Downtime: I hope you can read this

By Shamus Posted Monday Jan 17, 2011

Filed under: Notices 103 comments

splash_modem.jpg

Welcome to 1996. Please enjoy your internet.

I’m sure you’ve noticed that my site tends to go down a lot. It turns out this blog is a resource pig. According to my webhost, I had an entire machine to myself and it was still going down on a regular basis. About two or three times a month the machine would be overwhelmed for a few hours and the site would vanish. I could never get a definitive answer out of them if the cause was bandwidth or CPU usage. Bandwidth seems unlikely – this site isn’t that popular. I’ve survived simultaneous links from Slashdot and Make. But if the cause is a PHP script that runs amok, I’m at a loss to find it.

But last week they moved me to a new server, in hopes that this would improve things. I also installed supercache, which might help lighten the load. I’m very disappointed that web hosts track bandwidth usage but don’t give you any way of tracking CPU usage. It means I’m working blind and have no way to really look for problems.

But anyway. The site moved. This meant a new IP address. Which meant we needed to wait for the DNS to sort out.

IP address is your unique address on the internet. Everything on the net has one. You can go up to the address bar and type in http://128.242.240.84 and go to that website. In the very early days of the network, this is how it worked. Then people pointed out that keeping track of IP’s was a chore, and they came up with the idea of making a handy alias for all these DOZENS of numbers. So instead of remembering 128.242.240.84 you can remember twitter.com.

But then you need a system of looking up domains and seeing what IP they have. A kind of phone book for the internet. Since the network is headless, keeping everyone on the same page can get messy. Your ISP generally provides a domain name server that does this looking up for you. So when you look up Twitter, it looks up the IP for you and sends you the result.

This DNS is only supposed to store the IP for so long – if you ask for the same site again tomorrow, it’s supposed to look it up again, just in case the site moved.

Now, the last time this site moved the DNS sorted in a couple of hours. But this time it dragged on for over a day. Other people were having the same problem. A lot of people. I switched to using the Google DNS servers, which fixed things for me. But other people still couldn’t reach the site for days.

As far as I’ve been able to learn, this is 100% the fault of rotten ISP’s. If you couldn’t reach my site for more than a day, it means your provider was ignoring the proper DNS procedures and giving you my old IP, even days later. As of yesterday, I was STILL getting messages from people who couldn’t reach the site. This is ridiculous by any standards, and even the internet of 1996 was more robust than this.

So that’s where the site went. I imagine that this should all be sorted out eventually. Sorry for the downtime. Hopefully we’ll see less of it in the future.

 


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103 thoughts on “Downtime: I hope you can read this

  1. Nick Bell says:

    For those who are interested, it is generally possible to set your server to hand out a specific DNS when assigning IP addresses to the network. This allows you to change every computer in one step, regardless of which system you are using.

    1. Nathon says:

      Yes, DHCP servers can do this. But how many people manage their own DHCP servers? I remember the first time I set one up and it took hours upon hours to figure out what I was doing.

    2. Nick Bell says:

      Server might not have been the best choice of words. You don’t need an actual server machine to do this. Your basic router (wireless or wired) acts as a DHCP server for your local network. Most tech people have one or more of these in their house. Setting it up to give you a specific DNS is generally an easy thing to do. For my router, it is no more difficult than setting the wireless password, as long as you have a specific DNS to set it to (such as Google’s linked above).

  2. Piflik says:

    I have sporadically the problem that my browser claims your site wouldn’t exist, but refreshing the site normally fixes the issue…don’t know what’s the problem, but I don’t think it has to do with my ISPs DNS server, because the site shouldn’t work at all then instead of the sporadic hiccups it has now…

    1. RJ says:

      I have had this same problem for a week or two.

    2. KremlinLaptop says:

      Third.

      1. Ross Bearman says:

        This is the problem I’ve been having with the site.

  3. Nathon says:

    I just got through moving my web site from a server at home to rapidxen. They do have handy CPU (and bandwidth and disk usage) graphs. I also still have the original server up for people whose DNS servers are sucky. I’ve been using OpenDNS for my nameservers since before Google entered the game and I’m pretty happy with them and their speed. So…if you can’t read this because your ISP’s DNS is terrible, switch to 208.67.222.222 and 208.67.222.220.

