DNS: Domain Name System Mark Ciocco Chris Janik Networks Class Presentation Tuesday April 18, 2000 To insert your company logo on this slide From the Insert Menu Select “Picture” Locate your logo file Click OK To resize the logo Click anywhere inside the logo. The boxes that appear outside the logo are known as “resize handles.” Use these to resize the object. If you hold down the shift key before using the resize handles, you will maintain the proportions of the object you wish to resize.

Presentation 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 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

What is it? Global network of servers that translate host names such as into numerical IP addresses like 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 101 DNS 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 Internet Number of hosts registered with the DNS January ,398,092 January ,670,000 January ,352,000 January 19931,313,000

Naming History 102 DNS –Domain Name Space

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 EXAMPLE DNS –Domain Name Space

Movin’ 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

Root 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 2

DNS 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) –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? –NSI’s monopoly ended –April 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 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 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

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

More 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 END Comments or questions? Thank you!