Explaining the Domain Name System

DNS records, name servers, and other aspects of the Internet’s domain name system (DNS) explained. Video illustrates DNS operation, and also includes examples and discussion of NS, A, AAAA and other DNS record types.
If you find this video useful, you may also be interested in my introductions to HTML and CSS, as follows:
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More videos on computing and related topics can be found at:
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Chapters:
00:00 Introduction
00:51 DNS Operation
04:08 Domains, Name Servers & DNS Records
07:46 Adding a Website
10:20 DNS & E-Mail
11:06 Wrap
#DNS #Nameserver #DNSrecords #ExplainingComputers

[@richjamjam]

As someone who runs a global DNS platform for a large UK web host, I can say everything in this is spot on 👍🏻. DNS has lots of gotchas, but for general people's understanding who want to know that bit extra about their web or email hosting DNS, it's perfect.

[@ExplainingComputers]

Thanks for your kind and reassuring feedback. :)

[@governmentcheese2257]

Agreed ! I admin a large corp dns structure and Im hoping to send this vid to coworkers that have interest in how dns works.

[@autohmae]

As someone working at a hosting provider, I agree. I do wonder for how many people "the Internet's phone book" will be a clear description in the coming years/decades. 🙂 7:33 if I had to really nitpick, seems to me it's: "can be kept in cache" instead of "should be kept in cache" (English is not my first language). And we could obviously get into the weeds and say: well, in practice part of the recursive nameservers use QNAME-minimisation, etc. But that's clearly off-topic for such a video.

[@ExplainingComputers]

Great point on "phone book". :) I had not thought of that.

[@johnm2012]

​@@ExplainingComputersLast week I received what was labelled as the very last paper edition of my local telephone directory. I was going to put it in the recycling but I decided to hang on to it for posterity!

[@michaelwright2986]

Getting things that clear takes a special talent and a lot of work.

[@bramfran4326]

Nice. You could also have mentioned that domain names are read from right to left, from the more general word to the more specific one. I found it enlightening when I learned about this.

[@DoctorOnkelap]

in emailaddresses it is reversed

[@idowebwork]

Been dealing with DNS and all things web for over 25 years. Absolutely spot on & well explained, as always.

[@ExplainingComputers]

Many thanks. :)

[@auto117666]

A video I can really ‘dig’ into! From a security perspective, this is where you can see how the original developers of the internet really did not think about things like, “What happens if a someone sets up their own DNS server and lies about which IP their domain belongs? What if the client gets the wrong information first?”

[@autohmae]

What system would you have suggested ? Because they were very different times.

[@richjamjam]

Love the play on words! ;)

[@harleyn3089]

The funny thing about a lot of long term solutions is that they started out as "temporary" solutions. When the internet first started, there was no DNS system. There was a host file that had a list of all the names that you knew about, and the IP addresses that went with them. People would share this host file with each other, which started getting larger and larger as more sites were added to the 'net, So to centralize the resolution of host names, someone wrote a system called "hostd", which was a UDP based way to communicate the information in the host file. This gradually grew into the DNS protocol that we use today. Much like the streets in a city, not everything was planned out in advance. The internet grew organically based on what was needed. Back when the internet was a few thousand users, nobody really had a true sense of how big and ubiquitous it would become. I'd say DNS has done pretty well as a technology considering its roots.

[@Sylvan_dB]

"dig" (ISWYDT) Why would the client decide to talk to the malicious DNS server? DNS queries are directed, not broadcast. The client will only send those queries to the DNS server it is configured to use. Usually the next question involves spoofing or malicious DHCP to push an incorrect DNS configuration. If that is possible, your network is set up like we did it in the 1980s, and not for secure access the way we've learned to do it in the 21st century. Never the less, if it happens, the client will get bogus information back from the malicious DNS server. The client might attempt to validate that information but that is still treated as optional a lot of the time. Then when the client attempts to contact the address it received from the DNS, it might fail if the address is unreachable, or assuming the address is 'live' then you better hope that your connection is using TLS to verify the service contacted has a certificate from a valid certificate authority (CA) for the host which matches the hostname you expected. Look for the padlock in the browser address bar, and don't just ignore the warnings about invalid certificates.

[@tonysheerness2427]

What amazes me is not how it works but how quick it happens.

[@ExplainingComputers]

Agreed! It is amazing. And we just take it for granted.

[@StolenJoker84]

I was thinking the same thing - especially the number of steps needed for a “new” request where nothing is cached.