    So Shamus, did you not have the option of keeping your old server up while you complete the move?

    1. Shamus says:

      No, it was all done for me.

      1. Nathon says:

        Ah, the joys of managed hosting. What’s the matter, you don’t want to learn to be a good sysadmin on top of what you already do? It only takes a few person-years worth of reading manuals and you can save $2/month!

        1. Peter H. Coffin says:

          Saving $2/month is small, yes.

          The relief of knowing that if something is b0rk3d, you can fix it, even in the “eventually” timeframe, is priceless to nerds and control freaks.

      2. MichaelG says:

        Do I remember correctly that you were using Hosting Matters? That’s who I’m using, and their performance is frequently terrible. I open a connection to cPanel for my site, and it can take 45 seconds to respond.

        1. Shamus says:

          They used to be so awesome. I bounced around between hosts for a long time in the early 2000’s, and was overjoyed when HM offered solid hosting at a decent price.

          In the past 18 months things have gone poorly, and I’ve been slow to respond, remembering how bad other hosts were and what a monumental pain in the ass it is to move.

          1. Clint Olson says:

            For what it’s worth, I’ve been extremely happy with DreamHost. They give you unlimited disk space and bandwidth for a fairly low price, they’re big enough that their servers tend to be very solid, and they give you fairly low-level access for all your web-serving needs. They also have a great wiki that details how to do just about anything you want to do on their shared hosting.

          2. yd says:

            Moving shouldn’t be that hard, and could even be done relatively transparently to the users. You can set the new box up, dump the DB, re-import, set up a new DNS entry (www2.shamusyoung.com) to point to the new host for a while as well as switching http://www.shamusyoung.com over. You then put the old server on read-only (turn off comments, basically), and redirect anybody who hits the old one (due to stale DNS) to www2. for the time being.

            For what it’s worth, CPU usage is provided on a lot of hosting platforms, especially VPS providers. Linode, for example, graphs CPU, disk activity, bandwidth. VPS is a bit harder to work with (only a bit, if you use a decent distribution of Linux and keep up to date on security updates), but it gives you a lot more control.

            Given you’re having issues with your blog using resources, I don’t recommend Dreamhost, unlike Clint. They have scripts which kill anything using over certain amounts of CPU and tend to over-stuff their boxes. The customer service is excellent, but you get what you pay for in terms of resources. Disclaimer: I haven’t used their VPS offerings.

            * VPS being Virtual Private Server – a full OS just for you running through virtualization alongside other “virtual servers” on the same physical hardware.

            1. Heron says:

              I used 1&1 for a long time (they compete with DreamHost), but… to be brief, they have undocumented account limits that their first-level tech support is not aware of. That whole experience soured me on shared hosting providers, so perhaps I’m unfairly judging DreamHost, but there it is just the same. I did examine DreamHost briefly, but… I didn’t want to run into another random undocumented account limit. I’d rather manage a VPS myself so I know what I’m getting.

              You can actually do a server migration with only a few minutes of downtime and without redirects, if you’re willing to let the site run a little slower on the old server, and if your old web server can access your new database server.

              Disable comments on the old web server, then move the database to the new db server, point the old site at the new db server, and then re-enable comments. After that you can migrate the web server and DNS settings at your leisure, and your users won’t notice any downtime other than the brief time you’re copying the database. (That’s what I’m doing, anyway.)

              It’s even easier if you’re not changing database servers, in which case no downtime is necessary at all :)

              1. Ian says:

                I used 1&1 briefly and was put off by the 100MB database limit. I have a low traffic web forum and it was pushing 20MB. Even their developer accounts had the same limitation.

                They also refused to stop billing me after I discontinued their service. Luckily, I switched hosts right as my credit card was about to expire, so hah. I’m not the only person that this happened to, either. A client of mine used 1&1 and he’s still fighting with them about getting them to properly cancel his account.

                1. MrPyro says:

                  1&1 keep phoning me up to offer me free Exchange on the server we have with them. I have tried pointing out that the account in question belongs to a company that I haven’t worked for for three years, but that hasn’t stopped them yet.

                2. Heron says:

                  I wrote a… long rant about this two years ago. Make a sandwich and enjoy.

                3. Ian says:

                  @Heron: Yikes.

