ISProblems
May 22, 2013 10:31 AM Subscribe
What is it with CenturyLink, and some ISP in Hong Kong whose name I forget, that every so often it will decide that it can't "find" a web page... usually one that I was just at, and often including metafilter! Instead of going to the page I want, it redirects me to a CenturyLink search page, like this, which has the link I want at the very top (www.metafilter.com in this example), yet when I click on that link from their completely extraneous search page, it just goes back to the same search page?!
I am travelling, and this is not my home ISP. I am using Firefox, with NoScript. But I only have this problem with certain ISPs (namely, CentruyLink, and whatever it was in Hong Kong).
I am travelling, and this is not my home ISP. I am using Firefox, with NoScript. But I only have this problem with certain ISPs (namely, CentruyLink, and whatever it was in Hong Kong).
Best answer: "- Can I opt out of this service?
Yes, you can opt out of this service at any time. If you choose to opt-out, this preference will be stored permanently and apply to all computers connecting to the Internet via your CenturyLink connection. To disable or enable the service you must be on a computer connected to your CenturyLink modem. You may disable it by clicking here."
(From the FAQ linked in the page you included as an example)
posted by caution live frogs at 11:06 AM on May 22, 2013 [1 favorite]
Yes, you can opt out of this service at any time. If you choose to opt-out, this preference will be stored permanently and apply to all computers connecting to the Internet via your CenturyLink connection. To disable or enable the service you must be on a computer connected to your CenturyLink modem. You may disable it by clicking here."
(From the FAQ linked in the page you included as an example)
posted by caution live frogs at 11:06 AM on May 22, 2013 [1 favorite]
Response by poster: But I guess the larger question is, why does CenturyLink randomly choose to forget the address for www.metafilter.com?
posted by eviemath at 11:11 AM on May 22, 2013
posted by eviemath at 11:11 AM on May 22, 2013
The ad revenue from that search page probably doesn't provide a lot of incentive for maximizing their nameserver uptime.
posted by ceribus peribus at 11:45 AM on May 22, 2013
posted by ceribus peribus at 11:45 AM on May 22, 2013
More than likely their nameserver isn't responsive or kind of sucks and times out when attempting to look up a domain.
posted by mikeh at 12:10 PM on May 22, 2013
posted by mikeh at 12:10 PM on May 22, 2013
Response by poster: I was thinking it would be a time-out on their DNS servers as well, but the bizarre part is that it won't find that domain's address again during the same session - I have to disconnect and wait a bit and then reconnect to the local internet (eg. reboot my computer); or sometimes wait a long enough time, but I haven't carefully measured how long is sufficient yet. It won't even go "back" to a page in the www.metafilter.com domain that I was previously on, when this occurs. In other words, it seems to store the information that it can't find an address to associate with the domain; but doesn't store the information that it has already found the address for that domain. And further, this information is linked just to the IP address that it assigns my computer, and gets deleted when their servers release the IP address when I've logged off of the network? Maybe the redirect to the search results page is implemented poorly - like, it just gets set as a redirect for the rest of my session - and now that I have that turned off, it will actually try to search for the address for the domain name again each time.
posted by eviemath at 12:33 PM on May 22, 2013
posted by eviemath at 12:33 PM on May 22, 2013
Try switching your nameserver to the free google one. I had trouble for a while with my ISP's nameservers and that fixed it. If this was just a rare intermittent issue it might be not worth doing, but if it is that annoying, switching is likely to fix it.
posted by jclarkin at 12:51 PM on May 22, 2013
posted by jclarkin at 12:51 PM on May 22, 2013
Response by poster: Thanks everyone! In terms of the answer to my question "why does this happen", I'm increasingly thinking that it's a problem with how CenturyLink set up the redirect to their search page. Only looking for additional answers now if they can clarify this question.
posted by eviemath at 1:22 PM on May 22, 2013
posted by eviemath at 1:22 PM on May 22, 2013
If you really want to try to get more technical information, you need to run the right tools to see what is going on. The program "nslookup" is where I would start.
For example, from the command prompt of windows 7 I get this:
>nslookup metafilter.com
Server: xxxxxxxxxxxxxx
Address: 10.65.116.29
Non-authoritative answer:
Name: metafilter.com
Address: 50.22.177.14
I xxxxx'ed out my server name, you will get whatever one you are using. If it fails, it will tell you.
You can use -debug (or -d2) on the command line to get more information on the windows 7 version. Linux, Unix, MacOS, etc all have versions of this program.
DNS is one of the major pieces of the internet that many people don't think about until it doesn't work. It's very likely your ISP just isn't doing a good job and their server is lousy.
posted by jclarkin at 2:46 PM on May 22, 2013
For example, from the command prompt of windows 7 I get this:
>nslookup metafilter.com
Server: xxxxxxxxxxxxxx
Address: 10.65.116.29
Non-authoritative answer:
Name: metafilter.com
Address: 50.22.177.14
I xxxxx'ed out my server name, you will get whatever one you are using. If it fails, it will tell you.
