switching to send and ...
Read MoreDifferent types of system calls
The interface between a process and an operating system is provided by system calls. In general, system calls are available as assembly language instructions. They are also included in the manuals used by the assembly level programmers.System calls are usually made when a process in user mode requires access to a resource. Then it requests the kernel to provide the resource via a system call.Types of System CallsThere are mainly five types of system calls. These are explained in detail as follows −Here are the types of system calls −Process ControlThese system calls deal with processes such as process creation, ...
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