Word Notes 11.22.22
Ep 126 | 11.22.22

Domain Naming System (DNS) (noun)


Rick Howard: The word is: DNS

Rick Howard: Spelled: D for domain, N for naming, and S for system 

Rick Howard: Definition: A system that translates text-based URLs to their underlying numerical IP addresses. 

Rick Howard: Example sentence: The user was connected to the website after the DNS query found the address, 

Rick Howard: Origin and context: The Domain Name System, or DNS as the cool kids call it, converts the English sounding website destinations or URLs that internet users type into their browsers like The CyberWire.com into IP addresses that the underlying computers and routers use to direct internet traffic.

Rick Howard: According to Andrew Blum, in his excellent history of the internet called "Tubes," in 1969, the Stanford Research Institute and UCLA connected the first two computers over a phone line. And as Blum says, the internet took its first breath that day. Since then, it has been exponentially growing. In those early days, early 1970s, network managers passed around a file named hosts.txt, maintained by SRI International that listed all the names and associated IP addresses on the internet.

Rick Howard: Users would type the name of the computer they wanted to connect to, and the application would look up the IP address on the local machine. By the early 1980s, there were some 300 computers on the internet, and it was clear to all the internet pioneers that the hosts.txt file solution wouldn't scale. They needed an automated distributed system that could grow and shrink as machines came on and left the internet. 

Rick Howard: Paul Mockapetris in his first job outta grad school working for USC's Information Sciences Institute designed the Domain Name System in 1983 and in 1986, the Internet Engineering Task force IETF, made Mockapetris' design one of the early internet standards. 

Rick Howard: The DNS system consists of four DNS server types. Now bear with me, this gets a little complicated. If you're keeping score at home, you might want to write this down. Here are the four, the recursive resolver, the root server, the top level domain name server, and finally the actual domain name server.

Rick Howard: Let's start at the top, number one, the recursive resolver. When you type The CyberWire.com into your browser, you are essentially sending a request to the DNS, asking for the IP address of The CyberWire.com. The recursive resolver knows where to look to find the answer.

Rick Howard: Number two, the root server. The recursive resolver contacts the root server for the .com domain. The root servers are the authoritative source for top level domains like .com, .org, .Net, et cetera. As of August, 2022, there were some 1,487 top-level domains or TLDs registered in the system. There are thousands of root servers scattered around the world for each top level domain to make sure the queries are answered quickly. The root server sends back to the recursive resolver, the IP address of the top level Domain Name Server that can help answer the question. 

Rick Howard: Number three, the top level domain name servers, top level domain name servers, or TLD name servers for short, store information for second level domains, like The CyberWire.com. .Com is the first level, The CyberWire.com is the second level. In other words, TLD name servers don't store the actual IP address of The CyberWire.com, but they know where all the domain name servers are that have that information. The recursive resolver now asks the TLD name server for the IP address of the actual domain name, server of The CyberWire.com.

Rick Howard: Number four, the domain name server. The domain name server stores the actual IP address for The CyberWire.com. The recursive resolver asked the domain name server for The CyberWire.com IP address and receives it. Finally, the recursive resolver sends the IP address to the browser, and now the browser can travel to The CyberWire.com web page and render the site.

Rick Howard: Phew, that was a lot. When hackers attack the domain name system, they either try to manipulate it into causing a denial of service attack of some sort. Use the DNS protocols to hide their attack sequence across the intrusion kill chain, or spoof the DNS traffic to trick the victim into visiting a malicious site. 

Rick Howard: Nerd reference: On the History Heard YouTube channel, back in 2009, the host interviewed Paul Mockapetris about the creation of the domain named system.

Paul Mockapetris: What started was, uh, back in the early eighties, uh, John Costell walked in, he was my boss, walked into my office and said five people had these ideas for ways to do a distributed registry, distributed phone book of the internet, if you will, and could I kind of take a look at all the proposals and create a compromise? Um, but basically what I did was I stole the name off of one of them and then put my own stuff, and nobody seemed to notice. Uh, there's a common story about a lot of the stuff that happened in the, in the internet is that, uh, people got the job to do something and had so much fun doing it because nobody at the time thought it was important and it was clear cuz I was a recent graduate and this was a nice little project where all of the, while all of the important people were off doing other things. Now it turned out to be a very important thing. Um, but nobody at the time thought it was. You know, the influences that shape the work, people usually say, well, I took those five proposals, but in reality it was work that I had done earlier at, uh, at MIT with, uh, Nicholas Negroponte and the architecture Machine folks and a bunch of other influences ahead that sort of shaped my thoughts and this just, and it, they gave me a blank sheet of paper and thought I was supposed to copy onto it and I didn't. So that's how I got to do it. Um, over the years, now, if I take a look at it, the way to think about it is I maybe built the basement and first floor of a building and other people have added 10, 20, 30 stories on top of it. So when you look at it all and all of the things that it's used for and so forth, a lot of that's been done by other people after I kind of did the first steps and so that's how we got to where we are today. 

Rick Howard: Word Notes is written by Tim Nodar, executive produced by Peter Kilpe, and edited by John Petrik and me, Rick Howard. The mix, sound design, and original music have all been crafted by the ridiculously talented Elliott Peltzman. Thanks for listening.