Can someone explain what a DNS *is* and how it works, what it does?

  • MikeW

    Posts: 6061

    Jul 14, 2014 2:04 PM GMT
    This is in relation to JackBoneTX's thread and how it fixed Art_Deco's problem (as the rest of us more or less eventually got the site back on our various devices).

    I know what "DNS" stands for and have a very vague idea of how it works but it is far from clear to me. I understand that the DNS network translates alphanumeric domain names into IP addresses.

    I did NOT know that one could change one's DNS settings to something other than those provided by one's ISP.

    How does *that* work? I *assume* the DNS setting is itself an IP address--but how is it that you can change a provided DNS to some other number? What is happening when you do that??

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    Jul 14, 2014 2:58 PM GMT
    It's just a configuration, an IP address you enter into a box. Your system uses the configured IP addresses of the DNS servers to translate an alphanumeric host name to a numeric IP address. Your system sends the DNS server the string a.rjstatic.com and the DNS server returns its IP address and then your system gets or sends whatever it needs using that IP address. The internet only uses IP address; the alphanumeric names are for our convenience.
  • AMoonHawk

    Posts: 11406

    Jul 14, 2014 3:04 PM GMT
    DNS stands for Domain Names Server ... it is a node/server that has a list of nodes names that match to an ip address. You can change it on your local network to what ever you like but when you sign in to your isp (internet service provider) you will get assigned an ip address until you sign off, it is not really going to care what the name of your node is. It would only matter if your node was a server on the isp network. I believe every computer does have a hard a coded identification that you cannot change, but I forget what that is called. That should be it in a nutshell. I'm not much of a networking guru, but I'm sure if you want to know more, you can find some good networking sites that can explain with a lot more detail.
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    Jul 14, 2014 3:11 PM GMT
    What *I* don't understand is why, in the case of RJ, I had to manually reconfigure the DNS. When I've never had to do this before.

    Not ever, and I've been using the Internet since its dawn. And proprietary dial-ups before that. So I'm not exactly a novice with online.

    I kinda understand what a DNS does, but I don't understand why it's always been automatic, until now. No other site ever made me do that. icon_razz.gif

    BTW, my thanks again to JackBoneTX for giving me the solution. RJ Admin sure didn't. At first I was irritable and cranky about the whole deal, and more than dubious. But I was finally able to figure it out for my devices, and you can't argue with success. icon_biggrin.gif
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    Jul 14, 2014 3:30 PM GMT
    Art_Deco saidWhat *I* don't understand is why, in the case of RJ, I had to manually reconfigure the DNS. When I've never had to do this before.

    Because the "real" DNS server for a particular system is managed by what's called the authoritative DNS server, generally the ISP for that server. All of the other DNS servers, e.g., your ISP, keep a copy of the IP address they got from the authoritative server.

    So your desktop computer asks for the IP address of a.rjstatic.com; it asks your ISP's DNS server, your ISP's DNS server in turn requests the IP address from the authoritative DNS server (although I don't remember or understand how it knows which one is the authoritative DNS server), after your ISP's DNS server gets the IP address from the authoritative DNS server it returns it to your desktop computer and also saves it for future reference in case your desktop computer asks for it again. After a while, e.g., a day, it's supposed to throw away this saved IP address and go back out to the authoritative DNS server and get it again.

    In this case it sounds like the IP address of one of (or all of) the rjstatic servers changed; e.g., from 1.2.3.4 to 10.20.30.40. But your ISP's DNS server was returning the old IP address, which pointed to a nonexistent server.

    I'm not sure why google's was returning the new IP address and your ISP was returning the old one. Above, when I said, "After a while, e.g., a day" that "day" is a configured parameter called the Time To Live (TTL). When the authoritative DNS server is queried it returns both the IP address and the TTL, and then your ISP's DNS server should go back to the authoritative DNS server for a possible update to that IP address after the TTL has expired.
  • MikeW

    Posts: 6061

    Jul 14, 2014 3:51 PM GMT
    Lumpyoatmeal said...In this case it sounds like the IP address of one of (or all of) the rjstatic servers changed; e.g., from 1.2.3.4 to 10.20.30.40. But your ISP's DNS server was returning the old IP address, which pointed to a nonexistent server….

    Thanks, Lumpy, you answered my question. And, yes, this is what happened because a.rjstatic and d.rjstatic changed hosts. Apparently Art's DNS was holding the old IP address.

