agenda client/server model ip addresses urls domain names read zeid: page 3-20
Post on 28-Dec-2015
224 Views
Preview:
TRANSCRIPT
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:
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
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
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
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
top related