[@marpintado]

The process only uses 2 very short UDP packets for every single interaction. It is a so well taught mechanism, it still works as defined in November 1987.

[@tonysheerness2427]

Maybe but when you are reading web pages from 15,000 miles away it is very impressive.@@marpintado

[@silentios7336]

Its always good to see someone trying to explain "easy" things to the common people. Keep up the good work.

[@MatthewHarrold]

My dad had a 80's folk band with a trumpet player who was a very clever person. He created the Trumpet Winsock over TCP/IP, and made a fortune with Microsoft. He also ran an ISP called TrumpNet in Tasmania (my home island). Irrelevant trivia mode OFF. $0.02

[@marcdraco2189]

I actually used Trumpet! How about that ?! Small world.

[@markwhidby5148]

Me too! There's a Wikipedia page for Trumpet Winsock and Tattam Software Enterprises still have a web presence.

[@richjamjam]

That's awesome!

[@iPondR]

So happy to be a channel member!! This is a topic I've wanted to know about... but didn't know it! Thanks! :D

[@ExplainingComputers]

Thanks for watching. :)

[@watsoft70]

Spent years in IT and still learning! Thanks Christopher for enlightening someone that appreciated what goes on, but never worried about the mechanics of it. 👍🏻

[@0_1_2]

Don’t worry, eventually you’ll reach the point where you know everything and there’s no new technology to learn about.

[@MichelMorinMontreal]

A new masterclass to help you understand everything about DNS in 12 minutes! It's got to be done! And it's done! A video to be circulated among geeks and digital students alike. Personally, I learned a lot, so thank you very much.

[@perrymcclusky4695]

Wow, interesting to see what is behind the curtain! Looking forward to your next video!

[@ExplainingComputers]

Thanks Perry. The next video could not be more different! :)

[@perrymcclusky4695]

Can’t wait!

[@dankierson]

Short and sweet. It might have been useful to also outline the various data kept on domain owners and the visibility of such data to the Internet public. Email deserves a video of its own - as does the 3 DNS records needed for smooth transmission of email. One topic really needing a comprehensive video is how to set up your own email server on a VPS, interface it with both a mail delivery agent (plus mail user agent or email client) and a webmail server. Oh to be independent 😊

[@chriholt]

Thank you Chris (as always). I have had to learn all of these gory details as "on the job training" which I don't regret at all, but it is great to see these explained so clearly!

[@MicrobyteAlan]

Timely, I need a website for my future 3D Printed, Laser cut, and etched projects. Interesting and well presented. Thanks as always.

[@ditzydoo4378]

This has been one of the most simple and complete explanations I've ever received on this subject. Thank you for posting this.

[@beltanewalk8797]

Another cracking episode explaining a complicated subject in a clear and understandable way. Or rather as clear as possible, given the obligatory jargon and acronyms that comes with anything I.T.

[@dcc1165]

Your teaching experience and prowess shine through very brightly in these instructional videos. I've seen the same content presented in other videos lasting twice as long, but always evoke more questions than they answer. Having said that, I've administered DNS in some capacity ever since its inception back in the '80's, so I think a more deep-dive video of the various DNS record types and their uses would be beneficial to many users.

[@CCoburn3]

Good video. I can hardly wait until next week for the “surprise” video.

[@AMDRADEONRUBY]

Nice a useful video about DNS have a nice one

[@brianwood5220]

Brilliant, Chris. I appreciate all the time and research you put into finding out what makes the internet tick. Thanks for sharing.

[@stevebrown1974]

I first learnt about DNS 20 years ago and still find it incredible that the exchange between the device, ISP DNS resolvers and other DNS servers all takes place between when you press Go (or Enter) in the browser and the second or 2 later when the webpage appears, sometimes it's a blink of an eye!

[@slicedpage]

blows my mind too. I think it is an age thing. Never mention "Dial-up" the Z gen will laugh at us.

[@autohmae]

As someone who has worked on optimizing website delivery to browsers: if it takes 2 seconds that would be a disappointment for me if I had worked hard on a site. 🙂 (at least on wired desktop, WiFi laptop/tablet or especially smartphone would be different, 4G has a much higher delay/latency than 5G, 5G is a big upgrade in that regard).

[@ExplainingComputers]

Sadly the art of factoring loading time into web page design seems to be dying.

