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Switching: A switch is a mechanism that allows us to interconnect links to form a larger network. A switch is a multi-input, multi-output device that transfers packets from an input to one or more outputs. A Switch's primary job is to receive incoming packets on one of its links and to transmit them on some other link. This function is sometimes referred as switching or forwarding. Types of Switching Data-gram or connection less approach. Virtual circuit or connection oriented approach. Source Routing. All networks need to have a way to identify the end nodes. such identifiers are usually called addresses. Data-gram: We include in every packet enough information to enable any switch to decide how to get it to its destination. That is every packet contains the complete destination address. To decide how to forward a packet, a switch consults a forwarding table sometimes called routing table. Characteristics of Data-gram networks: A host can send a

Relational DBMS: The term relational database was originally defined by Edgar Cod at IBM Research Center in 1970. Relational database as implemented in relation database management system have become a predominant choice for the storage of information in new databases used for financial records manufacturing and logistical information personnel data and much more. In the relational database the user only needs to understand the logical structure of data not how it is physically stored. In this database data is represented in simple two-dimensional tables which consists of rows and columns. A relational database is simply a collection of tables. Relational database theory uses a set of mathematical terms which are roughly equivalent to SQL database terminology. Relational Database Basic Concepts: Relations Or Tables: A relation is defined as a set of tuples that have the same attributes. A tuple usually represents an object and information about that objects ar

Underlying Structure of the database is called as data model. It is a collection of conceptual tools for describing data, data relationships, data semantics, and consistency constraints. Different types of data models are Entity relationship model, Relational model, Hierarchical model, Network model, Object oriental model and Object relational model. Entity Relationship model: The Entity relationship model consists of a collection of basic objects called entities and of relationships among these entities. Entity: An entity is a thing or object in the real world that is distinguishable from other objects. For example each person is an entity and bank accounts is an entity. Entities are described in a database by a set of attributes. For example the attributes of account entity are account entity are account_no and balance. Relationship: A relationship is an association among several entities. For example a depositor relationship associates a customer with each accou

The System test is a series of tests conducted to fully the computer based system. Various types of system tests are Recovery Testing Security Testing Stress Testing Performance Testing The main focus of such testing is to test System functions and performance, System reliability and recovery test, System installation, stress test, System user operations, Hardware and Software integration and collaboration, Integration of external software and the system.   Recovery Testing: Recovery Testing is intended to check the system's ability to recover from failures. In this type of testing the software is forced to fail and then it is verified whether the system recovers properly or not. For automated Recovery then re-initialization, checkpoint mechanisms, data recovery and restart are verified. Security Testing: Security testing verifies that system protection mechanism prevent improper penetration or data alteration. It also verifies that protection

A group of dependent components are tested together to ensure their quantity of their integration unit. The objective is to take unit tested components and build a program structure that has been dictated by software design. The focus of integration testing is to uncover errors in design and construction of software architecture, Integrated functions or operations at subsystem level, Interfaces and interactions between them and resource integration or environment integration. The integration testing can be carried out using two approaches. They are non-incremental integration and incremental integration. The non incremental integration is given by the big bang approach. All component are combined in advance. The entire program is tested as a whole. A set of error is tested as a whole. Correction is difficult because isolation of causes is complicated by the size of the entire program. Once these errors are corrected new ones appear. This process continues infinitely A

We begin by testing in the small and move toward testing in the large. Various testing strategies for conventional software are unit testing, integration testing, validation testing, system testing. Unit testing: In this type of testing techniques are applied to detect the errors from each software component individually. Integration testing: It focuses on issues associated with verification and program construction as components begin interacting with one another. Validation testing: It provides assurance that the software validation criteria meets all functional and performance requirements.  System testing: In system testing all system elements forming the system is tested as a whole.  Unit Testing: In unit testing the individual components are tested independently to ensure the quality. The focus is to uncover the error in design and implementation. The various  tests that are conducted during the unit test are described as below. Module interfaces are

The Software design concept provides a framework for implementing the right software.Following are certain issues that are considered while designing the software. Abstraction Architecture Refinement Pattern Information hiding Functional independence  Refactoring  Design Classes Abstraction: The abstraction means an ability to cope up with the complexity. Software design occurs at different levels of abstraction. At each stage of software design process levels of abstractions should be applied to refine the software solution. At the higher level of abstraction, the solution should be started in broad terms and in the lower level more detailed description of the solution is given. While moving through different levels of abstraction the procedural abstraction and data abstraction are created. The procedural abstraction gives the named sequence of instructions in the specific function. That means the functionality of procedure is mentioned by its implementati