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IT 210: Web-based IT

IT 210: Web-based IT. Fall 2012 IP Address Details & HTTP Protocol. IP Address Details. Refresher…. What function do IP Addresses serve?. IP Addresses. Composed of 2 parts: network ID (prefix assigned by ISPs) and host ID (suffix assigned by local sysadmin )

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IT 210: Web-based IT

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  1. IT 210:Web-based IT Fall 2012 IP Address Details & HTTP Protocol

  2. IP Address Details

  3. Refresher… • What function do IP Addresses serve?

  4. IP Addresses • Composed of 2 parts: network ID (prefix assigned by ISPs) and host ID (suffix assigned by local sysadmin) • IPv4 addresses consist of 4 octets • How much of the IP address is used as a network ID? 216.24.63.132

  5. Assigning IP Addresses

  6. Classful IP Address Assignment

  7. IP address classes (32 bits = v4)

  8. Many exceptions • 127.0.0.0 -127.255.255.255 = loopback • 127.0.0.1 = “home” or localhost • Private addresses (see table)

  9. Script Kiddies

  10. CIDR (Classless Inter-Domain Routing) • The “prefix” (ironically shown after the IP address) indicates how many bits in the Network ID. E.g., 192.168.0.0/16 CIDR & # ofHosts /13 524,288 /14 262,144 /15 131,072 /16 65,536 /17 32,768 /18 16,384 /19 8,192 /20 4,096 /21 2,048 /22 1,024 /23 512 /24 256 /25 128 /26 64 /27 32

  11. Dynamic vs Static IP Addresses • Static vs Dynamic

  12. IP4 vs IP6 • In Jan 2011 we ran out of IPv4 addresses. • IP4: • 32-bit address • 4.2 billion addresses available (232) • 10.8.240.2 • IP6: • 128-bit address • 3.4 x 1038 addresses available (2128) • 2001:0f68:0000:0000:0000:0000:1986:69af which condenses to 2001:f68::1986:69af

  13. Aside: What is an RFC? • RFC • “Request for Comment” • Modern RFCs are NOT requesting comments (Draft docs are used for that) • Standards, informational, and other stuff • Published by IETF • IETF = Internet Engineering Task Force

  14. References • RFC 1518 - An Architecture for IP Address Allocation with CIDR • RFC 1519 - Classless Inter-Domain Routing (CIDR): an Address Assignment and Aggregation Strategy • RFC 2373 - IP Version 6 Addressing Architecture

  15. Questions… • True or False: The classless inter-domain routing (CIDR) system helps assure that fewer IP addresses are “wasted”. • True or False: When I switch networks my IP address will also need to change. • How many unique IP addresses are there in IP4 and IP6?

  16. Open up command-line… • Type in ipconfig • Now try ipconfig /all • Compare the IP address to what you find here: http://www.whatismyip.com • Try this again at home. Will it be different?

  17. HTTP

  18. See online tutorial • http://www3.ntu.edu.sg/home/ehchua/programming/webprogramming/HTTP_Basics.html

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