[@autohmae]

@@ExplainingComputers Luckily some of the underlying technologies really help, Like HTTP2 and TLS/1.3 and QUIC greatly help with that. HTTP2 reduced the overhead over HTTP so much it basically nullifies the overhead of TLS/HTTPS. And TLS/1.3 and QUIC greatly help reduce the overhead in case of lower latency connections like WiFi, 4G or crossing the oceans. The new HTTPS-record is now also being deployed and actually used by modern web browsers. Making it possibly to having browsers directly connect by using QUIC. And more and more people understand you need to to use caching when using something a CMS like Wordpress. Obviously that doesn't help prevent silly things like the problem of someone uploading their photos directly from their DSLR camera on their Wordpress site without optimizing it for the web. 🙂

[@DoctorOnkelap]

I've noticed that sites in certain countries tend to load slower. I guess that is because the process described in this video takes a less direct route and more intermediates are necessary before all details are resolved together with a decreased probability of parts already being cached more locally.

[@msulemanf]

Just love this channels direct approach to delivering value.

[@ExplainingComputers]

I appreciate that!

[@daboogiemansass]

As always I love your sane delivery of correct information!

[@silverback3633]

Thanks for explaining that a layman like me can grasp an inkling of how it works. You are truly an Explaining Computers. My uncle was a postmaster in the mid-century when telephone and telegraph systems were integrated. Having played with the telephone switching console to the Morse code keyer, I am still wondering about all the protocols from sending registered mail to sending and receiving telegraphs, and how they all worked. Next may be how the internet search works.

[@SkyFly19853]

I love those videos that explain things in details with clear definitions.

[@johncundiff7075]

Very interesting-AS ALWAYS- Thanks for all the hard work and detail time you put in every day!

[@aperrao]

excellent topic...is always good to refresh tha basics on how the internet works....Thanks

[@joeg3950]

Thank you for the video. I just started my own website and had a crash course in some of these topics. Very helpful video.

[@Colin_Ames]

Fascinating stuff. Porkbun is an interesting name for a domain registrar, although as I’m from Coventry I think it should be Porkbatch (preferably with stuffing) 😊.

[@martinsmith5028]

Hi Chris, very informative. Thoroughly enjoyed it 👌

[@jls9225]

Excellent beginners tutorial on how DNS works. Have a good rest of your weekend Christopher. As Always, Be Smart and Stay Safe.

[@alanthornton3530]

This was an absolute eyeopener for me, I never realised just how much goes on behind the scenes accessing websites/sending emails. Thanks Chris for a thoroughly well explained video, it's good to see the positive feedback from people in the know. :)

[@williamhorton9763]

A mere twelve minutes of EC is better than two hours of the other tech channels.

[@ExplainingComputers]

:)

[@MichelMorinMontreal]

I couldn't agree more!

[@jameswubbolt7787]

Always the best subjects. Thank you.

[@MKMforJesus]

I’ve been waiting for you to make a video on this😂🎉

[@gam85191]

Thank you Chris! Very informative!

[@jacobofraiz]

Great divulgation video. Thank you.

[@Rivenworld]

Brilliantly explained Chris, thank you for sharing this. Always love your videos. 🙂

[@k-c]

Nobody else explained this better to me than you. Thank you!!!

[@antonyrodriguez5621]

These little guides are convenient, to say the least!

[@fram1111]

Even if you know well you're about to explain you give it a special pizzazz in a touch of you're own. To give us especial look at the world of DNS. Well that's it for now until next time! Another great video for the archives. Decades from now I predict your KZbin channel we become the most used educational tool did teach history of computer science.

[@mikelincoln8395]

Cheers! Thanks for all the time and effort you put into these videos.

[@beardedlady6291]

Thanks Christopher, great to show this to my kids to get them ready for a great career.

[@brentsmithline3423]

Brought me back to years gone by as sysop/sysadmin at a small regional ISP when everything was done with vi text files on Sun Solaris UNIX host systems.

[@Kw1161]

Thanks Chris for your informative video, it makes the process more clear, but it still feels like I am reading a legal document….😂! Have a great week!

[@ObsidianMercian]

Thank you Chris, brilliant video!

[@bobwong8268]

👍👍👍👍👍Simply Great - another Awesome master piece; Thank You Chris! Complexity Explained Simply

[@kueifengtung2693]

This was fun, please more on dns records :)

[@MarcelHuguenin]

Excellent video! I love the way how you explain this matter.

[@insanemainstream3633]

Another fantastic video Chris!

[@procta2343]

I studied this when i did windows 2003 server, it really went in depth. to the point you can write your own cheques

[@lesliedeana5142]

A short, but concise coverage of a somewhat difficult subject. (Primarily due to so many little differences between the various control panels.)

