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Jul 31, 2019

Welcome to the History of Computing Podcast, where we explore the history of information technology. Because by understanding the past, we’re able to be prepared for the innovations of the future! Todays episode is on the history of the Domain Name System, or DNS for short. 

You know when you go to Imagine if you had to go to, or the IP address, instead. DNS is the service that resolves that name to that IP address. Let’s start this story back in 1966. The Beatles released Yellow Submarine. The Rolling Stones were all over the radio with Paint It Black. Indira Ghandi was elected the Prime Minister of India. US Planes were bombing Hanoi smack dab in the middle of the Vietnam War. The US and USSR agreed not to fill space with nukes. The Beach Boys had just released Good Vibrations. I certainly feel the good vibrations when I think that quietly, when no one was watching, the US created ARPANET, or the Advanced Research Projects Agency Network. 

ARPANET would evolve into the Internet as we know it today. As with many great innovations in technology, it took awhile to catch on. Late into the 1980s there were just over 300 computers on the Internet, most doing research. Sure, there were 254 to the 4th addresses that were just waiting to be used, but the idea of keeping the address of all 300 computers you wanted to talk to seemed cumbersome and it was slow to take hold. To get an address in the 70s you needed to contact Jon Postel at USC to get put on what was called the Assigned Numbers List. You could call or mail them. 

Stanford Research Institute (now called SRI) had a file they hosted called hosts.txt. This file mapped the name of one of these hosts on the network to a IP address, making a table of computer names and then IP addresses those matched with, or a table of hosts. Many computers still maintain this file. Elizabeth Feinler maintained this directory of systems. She would go on to lead and operate the Network Information Center, or NIC for short, for ARPANET and see the evolution to the Defense Data Network, or DDN for short and later the Internet. She wrote what was then called the Resource Handbook. 

By 1982, Ken Harrenstien and Vic White on Feinler’s group at Stanford created a service called Whois, defined in RFC 812, which was an online directory. You can still use the whois command on Windows, Mac and Linux computers today.

But by 1982 it was clear that the host table was getter’s slower and harder to maintain as more systems were coming online. This meant more people to do that maintenance. But Postel from USC then started reviewing proposals for maintaining this thing, a task he handed off to Paul Mockapetris. That’s when Mockapetris did something that he wasn’t asked to do and created DNS. 

Mockapetris had been working on some ideas for filesystems at the time and jumped at the chance to apply those ideas to something different. So Jon Postel and Zaw-Sing Su helped him complete his thoughts which were published by the Internet Engineering Task Force, or IETF, in in RFC 882 for the concepts and facilities and RFC 883 for the implementation and specification in November 1983. You can google those and read them today. And most of it is still used. 

Here, he introduced the concept that a NAME of a TYPE points to an address, or RDATA and lives for a specified amount of time, or TTL short for Time To Live. He also mapped IP addresses to names in the specifications, creating PTR records. All names had a TLD or Top Level Domain name of ARPANET. 

Designing a protocol isn’t the same thing as implementing a protocol. In 1984, four students from the University of California Berkeley wrote the first version of BIND, short for Berkeley Internet Name Domain, for BSD 4.3. Douglas Terry, Mark Painter, David Riggle, and Songnian Zhou using funds from a DARPA grant. In 1988 Paul Vixie from Digital Equipment Corporation then gave it a little update and maintained it until he founded the Internet Systems Consortium to take it over. 

BIND is still the primary distribution of DNS, although there are other distributions now. For example, Microsoft added DNS in 1995 with the release of NT 3.51. 

But back to the 80s real quick. In 1985, came the introduction of .mil, .gov, .edu, .org, .com TLDs. Remember John Postel from USC? He and Joyce K Reynolds started an organization called IANA to assign numbers for use on the Internet. DNS Servers are hierarchical, and so there’s a set of root DNS servers, with a root zone controlled by the US Dept of Commerce. 10 of the 13 original servers were operated in the US and 3 outside, each assigned a letter of A through M. You can still ping These host the root zone database from IANA and handle the hierarchy of the TLD they’re authoritative for with additional servers hosted for .gov, .com, etc. There are now over 1,000 TLDs!

And remember how USC was handling the addressing (which became IANA) and Stanford was handling the names? Well Feinler’s group turned over naming to Network Solutions in 1991 and they handled it until 1998 when Postel died and ICANN was formed. ICANN or the Internet Corporation for Assigned Names and Numbers, merged the responsibilities under one umbrella. Each region of the world is allowed to manage their own IP addresses, and so ARIN was formed in 1998 to manage the distribution of IP addresses in America. 

The collaboration between Feinler and Postel fostered the innovations that would follow. They also didn’t try to take everything on. Postel instigated TCP/IP and DNS. Postel co-wrote many of the RFCs that define the Internet and DNS to this day. And Feinler’s showed great leadership in administering how much of that was implemented. One can only aspire to find such a collaboration in life and to do so with results like the Internet, worth tens of trillions of dollars, but more importantly has reshaped the world, disrupted practically every industry and touched the lives of nearly every human on earth. 

Thank you for joining us for this episode of the History Of Computing Podcast. We hope you had an easy time finding thanks to the hard work of all those who came before us.