Section 3
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What is the Internet a world-wide collection of?
Inter-connected networks not owned or managed by any one group of people
Who can access the Internet?
Anyone
Where is all information on the World Wide Web stored?
Documents known as web pages
Is the World Wide Web and the Internet the same thing?
No
Where are websites stored?
Web Servers connected to the internet
How are web pages accessed?
Web Browser
What is the difference between the Web and the Internet?
• Web is one of the ways information is communicated over the Internet
Which is used for email and instant messaging: Internet or the Web?
Internet
What does each networked computer have that is unique?
IP address
What does an IP stand for?
Internet Protocol
What is the difference between IPv4 and IPv6?
IPv4 - Current system, Four 8-bit fields, Dotted Decimal Digits IPv6 - 128 bits, 8 groups of 16 bits, four hexa-decimal digits, separated by colons
What do you type instead of an IP address when you wish to access a site?
Domain Name or URL (Uniform Resource Locator)
What happens when a user types a URL?
• URL sent to a local DNS server, translated into IP address • If address is found, it is passed back to the browser • If not found, it is passed ‘up the chain’ to the next DNS server • If it cannot be found, an error is passed back and browser displays error message
What are the advantages of using DNS Servers to translate domain names into IP addresses?
• Humans do not have to remember or type numerical address • if address changes, DNS can update database, so users continue to use same domain name • Many distributed DNS servers so everyone can access all addresses from local DNS Server
What must a computer device have to connect to the Internet?
Network Interface Controller (NIC)
What does each NIC have?
Media Access Control Address (MAC) assigned by manufacturer
Can a device have more than one MAC address?
Yes, for example, one for wired Ethernet and one for wireless, or one for wireless and one for Bluetooth
How is a MAC address presented?
48-bit address written as twelve hex digits, make it easier for humans to work with
What is a WAN?
A Wide Area Network that connects computers over a large geographical area using third-party carriers like BT
What is the largest WAN in the world?
The Internet
What is circuit switching?
A dedicated connection set up between sender and receiver for the duration of communication (used in telephone calls)
What is packet switching?
Breaking data into packets that travel independently along different routes and are reassembled at the destination
What information is contained in a packet header?
IP address of destination, IP address of source, sequence number, total number of packets, error checking data
What is a LAN?
A Local Area Network covering a small geographical area with computers and peripherals connected on a single site