[@ExplainingComputers]

Greetings Leslie. Standardization would be helpful indeed!

[@mikefinn2101]

Great well done simple explanation of DNS Love your channel wish I knew as much as you or was a smart as you but your very kind to explain this. Few are so nice your a rare teacher super thanks

[@badisheffey4550]

Thank you @ExplainingComputers. Great video as per usual; I’m a bit surprised that this topic wasn’t covered previously however. Keep it up good sir!!

[@ExplainingComputers]

I've been putting off making this video for years! :)

[@onlyyou200548]

very helpful video. thank you!

[@dylanwilsonYT]

Great video Chris! Learnt a lot from this one. :)

[@k4be.]

"Glue" records are even more fun!

[@13thravenpurple94]

Excellent video 👍 Thank you 💜

[@loginregional]

Very enjoyable to relive those heady days. I have the CL domain EN as well as others. Berkeley Internet Name Demon (or Daemon). Imagine, a barebones clone 4meg, no X, getting all the services up, BSOD overflows on Win95 over IRC; Linux sumpin 0.7 I forget. Yggdrasil, doz CD. *THE GOOD OLD DAYS* when it was freeeee. Back then it was CAFE domain way back

[@RoboNuggie]

Excellent explanation and I now appreciate the way things work more than I did.... I also learned what CNAME stood for.... so I thank you for that 🙂 Cheers Chris!

[@ExplainingComputers]

Thanks for your support. :)

[@lastinline1958]

Thanks for another soporific discussion.

[@gedgicat2063]

Great video, love to see things like this, hope there will be a follow up at some point 👏

[@DoctorOnkelap]

yes, a followup about the dark web for instance.

[@HyperspaceQ]

Stellar, Christopher!

[@mbhinkle]

Great idea and execution for a show. 😃

[@Uniblab8]

Very involved and worth the price of admission to view a video such as this, I admit I an an idiot when it comes to these processes so I say kudos on another great video.

[@ronm6585]

Thanks for sharing.

[@sirdaemon5338]

Really good video thanks

[@davepickering997]

Thank you, very well explained. So now you know why support desks insist on clearing the cache even though the process is not easy or clear (and hidden). It can be done from a command line but.... Your average user will not have the skills and worry that the rest of their stored data will be lost.

[@AllensTrains]

You might like to make a video explaining how to set up a DNS and web server on a Raspberry PI, as some people in their bedrooms would not be able to pay a subscription! Thanks for uploading.

[@vishnusuraj9914]

Thank you very helpful and useful 👍👍👍❤❤❤❤⭐⭐⭐⭐⭐

[@gosnooky]

Fun fact: Amazon's Route53 service is named as such because "53" is the default port for DNS.

[@gloiloidn5752]

Thanks a lot! I was trying to read a book on WWW. This video helped me as well as inspired me to go a bit deeper and understand the World Wide Web.

[@z3r0c00l2]

Excellent video ...My second job is web hosting / stream broadcasting 😊

[@innerfinder100]

Thank you the next video should be how to setup your oun server in a SBC

[@pauld7827]

I have always explained to people that DNS is like a phone book also!

[@kevgermany]

Thanks, very useful. Would be good to follow ip with an overview of the https extra needs.

[@freckhard]

I am saluting and applauding you for your very well explained video! I always watch your videos even if I assume I know the topic (which in this case I fortunately do) but it is like everyone's saying again perfectly spot on! Thank you for this teaching-masterpiece again! I have a question regarding timestamp 9:30 the CNAME has a dot "." after the com, is this how it is with your registrar to indicate the end of the domain, or is this just by accident, as I have not seen this before? 🙂Thank you and see you next video!

[@ExplainingComputers]

All domains technically end with a dot when they are what's called "absolutely fully-qualified" (unambiguous). Entering them in this way in a DNS record data/value field is pretty common.

[@freckhard]

@@ExplainingComputers That makes perfectly sense, thank you for elaborating! Cheers

[@CARLiCON]

Thanks EC, great DNS info here. Another similarly interesting topic would be VPNs, if you haven't covered these yet

[@ExplainingComputers]

Yes, you are right. VPNs is another pending topic! :)

[@bnrid8086]

more about networking please 🙂

[@ExplainingComputers]

Noted!

[@NomadicSage]

Another interesting and informative video, thanks Chris. Can you also make a video on ENS and the newer web3 hosting

[@ExplainingComputers]

Noted.

[@abdullahalhalabi1]

Amazing video

[@ExplainingComputers]

Thanks!

