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MCA Articles
Page 3 of 94
Three Level Architecture of Database
The ANSI-SPARC database architecture is the basis of most of the modern databases.The three levels present in this architecture are Physical level, Conceptual level and External level.The details of these levels are as follows −Physical LevelThis is the lowest level in the three level architecture. It is also known as the internal level. The physical level describes how data is actually stored in the database. In the lowest level, this data is stored in the external hard drives in the form of bits and at a little high level, it can be said that the data is stored in files ...
Read MoreSubclasses, Superclasses, and Inheritance
The Enhanced Entity Relationship Model contains all the features of the Entity Relationship model. In addition to all that, it also contains features of Subclasses, Superclasses and Inheritance.All of these in detail are as follows −SubclassesA subclass is a class derived from the superclass. It inherits the properties of the superclass and also contains attributes of its own. An example is:Car, Truck and Motorcycle are all subclasses of the superclass Vehicle. They all inherit common attributes from vehicle such as speed, colour etc. while they have different attributes also i.e Number of wheels in Car is 4 while in Motorcycle ...
Read MoreWide Area Network (WAN)
A wide area network (WAN) is a computer network that covers a large geographical area comprising a region, a country, a continent or even the whole world. WAN includes the technologies to transmit data, image, audio and video information over long distances and among different LANs and MANs.The distinguishing features of WAN areWANs have a large capacity, connecting a large number of computers over a large area, and are inherently scalable.They facilitate the sharing of regional resources.They provide uplinks for connecting LANs and MANs to the Internet.Communication links are provided by public carriers like telephone networks, network providers, cable systems, ...
Read MoreDifference between Circuit Switching and Packet Switching
Circuit SwitchingCircuit Switching is a connection-oriented service. It provides a dedicated path from the sender to the receiver. In-circuit switching, a connection setup is required to send and receive data. It has very little chance of data loss and error due to the dedicated circuit, but a lot of bandwidth is wasted because the same path cannot be used by other senders during a congestion. Circuit switching is completely transparent; the sender and receiver can use any bit rate format or framing method.Advantages of Circuit SwitchingIt uses a fixed bandwidth.A dedicated communication channel increases the quality of communication.Data is transmitted ...
Read MoreNetwork Devices (Hub, Repeater, Bridge, Switch, Router, Gateways and Brouter)
Network devices or networking hardware are the physical devices that are used for establishing connections and facilating interaction between different devices in a computer network. Hub Hubs work in the physical layer of the OSI model. A hub is a device for connecting multiple Ethernet devices and making them act as a single network segment. It has multiple inputs and output ports in which a signal introduced at the input of any port appears at the output of every port except the original incoming port. A hub can be used with both digital and analog data. Hubs do not perform ...
Read MoreCut Set and Cut Vertex of Graph
Whether it is possible to traverse a graph from one vertex to another is determined by how a graph is connected. Connectivity is a basic concept in Graph Theory. Connectivity defines whether a graph is connected or disconnected.ConnectivityA graph is said to be connected if there is a path between every pair of vertex. From every vertex to any other vertex, there should be some path to traverse. That is called the connectivity of a graph. A graph with multiple disconnected vertices and edges is said to be disconnected.Cut VertexLet 'G' be a connected graph. A vertex V ∈ G ...
Read MoreFiber Distributed Data Interface (FDDI)
Fiber Distributed Data Interface (FDDI) is a set of ANSI and ISO standards for transmission of data in local area network (LAN) over fiber optic cables. It is applicable in large LANs that can extend up to 200 kilometers in diameter. Features FDDI uses optical fiber as its physical medium. It operates in the physical and medium access control (MAC layer) of the Open Systems Interconnection (OSI) network model. It provides high ...
Read MoreMultiple Access Protocols in Computer Networks
Multiple access protocols are a set of protocols operating in the Medium Access Control sublayer (MAC sublayer) of the Open Systems Interconnection (OSI) model. These protocols allow a number of nodes or users to access a shared network channel. Several data streams originating from several nodes are transferred through the multi-point transmission channel. The objectives of multiple access protocols are optimization of transmission time, minimization of collisions and avoidance of crosstalks. Categories of Multiple Access Protocols Multiple access protocols can be broadly classified into three categories - random access protocols, controlled access protocols and channelization protocols. ...
Read MoreWhat are noiseless and noisy channels?
Data link layer protocols are divided into two categories based on whether the transmission channel is noiseless or noisy. The data link layer protocol is diagrammatically represented below − Noiseless Channels There are two noiseless channels which are as follows − Simplex channel Stop & wait channel Let us consider an ideal channel where no frames are lost, duplicated, or corrupted. We introduce two protocols for this type of channel. These two protocols are as follows − Protocol that does not use flow control. Protocol that uses the ...
Read MoreMultifactor Authentication
Multi-factor Authentication: What is it? Users must submit additional information in addition to their passwords when using the multi-factor authentication (MFA) method of account login. In addition to the username and password, users could be required to input a code provided to their email address, respond to a confidential question, or scan their finger. In the case that an account's credentials get compromised, an additional method of authentication can aid in preventing unauthorized account access. Why do you Need Multi-factor Authentication? Because organizations and people store confidential data online, digital security is essential in the modern era. Everyone uses online ...
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