Transcript Power Point Slides

Agenda
Client/Server Model
IP Addresses
URLs
Domain Names
READ Zeid: page 3-20
URLs
Uniform Resource Locator
Human-readable WWW Address
Examples:
http://www.cs.siena.edu
 ftp://ftp.cs.rpi.edu
 [email protected]

Includes email addresses and newsgroups
URLs
Example: http://www.cs.siena.edu
http is the protocol
 www is the host name (server name)
 cs.siena.edu is the domain (network address)
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edu is the top level domain
 siena is essentially Siena College’s network
 cs is the CS Dept Network (sub-set of Siena)
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WhoIs Search
Lets do a Whois Search on some popular
domains
http://whois.educause.net/
siena.edu
harvard.edu
IP Addresses
Numeric Internet Address
Part of the TCP/IP Protocol
URLs are translated into IP Addresses by
DNS Servers
DNS  Domain Name System
IP Addresses
Example: 64.236.24.4
4 numbers separated by decimal points
64 is the top level network
4 is a specific computer (host or server)
Lets do an nslookup on an IP Address
Client/Server
The WWW is huge client/server system
with millions of web servers (called hosts)
 and soon to be billions of clients

Web Servers are obviously the servers
Web Browsers are the client applications
Other Servers on the Internet
Companies also have Database servers that
are connected to the Internet
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some are widely available via URLs and Webbased Interfaces
Wanna see my favorite one?
Protocols to remember
HTTP
HTTPS
mailto
NNTP (Network News Transfer Protocol)
Telnet, SSH, Secure Shell
File:
Intranets vs. Extranets
What is the difference?
What does Siena have?
What does the CS Dept. have?
Web Browsers
Internet Explorer
Netscape
Mozilla
Opera
Why does it matter?
Web Browsers
Things that really matter
cache
3rd party toolbars
Plug-ins
History lists, privacy, security
Things everyone should know.
Web Servers
Any computer can be a web server
CS Server: Compaq Intel Pentium III running an
Apache web server for RedHat Linux 7.1
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Adequate for about 50-60 http requests per minute
Actually get about 250 request per day
Why is the CS website so slow?
It depends on where you are?
Web Servers
Rough map of the world as seen from our web
server
Your web is only as fast as your slowest network
bottleneck.
Siena College
Roger Bacon
Ken Swarner’s
office
www
(ares)
Web Servers
Web servers do NOT have to be dedicated
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There can be other software
Other processes running
Other purposes
Web servers are often
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Application servers
Database servers
Domain name servers
Personal computers
Web Servers
Powerful servers
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Multiple processors for handling simultaneous requests
Lots of memory (RAM) so files don’t have to be
retrieved from slow hard drives
RAM is perhaps the most important investment
Who has powerful servers
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Yahoo, Google, Amazon, Ebay, Travelocity
Major networks: CNN, ABC, NBC, CBS, etc. (ESPN)
Microsoft, IBM, & ??? (Dell???)
Web Servers
How can I set up my own web server.
1.
2.
3.
4.
First, you need to get software
Second, you need a pretty good internet connection
Third, you need to register a domain name
Finally, you need to actually make some webpages
How much does this all cost?
How hard is it?
Web server software
Apache (its free and its very good)
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UNIX and Windows versions
Problems:
Not super easy to setup or configure
If you are not already a nerd, you’ll probably need a
lot of time.
Microsoft makes several different servers
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Somewhat easier to setup than Apache
Internet connections
Dial-up $10-30/month
DSL $30-40/month
Cable $40-50/month
MONTHLY FEE
DOWNSTREAM
UPSTREAM
RR
Hom e
Office
RR Pro RR Corporate RR Enterprise RR Prem ier
$79.95 $199.95
$249.95
$399.95
$399.95
2 Mbps
2 Mbps
3 Mbps
4 Mbps
1.5 Mbps
384 KBPS 768 Kbps
768 Kbps
1 Mbps
1.5 Mbps
Internet connections
T1
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$250 to $1000/month
1-3 Mbps
T3
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$3000 to $15,000/month
3-45 Mbps
Internet connections
OC-3
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$20,000 to $50,000/month
150+ Mbps
OC-12
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Over $500,000 year
600+ Mbps
OC-48
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Good luck finding one
used internally by companies like Sprint who sell the
above connections
2400+ Mbps
Internet Connections
Siena used to have
3 dedicated T-1 lines (bundled?)
 about 3 Mbps
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Siena now has
RoadRunner Premier (perhaps two separate
connections)
 about 6 Mbps (just a guess
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Internet Connections
RPI (3 years ago)
Equivalent of 2 dedicated T-3’s
 50+ Mbps
 10-times Siena’s bandwidth.
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Now, they may have an OC-3
150+Mbps
 30-times Siena’s bandwidth
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Domain Names
Once managed by the InterNIC
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Internet Network Information Center
Non-profit organization of professional
 Public interest in mind
 Still manages .org in North America
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Who manages domains now?
Domain Names
The Internet Assigned Numbers Authority (IANA) is the overall
authority for the IP Addresses, the Domain Names, and many
other parameters, used in the Internet.
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APNIC (Asia Pacific Network Information Centre) - Asia/Pacific
Region
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ARIN (American Registry for Internet Numbers) - North America
and Sub-Sahara Africa
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LACNIC (Latin American and Caribbean IP address Regional
Registry) - Latin America and some Caribbean Islands
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RIPE NCC (Réseaux IP Européens) - Europe, the Middle East,
Central Asia, and African countries located north of the equator
Domain Names
Many companies act as a 3rd (and even 4th)
party and will register your domain name
with the proper authorities.
The InterNIC itself acts as a 3rd party in
registering many domain names.
Registering a domain just reserves the
name.
Spoofing
Ultimately, Domain name servers determine
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Which domain names are associated with which
hosts.
Remind me to tell you a story.
Domain Names
Domain Names
To get the Internet to recognize your domain you
have to get your ISP to add your domain to its
Domain Name Server
This will have a cascading effect and eventually
your domain can be reached.
Domain Name Table
…
www.breimer.org  204.168.0.207
IP Address:
204.168.0.207
ISP
…
My computer
DNS
Authority
Multi-tiered
Domain Names & Hosting
Companies that register your domain name are
often ISP’s and
Will set you up with:
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A domain name
A dedicated IP address
And, they make sure you get added to the right tables
Associates your IP address with your domain.
On-site vs. Off-site
Most hosting companies have their own servers
and will provide off-site hosting
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Off-site means they host your stuff on their servers
You don’t have your own servers on-site
Most ISP can set you up on-site if you have
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Your own server
Your own support personal
Your own infrastructure
Other hosting options
Free services
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Angelfire
Geocities
Cheap services
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Roadrunner
AOL
Piggy-backing
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College
Company