                  Well, that definitely makes me feel better about leaving them in the dust.

                  @MrPyro: Heh, yeah, I kept getting e-mails from them complaining about my domain name not having the “correct” (read: their) nameservers listed even after they stopped trying to charge my expired card. I don’t think they’re sending them anymore, but I’m not really sure. I just wound up flagging their mailings as spam and letting Gmail do the dirty work for me.

          3. SKD says:

            I can’t speak from experience but I have heard very good things about SquareSpace.com for hosting. Might be worth looking into if you start considering changing hosting providers.

            Disclaimer: I do not, nor have I ever worked for or used SquareSpace at the time of this posting.

          4. wootage says:

            It’s a wordpress blog, correct? Unless you’ve haxord core files, you should be able to just set up a new one, copy the theme folder and any other custom folders (uploads, etc.) over, do a DB export and import to the new site, change the DB logins in the WP config, and it should start working right there. I did that before on a local server setup, hopefully it’s the same for a production setup.

            However, you have to have the same domain name n’stuff, since WP puts that into key database entries during installation, and you’ll overwrite that when you do the import.

        2. Miral says:

          I use HM, and yes, the cPanel access speed is at times quite slow, but the site itself always seems to be pretty zippy. I’ve always assumed that they’re just prioritising “real” traffic over “admin” traffic.

          And they’ve got excellent tech support. Plus, I’ve been with them long enough now to get onto their infinite bandwidth plan (not that I need it).

  4. modus0 says:

    I experienced the site outages, but oddly only during the daytime and early evening periods.

    Really late at night I was able to connect to your site without problem, but any other time was a no go.

  5. TSED says:

    I have the weirdest problem of all. If I try to go to your site, I can’t. If I try to go to the comments of Spoiler Warning – Follow The Yellow Brick Railroad, I get in no problem, and from there can access anywhere else on the site no problem.

    But if I just go straight to shamusyoung.com/twentysidedtale, BLAMMO no-go; fail.

    Anyway, the ‘revelation’ that shaw is apparently cutting corners / not following proper DNS protocol / etc. comes about as much as a surprise to me as a multi-billion corporation investigation finding a corrupt businessman.

    Oh whoops, that analogy may have been a little too related to count as one…

    1. Simulated Knave says:

      Could be worse. It could be Rogers.

  6. Tometzky says:

    I think your DNS hosting provider is causing you strange DNS trouble:

    $ host -dr -t ns shamusyoung.com. a.gtld-servers.net.
    shamusyoung.com.	172800	IN	NS	ns3.hmdnsgroup.com.
    shamusyoung.com.	172800	IN	NS	ns4.hmdnsgroup.com.
    
    $ host -dr -t ns shamusyoung.com. ns3.hmdnsgroup.com.
    $ host -dr -t ns shamusyoung.com. ns4.hmdnsgroup.com.
    shamusyoung.com.	86400	IN	NS	ns5.hmdnsgroup.com.
    shamusyoung.com.	86400	IN	NS	ns6.hmdnsgroup.com.
    # It should be the same as above
    
    $ host -r -t ns shamusyoung.com. ns5.hmdnsgroup.com.
    $ host -r -t ns shamusyoung.com. ns6.hmdnsgroup.com.
    shamusyoung.com has no NS record
    # These should know shamusyoung.com
    
    $ host -r -t a www.shamusyoung.com. ns5.hmdnsgroup.com.
    $ host -r -t a www.shamusyoung.com. ns6.hmdnsgroup.com.
    # These should know www.shamusyoung.com also
    
    $ host -dr -t a www.shamusyoung.com. ns3.hmdnsgroup.com.
    $ host -dr -t a www.shamusyoung.com. ns4.hmdnsgroup.com.
    www.shamusyoung.com.	14400	IN	CNAME	shamusyoung.com.
    shamusyoung.com.	14400	IN	A	63.247.142.199
    # These reply correctly, but aren't authoritative

    I’m not sure why it sometimes works – it shouldn’t, this is a mess. Forward this to your domain hosting support – they should correct it.

    1. Bryan says:

      This is exactly what I found every time my local DNS server (which caches for the rest of the Internet, and provides authoritative records for my small internal network) started returning SERVFAIL responses.