    Learn something new every day. icon_razz.gif I just didn't know that one *could* change the server IP addresses to something other than those provided by the ISP and have access still function.
  • Lunastar

    Posts: 328

    Jul 14, 2014 4:02 PM GMT
    I was expecting some gay sex acronym. I've been conditioned icon_sad.gif
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    Jul 14, 2014 4:15 PM GMT
    Well, DNS also means dominant noisy sucker, but you probably can figure out how that works and what it does.
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    Jul 14, 2014 6:54 PM GMT
    MikeW said
    Lumpyoatmeal said...In this case it sounds like the IP address of one of (or all of) the rjstatic servers changed; e.g., from 1.2.3.4 to 10.20.30.40. But your ISP's DNS server was returning the old IP address, which pointed to a nonexistent server….

    Thanks, Lumpy, you answered my question. And, yes, this is what happened because a.rjstatic and d.rjstatic changed hosts. Apparently Art's DNS was holding the old IP address.

    Learn something new every day. icon_razz.gif I just didn't know that one *could* change the server IP addresses to something other than those provided by the ISP and have access still function.



    When you change the primary, secondary DNS settings in a device, The instructions specifically say NOT to change the ISP's IP address, as it is static. You are only changing the primary, secondary numbers

    Not sure about ATT yet, but when I had TWC, time warner would periodically change its IP address through its remote router reboot process
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    Jul 14, 2014 7:02 PM GMT
    Lunastar saidI was expecting some gay sex acronym. I've been conditioned icon_sad.gif


    haha
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    Jul 14, 2014 7:27 PM GMT
    Lumpyoatmeal said
    Art_Deco saidWhat *I* don't understand is why, in the case of RJ, I had to manually reconfigure the DNS. When I've never had to do this before.

    Because the "real" DNS server for a particular system is managed by what's called the authoritative DNS server, generally the ISP for that server. All of the other DNS servers, e.g., your ISP, keep a copy of the IP address they got from the authoritative server.

    So your desktop computer asks for the IP address of a.rjstatic.com; it asks your ISP's DNS server, your ISP's DNS server in turn requests the IP address from the authoritative DNS server (although I don't remember or understand how it knows which one is the authoritative DNS server), after your ISP's DNS server gets the IP address from the authoritative DNS server it returns it to your desktop computer and also saves it for future reference in case your desktop computer asks for it again. After a while, e.g., a day, it's supposed to throw away this saved IP address and go back out to the authoritative DNS server and get it again.

    In this case it sounds like the IP address of one of (or all of) the rjstatic servers changed; e.g., from 1.2.3.4 to 10.20.30.40. But your ISP's DNS server was returning the old IP address, which pointed to a nonexistent server.

    I'm not sure why google's was returning the new IP address and your ISP was returning the old one. Above, when I said, "After a while, e.g., a day" that "day" is a configured parameter called the Time To Live (TTL). When the authoritative DNS server is queried it returns both the IP address and the TTL, and then your ISP's DNS server should go back to the authoritative DNS server for a possible update to that IP address after the TTL has expired.

    OK, my head hurts.. My outage was over 36 hours, which doesn't seem to fit your model.
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    Jul 14, 2014 7:35 PM GMT
    I used to have a pretty good illustration/explanation of DNS. I'll see if I can find it when I get home.
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    Jul 14, 2014 11:54 PM GMT
    Lumpyoatmeal saidWell, DNS also means dominant noisy sucker, but you probably can figure out how that works and what it does.


    OMG icon_lol.gificon_lol.gif
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    Jul 15, 2014 12:03 AM GMT
    Some of this was already said, but here's my understanding in a long-ass paragraph:

    DNS allows humans to use words like www.aol.com instead of IP addresses like 48.38.184.1 to access sites on the Internet. DNS servers do this translation for us. They're like phone books or directories. And rather than have one, authoritative server, which would be a large point-of-failure if it went down, anyone can run a DNS server and add it to the chain of thousands that are in use. These servers regularly talk to and update (propagate) each other, sharing information on what the current viable addresses are. But since new sites are always being made or going defunct, sometimes there's a noticeable delay in the chain. Your computer accesses these servers transparently every time it needs to, like when you're browsing web sites, but by default it will likely use the DNS server of whoever is giving you your connection. All we did here was to switch the DNS server our computers were looking at and which were being slow with the RJ change, switching to a (probably) more reliable and up-to-date directory, Google's DNS servers.

    I think.
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    Jul 15, 2014 12:54 AM GMT
    I couldn't find the image that I saved from a while ago. But this one is pretty simple and straight forward.

    adlooPx.gif