[@trevorford8332]

I've been trying to figure out how DNS work for ages, as I want to configure my own localhost email server. I hope your video helps. 😊

[@ExplainingComputers]

Good luck!

[@richjamjam]

If you're a Linux guy, I recommend Exim as your MTA and Dovecot as your delivery agent and IMAP server. Get that working for virtual users locally, and then just set the MX record to your WAN IP and setup some port forwarding :)

[@procactus9109]

It would have been good to hear about DNSs weakness and how it can be used against us

[@rohitdoestech]

Running an email server from the home is a tricky thing to do, fun but not great as well!

[@4ryan42]

Shoutout to everyone running their own DNS resolver at home on a raspberry pi (Pi-Hole here).

[@ffieditor]

nothing like making the top 100. there is so must to forget!

[@adunford2664]

Very well explained video. Are you able to do a similar one on home Wi-Fi routers and the latest standards?

[@ExplainingComputers]

I did a video on Wi-Fi standards earlier in 2023 -- kzbin.info/www/bejne/h4TUYoePic54iaM :)

[@jaffarbh]

Gone the days when organisations (including SMEs) used to host their own Exchange server and Active Directory on prem and thus internal DNS servers :)

[@srvuk]

A tough one to get across in a complete manner.

[@leetucker9938]

awsome

[@alichohan1999]

Sir please make next video on How to run your own web server at home or at Enterprise level. With complete details. 8:14

[@semuhphor]

HI Christopher! Cool video. It was well explained and graphically excellent. I did have one question. Is a full email address send to the resolver or does the PC strip off the part up to the "@" and only request the domain? I don't think DNS is involved in resolving this part of the address. Using nslookup on macos, if I sent my full email address, it returned an error while sending the domain name worked as expected.

[@ExplainingComputers]

Yes, you are right -- the resolver will only search for the domain after the @ symbol. I should only have the user@ in the lower part of the e-mail diagram (where the message is being directed to the final server.

[@giantisopod]

The most confusing thing about DNS to me is that the NS records themselves contain domain names. So you need a DNS server to resolve a domain, but then you need to resolve a domain to get the DNS server.

[@mkcristobal]

Another very instructional video, as always 👍🏻 I think you didn't mention that web browsers usually also have a DNS cache, so when you are trying to flush all dns caches to do educational research, like observing DNS traffic using Wireshark, you have to remember to flush the browser's cache, the OS cache and try to enforce the use of an administrative authority server or whatever that was called, can't remember 😅 Anyway, it was all very practical and well explained

[@ExplainingComputers]

Thanks for this. I did mention the cache on the computer itself (ie in the brower) - just after I talked about DNS resolver cache.

[@happyputt9709]

Thanks

[@Chris.Brisson]

I've always wondered why my router, which dolls out IP addresses to clients on my LAN, has trouble resolving the names of the clients (many of them listed with a Host Name of "Unknown". Why doesn't a router use a hosts file that I can edit. I'm thinking it is not a good thing to have so many mystery clients attached to my network.

[@zacmitchell_1984]

Say domain name 5 times fast😅 Jokes aside, thankful for this video. Networking has always been Greek to me!

[@privacyvalued4134]

Hosting your own website is a lot of work. It's not for everyone. However, shared hosting has tons of limitations and ultimately costs about the same per month as a good cheap VPS solution. The general rule of thumb though with regards to website hosting is to not put all your eggs in one basket. That is, the domain registrar should always be separate from the hosting provider. So many horror stories exist of people who bundled everything and wound up in a situation where they lost everything.

[@FranklyPeetoons]

It happened to me. I had everything related to my website tied up in one small company for 19 years. How small? One guy, in another country, who moved often and didn't keep careful records. He died suddenly. He left behind no plan for what would happen in that eventuality. I tried calling the contact number and reached only a bereaved mother who knew nothing. My website and email were soon gone. It took months to get it straightened out and reclaim everything. Now I'm set up with a more conventional web hosting/registrar business, with a proper plan in place should anyone cease to be.

[@privacyvalued4134]

The one thing you didn't cover is backups. Backing up DNS records is something that few people think about doing. If you have a simple setup of one domain and a handful of records, it's probably not too difficult to restore in the event of any issues arising. However, even small businesses have hundreds or even thousands of DNS records and a company like Microsoft maintains a portfolio of tens of thousands of domains and hundreds of thousands of DNS records. Backing up DNS records becomes more essential/mission critical as more records get added for various purposes. Backing up web servers is its own separate topic too.