      Lame servers (which is BIND’s term for this type of setup, where the authoritative DNS server for a domain claims it doesn’t have a clue about that domain) are generally a huge PITA, and are almost always caused by misconfiguration somewhere. In this case, it *looks* like the misconfiguration is not something you did, since it’s happening on the hmdnsgroup.com. nameservers, so yeah, definitely get in touch with them.

      The problem definitely seems to be the fact that ns{3,4} point at ns{5,6}. If they didn’t (if those two NS records got pointed back to them), I *suspect* everything would start working again once the 1-day TTLs expire.

    2. Sylvia says:

      Yep, this is your problem.

    3. Grag says:

      I was just thinking it might be something like that.

      And our local “crappy ISPs” dns probably have a limit on how long they cache results, and if the domain registrar doesn’t answer consistently about this domain, then periodically it will “fall off”.

      Of course, I’m a router/firewall dude, not a dns dude. I learned almost everything on the job where i’m working now( I still regularly school paid consultants)

    4. Tometzky says:

      I think your DNS hosting provider is causing you strange DNS trouble

      I see it is now corrected.

  7. eri says:

    I guess this means that Bell Canada aren’t just a bunch of greedy assholes with terrible customer service, high prices, traffic throttling, inexplicable outages and absurdly low bandwidth caps, they’re also lazy and don’t bother to update their DNS properly.

    On a note completely unrelated to ISPs, I really want to move to like, Norway or something right now.

    1. Mathias says:

      NORWAY?

      My pride as a citizen of the most insecure country in the world (Denmark, for those keeping tabs) refuses to let you travel to an inferior nation! All they have there is snow. And beer. And in certain northern regions, polar bears!

      No, move to Denmark. We have rolling restaurants, our bandwidth is the worst combination of cheap and crap, and our chief exports are beer and gravel. You will be hard-pressed to find a more boring civilized country than ours!

      -Hands travel brochure-

      1. TSED says:

        As a fellow Canadian, allow me to dispute your solicitations:

        1) Snow, beer, and polar bears? Did you not catch the “CANADA” part? Sounds like the biggest difference will be the english accents sounding awesome instead of sounding french.
        2) Norway’s national anthem is about 17x more awesome than yours. Sorry. (Farmers raise their axes, ho.)
        3) Norway’s metal scene is legendary. Your metal scene is…
        4) Denmark’s totes gonna flood.
        5) Norway doesn’t have tigers OR lions.

        1. eri says:

          Sometimes I wonder if it’d be worth moving to Scandinavia just for the music alone. At least Canada has a fairly vibrant scene, and a good number of legendary bands… *proudly wears his Gorguts hoodie*

          1. TSED says:

            And Cryptopsy. Though they’re an embarrassment now, just flash the “None So Vile” card and WHAMMO, you win.

            On the topic of music, I can’t believe how good Edmonton’s metal scene is. Begrime Exemious, Weapon, Quietus, blah blah blah? I rather expected it to be twelve kinds of awful.

        2. Mathias says:

          METAL?!

          WE DO NOT WANT YOU HERE! Norway can have you, we don’t need any more metalheads than we already have. Especially if you wear a T-shirt with an obscure bandname on. That is a license to be shot at dawn by a horde of angry fanboys in these parts of town.

          …And we have lions now? Cool. I guess we’ll lock it in with the moose Sweden sent us a few years ago.

          1. Chargone says:

            do you really still have that law about hitting swedes with sticks if they cross the ice rather than the bridge to get into Denmark in winter?

            cause that’s funny.

      2. krellen says:

        Sometimes when I’m feeling spiteful, I make plans to move to Finland and start referring to them all as Scandinavian.

        1. X2-Eliah says:

          Finland doesn’t count. Any Swede worth his weight in meatballs will tell you that.

          1. Rowan says:

            9 times out of ten you use “Fennoscandia” to refer to the Nordic countries and people go, huh? And you have to explain it.
            1 time out of ten you don’t bother with the “Fenno” bit and just say “Scandinavia” and there’s a singe geography smart-ass in the audience correcting you that Finland actually isn’t part of Scandinavia.

            1. X2-Eliah says:

              It’s a bit of a running joke, not being a smart-ass :P At least in Northern Sweden.

