• What to do if some sites do not open (server not found)

    When I was in Vietnam, I noticed that some sites do not open when the Internet is working normally. For example, twitter and facebook are cool enough sites to get over the idea that sites just hang.

    When trying to access the site, the browser immediately gave an error "Server not found", without even trying to "get through". It is immediately obvious that there are some problems with DNS routing. Oh, sorry, I forgot that I am writing an article for those who want to understand, and not for those who already understand.

    So, I will try to explain the essence of the problem in a simple and accessible way and offer its solution. As a bonus, this solution will help protect you from malicious sites, and your children's computers from adult sites.

    If some sites do not open for you (the server was not found), but you were able to open this article, then you still have access to the Internet. The problem of accessibility of some sites may come from your network equipment (for example, a WiFi router) or even from your carrier.

    Diagnostics

    But first you need to find out if the site is really not available only to you, or if it is not available to everyone at the moment. I know a couple of services for this. First: (viewing HTTP headers). The link will open a page with an empty field URL. I enter twitter.com into it (you write the name of the site you are checking) and click "Check". The rest of the fields do not need to be touched. If the site is working, I see:

    The main thing is that the response should contain the green line HTTP/1.1 200 OK - immediately or after other lines. This means that the site is receiving visitors. And here is an example of the case when the site does not work:

    I use another service for the performance of my sites: (monitoring the availability of sites):

    We find this form at the top of the site and enter the site address. After a few seconds, we get the result in the form of a table:

    The table will be large, but the verdict is already visible in the title: 1 Fail, 38 Ok - this means that out of 38 monitoring points (in different cities and countries of the World), the site is available, and from one it is not available. If the vast majority of points give the result “Ok”, then everything is fine with the site. And if about 10 or more dots return a “Fail” response, then the site is unstable or unavailable at all. Unfortunately, the host-tracker.com service itself is sometimes unavailable due to high load.

    Solution

    Of course, we will only decide the issue of the inaccessibility of the site just for you. If the site is not available to everyone, then you need to contact the hosting provider, if the site is yours, or postpone visiting the site.

    A good solution, as I found out for myself - using alternative DNS(you don't even need to know to use them). As soon as I realized that I needed alternative DNS, I easily found several authoritative addresses, from which I chose .

    The link contains information for configuring your routers, computers with different operating systems, even tablets and smartphones on Yandex.DNS (a great way to restrict your children's access to malicious and adult sites). Of course, it's all free and doesn't require any software to be installed. It is only necessary to register DNS addresses in the network settings. For example, I will describe my case of setting up Windows 8.1 (if I'm not mistaken, everything is the same or very similar in Windows 7 and XP):

    Added. Google also has DNS. To make it work for sure, one of the DNS servers (preferred or alternative) can be set to Yandex, and the other to Google. For example, like this:

    • 77.88.8.88
    • 8.8.8.8

    And today DNS from Yandex did not give me access to Google services until I specified the DNS servers as shown in the example above.

    We re-diagnose and enjoy. In my settings, I used DNS addresses that do not provide access to fraudulent and infected sites. Of course, sites are blocked only if Yandex has revealed the bad intentions of the site owners. So, this is not a reason to get rid of your antivirus.

    Similarly, you can configure "Basic" DNS (access to all sites) or "Family" (with protection from adult sites) - the difference is only in the last number of the address. The setup described in this article in some cases really helps to make Internet access more stable and faster, as well as solve the problem of inaccessibility of some sites.

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