IT 210: Web-based IT
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Transcript of IT 210: Web-based IT
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IT 210:Web-based IT
Fall 2012IP Address Details & HTTP
Protocol
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IP Address Details
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Refresher…
What function do IP Addresses serve?
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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
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Assigning IP Addresses
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Classful IP Address Assignment
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IP address classes (32 bits = v4)
Class Leftmost bits
Start address
Finish address
Net bits Host bits
A 0xxx 0.0.0.0 127.255.255.255
7 24 (16M)
B 10xx 128.0.0.0 191.255.255.255
14 16 (65K)
C 110x 192.0.0.0 223.255.255.255
21 8 (256)
D 1110 224.0.0.0 239.255.255.255
multicast
E 1111 240.0.0.0 255.255.255.255
experimental
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Many exceptions 127.0.0.0 -127.255.255.255 = loopback
127.0.0.1 = “home” or localhost Private addresses (see table)
Class Private start address Private end address
A 10.0.0.0 10.255.255.255
B 172.16.0.0 172.31.255.255
C 192.168.0.0 192.168.255.255
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Script Kiddies
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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 & # of Hosts/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
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Dynamic vs Static IP Addresses Static vs Dynamic
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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
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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
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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
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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?
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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?
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HTTP
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See online tutorial http://www3.ntu.edu.sg/home/ehchua/
programming/webprogramming/HTTP_Basics.html