              Besides, I’m joking on the expense of Swedes as well here – seems a bit of a ridiculous gag to keep, but hey, when in Sweden…

            2. krellen says:

              In my experience, that smart-ass is usually a Finn.

        2. Sekundaari says:

          Why, you… you… wherever you are from, you!

          Seriously though, you’d just seem to be a foreigner who doesn’t know geography ’round here, nothing special. Even if you insisted on using “Scandinavian” after being corrected, I think you’d have to search long before you’d get any “Kyllä olis kirveellä tà¶itä” -reactions… I hope.

          1. Ingvar says:

            Minun motorisaha son saunasa!

          2. krellen says:

            In my youth, I spent a lot of time on MUDs – specifically MUDs hosted in Finland. I’ve gotten the reaction before, albeit in text form. It’s kind of funny how seriously it bothers your high school crowd (who were many of the players on said MUDs,) at least.

            This was like 20 years ago, though. Maybe Finns have loosened up?

            1. Sekundaari says:

              Maybe we have, or maybe they were going for geek cred. Maybe the high school students have the correct definition clear in their minds, and everyone else has forgotten it.

              Maybe you actually would get in trouble, it’s not like I’ve tried your trick. Anything’s possible.

      3. Mari says:

        Plus Denmark has the distinction of being the only Nazi-occupied nation to, as a large group, defend and protect their Jews. So that’s kind of cool. Apparently Danes have backbone. :-)

        1. Mathias says:

          No, we were just smart enough -not- to seem like we were fighting the nazis and then start doing it when they were drinking our tea and eating our biscuits. -Then- we rose up in armed (but mostly spiritual) warfare. We sent all the Jews in Denmark to Sweden, where they would be protected by diplomatic immunity.

          1. Mari says:

            But see, that alone shows backbone. While the Slovaks were offering to PAY to have their Jews deported to Germany and the French puppet-government was doing Germany’s bidding half-heartedly, you guys outfoxed the Fuhrer, getting the vast majority of your Jews to safety. I have a lot of admiration for smarts used well ;-)

        2. Soylent Dave says:

          I don’t know if that’s just backbone or ‘most countries in Europe didn’t really like Jews any more than the Reich did’.

          Hitler was notoriously astonished that Britain (for example) didn’t join the war on Germany’s side – the British Union of Fascists included some fairly high ranking politicians. At least until the Germans took it all a bit far in the 30s and we decided not to be anti-Semitic after all.

          It’s not really much of a surprise that Balkan and Baltic countries didn’t fight to protect their Jewish population – that was probably the only beneficial part of the occupation from their perspective.

      4. Nyaz says:

        Or you could move to Sweden, the most boring country in the world.
        Bandwidth costs pretty much nothing here, though.

        1. Mathias says:

          Damn Swedes. Don’t you take our most prestigeous title (most boring nation in the world) from us! WASN’T SKàÂĄNE ENOUGH FOR YOU?! (don’t worry if you don’t get it, it’s one of those sad continental in-jokes).

          1. Nyaz says:

            You can have SkàÂĄne back if you like…

        2. X2-Eliah says:

          It’s not so bad. All the benefits of Norway without the Fjords and the sights.

          1. krellen says:

            So what are the benefits of Norway if not the fjords and the sights?

    2. Blake says:

      Norway? More like SNOREWAY!

  8. LadyTL says:

    At least with Google Chrome, since their latest update alot of people have been having DNS problems. That was my problem that got fixed by manually changing to the google DNS servers.

    1. TSED says:

      I wonder if that’s what my problem is.

  9. Heron says:

    It could be worse, Shamus. Comcast has been intercepting my DNS traffic — I have my router set to use Google’s DNS servers, but Comcast has been answering my DNS queries. I get their universal typo squatting ad page DNS Helper search page if I try to go to a nonexistent domain. Their “tech support” guy didn’t understand what I was talking about, he just kept telling me to opt out of “DNS Helper” and I wouldn’t get the ads anymore.

    I guess I could do that, but that doesn’t solve the underlying problem — Comcast is intercepting DNS queries not directed at them, merely because the DNS query originated from inside their network.

    Oh well. At least they’re still obeying TTL rules.

