This document discusses web servers and their role in delivering web pages on the internet. It defines a web server as a computer that delivers content via the Hypertext Transfer Protocol (HTTP) and notes they include hardware, operating systems, server software, and TCP/IP protocols. The document also mentions some of the largest web servers in the world like Google, Amazon, and Facebook, with Google estimated to have over 900,000 servers. Finally, it reviews common web server technologies, secure servers using SSL, email services, and storage solutions on the internet.

1. Introduction
Master Class 5
Internet infrastructures & Technologies :
Internet Systems & applications II
Josep Bardallo 2012

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Services used in Internet (application layer)

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Web Server. Definition
 Webserver: A computer that deliver content in Internet.
 The primary function of a web server is to deliver web pages on the
request to clients using the Hypertext Transfer Protocol (HTTP).

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Web Servers. Elements
 The Web server includes the hardware, operating system, Web
server software, TCP/IP protocols and site content (Web pages,
images and other files).
 A user agent (web browser), initiates communication by making a
request for a specific resource using HTTP and the server responds
with the content of that resource or an error message if unable to do
so.
 Web servers are not only on Internet. HTTP server software is
commonly built into hardware to provide a control panel for
configuring the device from any Web browser, or for Intranets.

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Web Servers in the world by domain (Oct. 2012)

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Web Servers Architecture: 3 Tier Layer

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Typical architectures: Standard services in a company

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Typical architectures: Complex Web environment.
Sample 1 (Real Case)

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Typical architectures: Complex Web environment.
Sample 2 (Real Case). Car selling

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Typical architectures: Complex Web environment.
Sample 3 (Real Case). City Council

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Typical architectures: Complex Web environment.
Sample 3 (Real Case). City Council

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Typical architectures: Complex Web environment.
Sample 3 (Real Case). City Council

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Web Servers. Top 500 sites
http://www.alexa.com/topsites

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Number of servers of Top 100 (estimated and
growing)
 Google: estimated more than 900.000 servers
 Amazon: 500.000+ (322.000+ Virginia, 1.600 in Sao Paulo in 25
racks)
 Microsoft 300.000+ servers
 Facebook: 180.000+
 QVH: 120.000+ servers
 Softlayer, Rackspace, Akamai, Yahoo: 100.000+ servers
 Intel, 1&1, Ebay, GoDaddy: 70.000+ servers
 Verizon, Time Warner: 30.000+ servers

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Web Servers Technology

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Web Servers Technology

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User Agent: Operating Systems in Internet

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User Agent: Web Browsers in Internet

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User Agent: Web Browsers in Internet. Trends

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User Agent: Web Browsers in Internet. By Country

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Secure Servers (SSL)
 Secure Sockets layer (SSL) is a form of protocol, used by e-
commerce sites, on-line banking and financial services to secure
communications by encrypting the data transmitted between two
points over Internet
 When the user enters a site with SSL certificate, they public key of
the site certificate is received by the browser and used to encrypt
the submitted information. The data can only be decrypted with the
key issued to the certificated site, assuring it will be readable only
by the internet intended recipient.

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Email
 Electronic mail, or e-mail, is a method of exchanging digital
messages from an author to one or more recipients

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Email: Elements
 Email Client, SMTP Server (MTA), POP Server

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Email: Workflow

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MTA Vendors

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Email: Some numbers

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Email: Some numbers

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Email: SPAM

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Internet Video & Images

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Storage in Internet

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Bibliography
 http://w3techs.com/technologies/cross/web_server/ranking
 http://gigaom.com/cleantech/facebooks-number-of-servers-soar-to-an-estimated-180k/
 http://news.netcraft.com/archives/2012/07/03/july-2012-web-server-survey.html
 http://www.radicati.com/wp/wp-content/uploads/2011/05/Email-Statistics-Report-2011-2015-Executive-
Summary.pdf
 http://www.clickz.com/type/news/category/stats
 http://www.symantec.com/theme.jsp?themeid=state_of_spam
 http://www.mailradar.com/
 http://www.w3counter.com/globalstats.php?year=2012&month=9
 http://marketshare.hitslink.com/
 http://www.wired.com/wiredenterprise/2012/03/amazon-ec2/