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 ebreimer@siena.edu

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)

edu is the top level domain siena is essentially Siena College’s network cs is the CS Dept Network (sub-set of Siena)

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 some are widely available via URLs and Web-

based 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 serverCS Server: Compaq Intel Pentium III running an Apache web server for RedHat Linux 7.1 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 ServersRough map of the world as seen from our web serverYour web is only as fast as your slowest network bottleneck.

Ken Swarner’s office

www (ares)

Roger Bacon

Siena College

Web Servers

Web servers do NOT have to be dedicated There can be other software Other processes running Other purposes

Web servers are often Application servers Database servers Domain name servers Personal computers

Web Servers

Powerful servers 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 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. First, you need to get software

2. Second, you need a pretty good internet connection

3. Third, you need to register a domain name

4. 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) 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 Somewhat easier to setup than Apache

Internet connections

Dial-up $10-30/month

DSL $30-40/month

Cable $40-50/month

RRHome Office

MONTHLY FEE $79.95 $199.95 $249.95 $399.95 $399.95

DOWNSTREAM 2 Mbps 2 Mbps 3 Mbps 4 Mbps 1.5 Mbps

UPSTREAM 384 KBPS 768 Kbps 768 Kbps 1 Mbps 1.5 Mbps

RR PremierRR Pro RR Corporate RR Enterprise

Internet connections

T1 $250 to $1000/month 1-3 Mbps

T3 $3000 to $15,000/month 3-45 Mbps

Internet connections

OC-3 $20,000 to $50,000/month 150+ Mbps

OC-12 Over $500,000 year 600+ Mbps

OC-48 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

Siena now has RoadRunner Premier (perhaps two separate

connections) about 6 Mbps (just a guess

Internet Connections

RPI (3 years ago) Equivalent of 2 dedicated T-3’s 50+ Mbps 10-times Siena’s bandwidth.

Now, they may have an OC-3 150+Mbps 30-times Siena’s bandwidth

Domain Names

Once managed by the InterNIC Internet Network Information Center

Non-profit organization of professional Public interest in mind Still manages .org in North America

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.

APNIC (Asia Pacific Network Information Centre) - Asia/Pacific Region

ARIN (American Registry for Internet Numbers) - North America and Sub-Sahara Africa

LACNIC (Latin American and Caribbean IP address Regional Registry) - Latin America and some Caribbean Islands

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 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 ServerThis will have a cascading effect and eventually your domain can be reached.

My computer

IP Address:204.168.0.207

ISP

Domain Name Table…www.breimer.org 204.168.0.207…

DNSAuthority

Multi-tiered

Domain Names & Hosting

Companies that register your domain name are often ISP’s and

Will set you up with: 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 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 Your own server Your own support personal Your own infrastructure

Other hosting options

Free services Angelfire Geocities

Cheap services Roadrunner AOL

Piggy-backing College Company