    1. Nathaniel says:

      I ran into this myself. If you opt out of their “helpful” ads, they don’t redirect your DNS at all. I found this quite useful since their DNS servers used to go down for an hour once a week.

      1. Sumanai - a grouchy ball of cynical pessimism says:

        So, the penalty for not bringing them venue through watching ads is a better internet connection?

        1. Chargone says:

          they’re an American corporation.

          this is Good logic by that standard <_<

          1. Sumanai - a grouchy ball of cynical pessimism says:

            It’s Good Logic by the standard of “at least someone gains from it”, which seems to be as good as it gets for most companies, regardless of country.

  10. Raygereio says:

    Weird; I haven’t seen your site go down at all, Shamus and the last couple of days I’ve accessed this blog in the mornings, afternoons, etc. So not just one specific hour of day.

    Out of curiosity; any idea what can cause some people to get an error when trying to reach your site, and other people to be blissfully unaware of any technical issies? Lies the problem with the ISP, or something?

  11. Daemian Lucifer says:

    Weardest thing for me is that I was able to access your blog only half the time(from about 6ish gmt to about 18ish gmt).Personally,I like the explanation someone mentioned about net neutrality bitting you in the ass.

    1. Klay F. says:

      Its quite the comfortable society we have where pretty much the only downside (yes, I said THE ONLY downside, you don’t agree, tough) to net neutrality is convenience. I’m still convinced people aren’t smart enough to figure how screwed we will all be when it gets taken away by the inevitable world government.

      Then again, Anonymous will pretty much be screwed in every way possible when the world government takes over, so maybe its a worthy trade off.

  12. Sheer_Falacy says:

    I’ve seen it sometimes work and sometimes not, which would be pretty odd if it were an ISP DNS problem – I mean, once it was fixed it should have stayed fixed.

    1. Mari says:

      That’s my thing. I would be able to hit it, then 20 minutes later not be able to again. Then it would be back 14 hours later. Then gone again. If my ISP (which, arguably IS crappy) were at fault why was I only having problems with this one site and those problems were sporadic, randomly existing and then resolving?

      1. Chargone says:

        erratic/non-repeatable errors are a pain in any context…

  13. guy says:

    Incidentally, apparently IPv4 will run out of addresses by early march. That will be “fun”.

    1. eri says:

      Looks like another reason to upgrade to Windows 7, huh?

      1. SKD says:

        What does IPv4 have to do with Windows? XP supports IPv6.

        1. X2-Eliah says:

          I sincerely hope it’s not in the same way that “XP supports 64-bit”.. I mean, there is compatibility and there is claimed compatibility (and I don’t know which one in this case applies).

          1. Tobias says:

            No, it seems to be pretty alright. Incidentally, Windows is the only OS that has IPv6 privacy extensions enabled by default. WOOHOO, GO WINDOWS!

            I guess routers will be a lot more fun when ISPs let IPv6 kick in. There’s not a lot of them with IPv6 support built-in, and knowing hardware vendors, there won’t be a lot of firmware upgrades. To make matters worse, even the developers of the free DD-WRT firmware seem to think IPv6 is somehow unimportant.

            1. SKD says:

              That is probably because the majority keep poo-pooing it every time someone brings up the dwindling IPv4 addresses. Or coming up with things like NAT routing.

            2. X2-Eliah says:

              Damnit. Time to check my router’s spec-sheet.

  14. Joshua says:

    Yeah, the past few weeks I’ve had a lot of trouble. When I go to my bookmarks, this one IMMEDIATELY pulls up as invalid. I end up trying google to see if I can find my way into the site, and half of the posts end up with the same result.

  15. somebodys_kid says:

    I switched my router’s DNS servers to use google’s DNS and everything works beautifully now.

  16. Miral says:

    Regarding performance problems: I don’t recall the specifics, but I’m pretty sure there’s an option you can turn on in PHP or something which will give you the CPU rendering time of each request. Then you can log all of that somewhere and see if there are any trends. (Of course, it could be tricky to convince WordPress to let you make more fine-grained traces.)

  17. Josh Bray says:

    Oddly enough, yesterday I went to visit and still got nothing. I manually flushed my DNS cache in Windows and everything was peachy.

    TILL today, I visit your site again, and Chrome says “nobody home”.

    Switched over to Google Open DNS today, and it is all O.K.

