In these post I will highlight the most important point in every section of chapter six
6.1 What Is a Computer Network?
A computer network is a system that connects computers and other devices via communications media so that data and information can be transmitted among them.
*Size of Computer Networks:-
- Home computer network
- National computer network
- Global computer network
*Local Area Networks:-
A local area network connects two or more devices in a limited geographical region so that every device on the network can communicate with every other device.
6.2 Network Fundamentals
*Analog and Digital Signals:-
- Communications Media and Channels:
- Twisted-pair wire
- Coaxial cable
- Fiber optics
- Transmission Technologies:
- Digital Subscriber Line: a high-speed, digital data transmission technology using existing analog telephone lines.
- Asynchronous Transfer Mode: data transmission technology that uses packet switching and allows for almost unlimited bandwidth on demand.
- Synchronous Optical Network: an interface standard for transporting digital signals over fiber optic lines that allows users to integrate transmissions from multiple vendors.
- T-Carrier System: digital transmission system that defines circuits that operate at different rates, all of which are multiples of the basic 64 Kbps user to transport a single voice call.
*Network Protocols:
A protocol is the set of rules and procedures governing transmission across a network.
Ethernet is a common LAN protocol.
Transmission Control Protocol/Internet Protocol (TCP/IP) is a file transfer protocol that can send large files of information across sometimes unreliable networks with assurance that the data will arrive uncorrupted
Types of Network Processing:
- Client/server computing
- Peer-to-peer processing
6.3 The Internet and the World Wide Web
*Addresses on the Internet:
Domain names consist of multiple parts, separated by dots, which are red from right to left.
Top-level domain: the rightmost part of an Internet name; common top-level domains are .com, .edu, .gov
Name of the company: the next section of the Internet name
Name of the specific computer: the next section of the Internet name
*The World Wide Web:
World Wide Web: A system of universally accepted standards for storing, retrieving, formatting, and displaying information via a client/server architecture.
Home page: a text and graphical screen display that usually welcomes the user and explains the organization that has established the page.
Uniform resource locator: the set of letters that points to the address of a specific resource on the Web.
6.4 Network Applications
*Discovery
Discovery allows users to browse and search data sources, in all topic areas, on the Web.
Search engines are computer programs that search for specific information by key words and report the results.
Metasearch engines search several engines at once and integrate the findings of the various search engines to answer queries posted by users.
The largest search engines are:
- Yahoo
- Bing
- Baidu
*Portals
Portal is a Web-based, personalized gateway to information and knowledge that provides relevant information from different IT systems and the Internet using advanced search and indexing techniques.
Commercial (public) portals offer content for diverse communities and are most popular portals on the Internet.
Affinity portals support communities such as a hobby group or a political party.
Mobile portals are accessible from mobile devices.
Corporate portals offer a personalized single point of access through Web browser Industry wide portals for entire industries.
*Communication
Electronic mail (e-mail) is the largest-volume application running on the Internet.
Web-based call centers (customer call center) are services that provide effective personalize customer contact as an important part of Web-based customer support.
Electronic chat room is a virtual meeting place where groups of regulars come to “gab”.
*Voice Communication
Internet telephony (VoIP) (voice-over IP) digitizes your analog voice signals, sections them into packets, and sends them over the Internet.
Two examples of Internet telephony (VoIP):
- Skype
- Vonage
*Collaboration
Collaboration refers to efforts of two or more entities (individuals, teams, groups, or organizations) who work together to accomplish certain tasks.
Work group refers specifically to two or more individuals who act together to perform some task.
Virtual group (team) is when group members are in different locations.
Virtual collaboration is the use of digital technologies that enable organizations or individuals to collaboratively plan, design, develop, manage and research products, services and innovative applications.
Workflow technologies facilitate the movement of information as it flows through the sequence of steps that make up an organization’s work procedures. Includes workflow management and workflow systems.
Groupware refers to software products that support groups of people who share a common task or goal and who collaborate to accomplish it.
Teleconferencing is the use of electronic communication that allows two or more people at different locations to hold a simultaneous conference.
Videoconference is when participants in one location can see participants at other locations and share data, voice, pictures, graphics and animation by electronic means.
Web conferencing is videoconferencing conducted over the Internet.
Real-time collaboration tools support synchronous communication of graphical and text-based information i.e. computer-based whiteboards.
*Telecommuting
Telecommuting Benefits:
- For Employees:
- Reduced stress, improved family life
- Employment opportunities for single parents and persons with disabilities
- For Employers:
- Increased productivity
- Ability to retain skilled employees
Telecommuting Disadvantages:
- For Employees:
- Feelings of isolation
- No workplace visibility
- Potential for slower promotions
- For Employers:
- Difficulties in supervising work
- Potential information security problems
- Additional training costs
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