CCNA-1. Chapter1. Living in a network centric world

Internet provides new forms of communications:

• Instant Messaging (Developed from Internet Relay Chat (IRC) services. Features: file transfer, voice, video communication, received immediately.
• Weblogs (blogs) (Communicate thoughts to a global audience without technical knowledge of web design)
• Wikis Wikis (Groups of people can edit and view together. businesses use wikis as their internal collaboration tool.
• Podcasting

Networks must meet four basic characteristics:

• Fault tolerance,
• Scalability,
• Quality of service (to overcome congestions)
• Security (avoid unauthorized disclosure,theft, modification, Denial of Service of information)

Types of networks architecture

• Circuit Switched Connection-oriented Networks(message consistency,can be charged by time,no fault tolerance ,hard scalability)
• Packet-switched Connectionless Networks(fault tolerance, scalability)

Data network consists of:

• Devices
• Medium
• The digital messages
• Rules (protocols)

Components of network architecture:

• Programmed services and protocols that move messages across the netwok
• Technologies that support network communications

Network – interconnected devices capable of carrying many different types of communications.
Intranets - private networks in use by just one company, enable businesses to communicate and perform transactions among global employee and branch locations (used by employees)  
Extranets(extended internetworks) - part of intranet that provide suppliers, vendors, and customers limited access to corporate data to check order status, inventory, and parts lists. (used by customers)
Internetwork - interconnection of 2 or more networks  
Internet - most well-known publicly accessible internetwork belonging to Internet Service Providers (ISPs), uses IP protocol.