    Rotten ISPs it MIGHT possibly be… or maybe you have a wonky DNS record at your host.

    Tomorrow I will switch myself back to the ISP DNS server and see if I get a “not home” error again. If this is still happening then, you might want to look at those DNS records and make sure no weird A or NS entries are there.

    I’ll let you know.

  18. Nick says:

    The DNS delay is not necessarily due to “rotten ISPs” it all depends on the tiers of the DNS servers and the TTL for caching.

    If there are 4 DNS servers between an ISP and a TLD DNS server and the TTL is set to 12 hours on all those servers, then it will take 4 x 12 = 48 hours for the IP change to propagate.

    1. Bryan says:

      No, it will only take 12h, because that’s not how caching works. Or, it’s not how caching is *supposed* to work, anyway.

      If a caching server writes an entry into its cache with a 4h TTL, it will *not* hand out that answer with a 12h TTL if it’s asked again (e.g. by some other client) in the future. Instead, it’ll subtract the amount of time that has passed since it got the 12h-TTL response itself, so that the end system is always expiring entries at the correct time.

      Yes, this does mean you can get a response with a 1-second TTL on it. (I don’t know if there are provisions for limiting the TTLs on the bottom end; there might be. An easy one would be to have the caching server expire the entry early, so it has to re-fetch before the end-time arrives.)

      Anyway, only *one* DNS server can be authoritative (well, one set of them: whatever set is in the NS record on the authoritative TLD server). All four DNS servers in your scenario *must* be caching.

      (Also, in Shamus’s setup, lots of caching servers — OpenDNS, Google Public DNS, maybe others — were working. So unless those servers are doing something weird with the cache, caching isn’t the problem. The lame server issue above seems to be to me, though I don’t know why some large caches are able to handle it. Maybe they ignore the redirect from ns{3,4} to ns{5,6} since ns{3,4} provide the correct data.)

  19. Jep jep says:

    Couldn’t get to the site for almost a week with regular DNS. Used OpenDNS to get around it. Now it seems to be working fine. All I can say it seems ridiculously widespread.

    (Here when I thought my ISP would be up to bar with this sort of stuff, but who knows..)

  20. General Karthos says:

    My problem is different. I can’t get to the site between the hours of approximately 10:00 A.M. and 2:00 P.M. Pacific Time. All other times work just fine. But every single day, for weeks, I have not been able to reach the site at those times. I have no idea why that should be, nor does anyone else. I have to wonder if it has something to do with my school’s connection. I mean, our wireless internet is laden with problems… I’m fairly sure that a large portion of our routers run on coal.

  21. Graham says:

    Yeah, having managed multiple WordPress sites on shared hosting, it is a huge CPU hog. Supercache is the first plugin I install, and it has saved my hosting many many times.

  22. Falling says:

    Yay, it’s back! I couldn’t get in for quite a few days.

  23. Simplex says:

    I live in Poland, for a few days Shamus blog was not working for me. But what puzzles me is this:
    I went to dns/ip resolver thingy and typed “www.shamusyoung.com” into the box and I supposedly got back the IP address associated with the domain – 63.247.142.199

    So this should allow me to access shamus blog despite the DNS fail, right?

    Um, actually, no. When I typed this address I got some kind of Apache template:

    http://63.247.142.199/cgi-sys/defaultwebpage.cgi

    Why this happened? This is to the contrary of what shamus wrote in this post (yellow box).

    1. Bryan says:

      Because (I’m assuming) lots of other DNS names map to the same IP. It’s all done using name-based virtual hosting (assuming Apache; other web servers call it something different). The server looks up the Host: header that the browser sent, and serves up a different site depending on the hostname it sees. When you try to browse to the IP address, the browser sends that IP address in the Host: header.

      What this *does* mean is that you can point http://www.shamusyoung.com to that IP address in your hosts file, thereby ignoring DNS entirely, and the browser should still send the proper string as the Host: header. Didn’t think of that earlier; hmm…

  24. Simon says:

    Adding another ISP to the tally:

    Telia, semi-state owned and Sweden’s largest phone and internet provider, and a Tier 1 carrier!
    Didn’t fetch the new IP until just now, so it took them almost a week!