You can use -debug (or -d2) on the command line to get more information on the windows 7 version. Linux, Unix, MacOS, etc all have versions of this program.
DNS is one of the major pieces of the internet that many people don't think about until it doesn't work. It's very likely your ISP just isn't doing a good job and their server is lousy.
posted by jclarkin at 2:46 PM on May 22, 2013
Response by poster: Let me clarify: the phenomenon that baffled me was not so much that CenturyLink's DNS servers were slow or inadequate to handle the traffic they experience and/or periodically failing. It was that I would get redirected to the search page - and then never be able to get back to another page on the same domain in that internet session. Switching off the search option as caution live frogs suggested seems to have fixed this behavior.
posted by eviemath at 9:23 AM on May 23, 2013
posted by eviemath at 9:23 AM on May 23, 2013
The problem most likely has to do with DNS caching. Every DNS response you get has a TTL value (Time To Live) which tells your computer, and any intermediate DNS servers which might be caching responses, how long they can keep a copy of that response before they need to go ask for it again. (This means that instead of sending out a new DNS query for metafilter.com every time you click on a new link, your computer can remember the IP address it got last time.)
If the nameserver you're using can't resolve a name to an IP address, it's supposed to send back an error message so that your computer knows it failed, and it can try the query again next time you try to go to that site. However, what some ISPs have done is changed the configuration of their nameservers so that for any failed query, they return the IP of an ad-farming server owned by the ISP, so they can serve you ads. This is evil and breaks the internet, but it's also potentially quite profitable.
The result is that you ask CenturyLink's DNS for the IP address of metafilter.com, and if it fails then it just sends you back an (apparently successful) response with the IP of CenturyLink's ad-farming server instead. And that response probably has a nice long TTL (let's say, 1800 seconds), which it absolutely should not. And so, for the next 30 minutes, whenever you try to go to a page on metafilter.com, your computer asks itself "Do I need to look up metafilter.com?" And then it answers, "No I don't, because I've got a cached response that hasn't expired yet, and it says the IP of metafilter.com is (IP address of CenturyLink ad server). So I'll just go there instead of trying to look it up again." Of course, if you disconnect from CenturyLink and connect again, your local DNS cache will get cleared, so the next time you try to go to metafilter.com, your computer will send another query and hopefully get a proper response.
I second using Google's free DNS (8.8.8.8 and 8.8.4.4) as your DNS servers to bypass this sort of idiocy. Of course, some ISPs may block DNS queries sent outside of their own network, precisely to force you into playing along with their nasty little advertising scheme.
posted by McCoy Pauley at 6:50 PM on May 25, 2013 [2 favorites]
If the nameserver you're using can't resolve a name to an IP address, it's supposed to send back an error message so that your computer knows it failed, and it can try the query again next time you try to go to that site. However, what some ISPs have done is changed the configuration of their nameservers so that for any failed query, they return the IP of an ad-farming server owned by the ISP, so they can serve you ads. This is evil and breaks the internet, but it's also potentially quite profitable.
The result is that you ask CenturyLink's DNS for the IP address of metafilter.com, and if it fails then it just sends you back an (apparently successful) response with the IP of CenturyLink's ad-farming server instead. And that response probably has a nice long TTL (let's say, 1800 seconds), which it absolutely should not. And so, for the next 30 minutes, whenever you try to go to a page on metafilter.com, your computer asks itself "Do I need to look up metafilter.com?" And then it answers, "No I don't, because I've got a cached response that hasn't expired yet, and it says the IP of metafilter.com is (IP address of CenturyLink ad server). So I'll just go there instead of trying to look it up again." Of course, if you disconnect from CenturyLink and connect again, your local DNS cache will get cleared, so the next time you try to go to metafilter.com, your computer will send another query and hopefully get a proper response.
I second using Google's free DNS (8.8.8.8 and 8.8.4.4) as your DNS servers to bypass this sort of idiocy. Of course, some ISPs may block DNS queries sent outside of their own network, precisely to force you into playing along with their nasty little advertising scheme.
posted by McCoy Pauley at 6:50 PM on May 25, 2013 [2 favorites]
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If this process fails you should be notified. Many ISPs appear to use this as an opportunity to advertise and present a "search page" that presents ads and possible alternatives to what they think failed.
If you click the correct link, you should get the correct page. But if the correct name failed to get an address once, it may again. It seems likely that it is an intermittent problem with your ISPs nameserver.
If this really bothers you, you can choose another nameserver. Google runs a public one.
posted by jclarkin at 10:46 AM on May 22, 2013 [1 favorite]