![Dotted Decimal Notation
• IP addresses are written in a so-called dotted
decimal notation
• Each byte is identified by a decimal number in the
range [0..255]
• Example:
10000000 10001111 10001001 10010000
1st Byte
= 128
2nd Byte
= 143
3rd Byte
= 137
4th Byte
= 144
128.143.137.144](https://image.slidesharecdn.com/internetnew-141030140208-conversion-gate01/85/Internet-new-13-320.jpg)
Internet new
- 1. THE INTERNET
- 2. The Internet • The Internet: An internet that spans the world – Original goal was to develop a means of connecting networks that would not be disrupted by local disasters.
- 3. The Internet • An information system • Communication tool • A large network of computer systems world wide • can be explored by using a Web Browser • Services available through the Internet: • Email (Discussion groups , Chat Rooms, etc.) • Information search (including research) • Education (Online courses; virtual colleges) • Entertainment, News, and more…...
- 4. Internet Architecture • Internet Service Provider (ISP) • Access ISP: Provides connectivity to the Internet – Traditional telephone (dial up connection) – Cable connections – Wireless
- 6. A network protocol Is the set of very detailed rules, sequences, message formats, and procedures that computer systems use and understand when exchanging data with each other.
- 7. Examples of Protocols – Transmission Control Protocol (TCP) – User Datagram Protocol(UDP) – File Transfer Protocol (FTP) – Hypertext Transfer Protocol (HTTP) – Simple Mail Transfer Protocol (SMTP)
- 8. Transmission Control Protocol (TCP/IP) • It is connection oriented. • It establish connection before data transfer • It divide the whole message in small parts known as packets • It sends packets in order and it also receive in order in destination
- 9. User Datagram Protocol(UDP) • It is not connection oriented. • It does not establish connection before data transfer • It divide the whole message in small parts known as packets. • It sends packets to the available path on that particular movement. • The packets are not received in order and it required a addition mechanism for ordering the packets on destination.
- 10. File transfer protocol • Is a network protocol used for transfer data from one computer to another through a network such as Internet (is commonly used for copying files to and from other computers) • FTP is a two-way system - it can be used to copy or move files from a server to a client computer as well as upload or transfer files from a client to a server • FTP systems generally encode and transmit their data in binary sets which allow for faster data transfer
- 11. What is an IP Address? • An IP address is a unique global address for a network interface – An IP address: - is a 32 bit long identifier - encodes a network number (network prefix) and a host number.
- 12. Network prefix and host number • The network prefix identifies a network and the host number identifies a specific host (actually, interface on the network). network prefix host number
- 13. Dotted Decimal Notation • IP addresses are written in a so-called dotted decimal notation • Each byte is identified by a decimal number in the range [0..255] • Example: 10000000 10001111 10001001 10010000 1st Byte = 128 2nd Byte = 143 3rd Byte = 137 4th Byte = 144 128.143.137.144
- 14. IP Addresses (continued) • When IP addresses were originally created, they were called classful addresses – That is, each IP address fell into particular class – A particular class address has a unique network address size and a unique host address size – There are basically five types of IP addresses: Classes A, B, C, D and E 14
- 15. IP Addresses (continued) 15
- 16. IP Addresses (continued) • When you examine the first decimal value in the dotted decimal notation: – All Class A addresses are in the range 0 - 127 – All Class B addresses are in the range 128 - 191 – All Class C addresses are in the range 192 – 223 – All Class D addresses are in the range 224 – 239 – All Class E addresses are in the range 240 - 255 16
- 17. Name servers
- 18. DNS • IP addresses are difficult to remember – JohnDoe@140.203.8.22 would be difficult to remember – If JohnDoe’s mail server moves to another machine, then his e-mail address would not be valid anymore – Something like JohnDoe@wuzwuz.ucg.ie would be appropriate • Need some mechanisms to translate wuzwuz.ucg.ie to the IP address – To solve this problem DNS was invented • It is a hierarchical, domain-based naming scheme and a distributed database system for implementing naming scheme. • Usage: – Map name onto an IP address, an application program calls an library procedure, called resolver. – The resolver sends packet to a local DNS server which looks up the name and returns the IP address to the resolver – The resolver returns the IP address to the application, which can establish an TCP/IP connection with the destination (or send packets)
- 19. URL – Uniform Resource Locator
- 20. URL – Uniform Resource Locator
- 21. Traditional Internet Applications • Electronic Mail (email) – Domain mail server collects incoming mail and transmits outgoing mail – Mail server delivers collected incoming mail to clients via POP3 or IMAP • File Transfer Protocol (FTP) • WWW (World Wide Web)
- 22. World Wide Web (WWW) – a vast collection of information that’s connected like a web – accessible through the Internet using connections called hyperlinks – view the WWW resources through a program called a Web Browser, such as: • Netscape Navigator • Internet Explorer – Navigate through the WWW by pointing to and clicking on hyperlinks (underlined or boldfaced words, phrases, icons, or images) – Also called Cyberspace or the Information Superhighway
- 23. Architectural Overview • Browser displays a page on the client machine – Click on a link, the browser sends a message to the abcd.com web server asking it for the page – When page arrives, it is displayed; if it contains a hyperlink on a page on xyz.com, that is clicked, then the browser will send a message to xyz.com server and the process continues
- 24. HTML – HyperText Markup Language • (a) HTML source code – Markup language containing explicit commands for formatting • (b) Formatted page