    1. Nyaz says:

      Yep, Telia here too. Haven’t seen this site in quite a few days up until like, yesterday.

  25. Arkady says:

    Shamus wrote:

    “I'm sure you've noticed that my site tends to go down a lot.”

    Maybe it just met the internet server version of Lord Flashheart?

  26. Shadow says:

    Well, at least it’s back up again.

    I was almost temped to bug Shamus on Steam…

  27. Dev Null says:

    Seriously? They managed a move for you from one server to another, and they didn’t drop the TTL on your address to 5 minutes at least 24 hours in advance? They have done this whole web hosting thing before, right?

  28. wootage says:

    I apparently have had the least trouble reaching the site. I use OpenDNS free, and once in recent history your site was unavailable for a bit.

    I keep wondering why in god’s name hosting companies don’t set up so they can just reassign your old IP to your new machine and cut all the DNS crapola out of the loop. What the DNS server does not know will not hurt it (or you).

    1. Bryan says:

      Because lots of stuff is virtual hosted. If they moved by IP, they’d be moving hundreds of sites at a time. :-)

  29. somecrazyfan says:

    You know, Shamus, with you being such a busy person, answering to your post seems futile.
    Some people’s comments become lost in the sea of comments and there is a homogenity among the answers to your post. People with a different opinion can’t make themselves heard by you and for them you mean at least something more than the other bloggers. It is hard to find a blog that has interesting AND long posts AND that are related to video games. And I don’t mean people that are for/against the stream, saying things like “OMG this popular game sucks/it’s superb”.
    I want game analysis, and the opinion of a programmer/video gamer about “how things were done in a game” and “how could they have been improved”.
    And you gave us that.Now we have 2 let’s plays, a video one that I don’t like, a mmo one that I enjoy, but doesn’t come out often enough. And a lot of things that I don’t want to see.
    Why did you give up of the older Shamus? Where’s the level design analysis from Thief, the character analysis from Jade Empire, the analysis of the story in Indigo Prophecy?The analysis of DIAS and similar design choices and of the escort AI?

    1. rofltehcat says:

      I also enjoyed a lot of the old stuff more than the new stuff. This doesn’t mean that I don’t enjoy the new stuff but I just found the old stuff to have more variety and be a bit more entertaining.

      I guess it is the series. While I like the idea behind Spoiler Warning, it gets a bit boring after 20 or so episodes. I was actually hoping for a greater selection of games when you switched formats from 40 to 15 minutes, spending less time with each game. I like Mass Effect 2 but it is just soooo loooong.

      I understand that some of the ‘old stuff’ required a lot of research. Analysing something is probably a lot more work than some other projects and as we all know your request to whoever created the universe to give your day more hours doesn’t seem to have been answered yet ;(

      But I guess you’ll never satisfy all the people on teh_internetz anyways. I still enjoy reading your blog, even if I tend to spend a little less time here than I sometimes used to. You’re still doing an amazing job and I guess we should be happy that you supply us with this large amount of high quality content. Thank you, Shamus :)

      1. Klay F. says:

        I’m not going to bother looking, but I’m sure people called Shamus a sell-out when he started to make posts about things other than his D&D games. What people don’t really understand is he is an actual human being whose interests fluctuate (like all of us). I do not operate under the assumption that Shamus has a responsibility to provide us with content. There is only so much he can say about any singular topic before its just beating a dead horse (except for DRM rants, obviously).

  30. Neal White says:

    I support multiple clients with various local and national ISP’s. It wasn’t that long ago that I had 3 clients – one on Charter, one on Quest and one on a local called Rapid Web. Each one had trouble finding some web sites, but in every case the other two ISP’s could resolve the DNS to the site that the third could not find.
    I ended up converting ALL of my clients to 4.2.2.2 for their primary DNS and it worked fine. Each client could find all their needed web sites and all were happy. Until this year when that DNS server was taken off-line.
    Ouch!

  31. Antwon says:

    I dunno whether the fix was “AT&T finally got off their ass and updated DNS records” or “Shamus busted some heads so that the DNS resolution would propagate more smoothly”… but in any event: I can see this website from home again! For the first time in days upon days! Huzzah! I’m ever-so-pleased.

  32. Newbie says:

    The last sentence wasn’t right I think we should see more of it… the site that is…

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