DNS:DNS:Domain Name SystemDomain Name System

Mark Ciocco

Chris Janik

Networks Class Presentation

Tuesday April 18, 2000

Presentation OutlinePresentation Outline

• What it is and how it works

• How the Internet worked before DNS

• DNS through the years

• How you can register for your own domain name

Foreign LanguagesForeign Languages

• Humans:– Words are easy to remember– Numbers are confusing

• Machines:– Numbers are easy to work with– What are words?

• Would amazon.com be what it is today if it were 208.202.218.15

What is it?What is it?

• Global network of servers that translate host names such as www.villanova.edu into numerical IP addresses like 153.104.1.200

• An internet protocol, distributed database and software existing on many different name servers around the world allowing for almost unlimited growth of the Internet

DNS History 101DNS History 101

• Pre - DNS– A single file (host table) containing a table

of all the host names that was distributed via FTP to all domain name servers

– Updated manually by SRI-NIC a couple times a week

• worked fine but not efficient or practical• Paul Mockapetris invents DNS in 1984

Explosion of the InternetExplosion of the Internet

Number of hosts registered with the DNS

January 2000 72,398,092

January 1998 29,670,000

January 1996 14,352,000

January 1993 1,313,000

Naming History 102Naming History 102

• DNS– Domain Name Space

How Does It Work?How Does It Work?

1.) DNS Server– a computer that runs DNS software– mostly UNIX machines so most popular program is BIND

(can find software for Mac and PC)– authoritative vs caching

2.) DNS Software Components– The Name Server: responds to requests by supplying

name to address conversion– The Resolver: in the case of Name Server failure the

Resolver looks for the information on another name server

DNS LOOKUP EXAMPLEDNS LOOKUP EXAMPLE

• DNS– Domain Name Space

Movin’ On Down The LineMovin’ On Down The Line

•Root Servers•DNS server asks for master server for .edu

•Master Servers•DNS server asks for domain server for villanova.edu

•Domain Servers•DNS server asks for server that holds villanova.edu

•Individual Servers•Supplies DNS server with IP address for the machine called www.villanova.edu

Root Server SystemRoot Server System

• Because of its basis as a singly rooted hierarchical namespace, DNS is one of the single points of failure within the Internet

• More specifically, the root of this system

• It is held in 13 geographically distributed root name servers operated by 9 independent organizations

Root Server System 2Root Server System 2

Name Organization City, State/Province Country

B Information Sciences Institute, Marina Del Rey, CA USAA Network Solutions, Inc Herndon, VA USA

D University of Maryland College Park, MD USAC PSINet Herndon, VA USA

F Internet Software Consortium Palo Alto, CA USAE National Aeronautics and Space Mountain View, CA USA

H Army Research Laboratory Aberdeen, MD USAG Defense Information Systems Vienna, VA USA

J (TBD) Herndon, VA USAI NORDUNet Stockholm Sweden

USAK RIPE-NCC London UK

Root Name Server Operators and Locations

M WIDE Tokyo JapanL (TBD) Marina Del Rey, CA

DNS ControlDNS Control

– Was controlled by Network Solutions (NSI) and Internet Assigned Numbers Authority (IANA).

– IANA replaced by a non governmental organization called ICANN.

DNS Control (con’t)DNS Control (con’t)

– Internet Corporation for Assigned Names as Numbers (ICANN)

• Comprised of a board of 19 people picked by the US Department of Commerce.

• Non profit organization that oversees the administrative needs of the internet in a fair and impartial manner.

• They will distribute the remaining IP numbers to regional registries who will pass them on to ISPs. The ISP will then assign the addresses to their individual customers.

New Registrars?New Registrars?

– NSI’s monopoly ended– April 1999 - Test phase in which 5

additional registrars were permitted to use the shared registration system.

– August 1999 • Test phase is extended• now allows 52 additional registrars• All additional registrars use NSI’s registration

system (for a fee!)

New Registration SystemNew Registration System

– December 1999• Phasing out NSI’s registration system• New Shared Registration System (SRS)• SRS has some glitches, but it is a fair system

– NSI• Still the dominant registration service• Makes them tough to compete with

How do I get a domain name How do I get a domain name for myself?for myself?

– Register with an accredited registrar to get a .com, .net, or .org top level domain

• Registrars include: NSI, Register.com, and AOL.

• $70 initial investment for 2 years• $35 for each additional year

– Most ISPs offer domain name registration services

AlternativesAlternatives

• You can bypass the registrars and get a country code top level domain such as .us, .uk, .md, or .tv.

More AlternativesMore Alternatives

• AlterNIC– Another alternative that offers exotic top

level domains such as .ltd, .inc, .games and the ever popular .xxx

– Not really a viable alternative because it requires net users to set up their computers to use AlterNICs DNS servers.

THE ENDTHE END

• Comments or questions?

• Thank you!