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DNS caching. Questions also answers

Many users probably faced with such a situation, at which time suddenly the proportion of sites ceases to be revealed, or is revealed very slowly. One of the common reasons for this is a slow or idle DNS server at the provider. In this article we will solve this problem, but at the same time help save a little traffic.

So, we need to set up our own caching DNS server, which one will turn to various DNS servers, including the root ones. An obvious task begins: however, why not just once to register the main DNS servers in the TCP / IP properties of the connection? The answers are as follows: they usually respond several times slower than the provider's DNS server — also for someone the exchange traffic with them is more expensive than the exchange traffic with the local server.

Before the source of work, we download the list of Internet DNS servers first (this is a simple text file, which you can rename to named_root.txt also open in a text editor). Then we download the caching DNS server ExtraDNS.

Run the installer, install, reboot. Then he will say something about ExtraDNS.dll - click "Ok". Is done. Immediately put the checkbox on the "Startup in system tray", so that after the download program was minimized to the system tray. Now you need to register in the settings DNS-servers. Moving to the "Server" tab.

By default, it shows some terribly slow foreign servers that are allowed to boldly boldly. To find out which DNS server will be the most urgent for us, click the "Test" button.

In the field "Nameservers" enter the IP address of the DNS server, which must be checked for speed, also click "Start!" From the results we are interested in Ping time. We write out the tested IP addresses also the value of Ping time. We repeat testing of all servers from the named.root file also indicated by your provider. Done, close the test window.

Now we select those servers that most quickly responded from the compiled list, and we also add them to ExtraDNS. Servers are polled from top to bottom, so in the first line we indicate the fastest DNS server (usually the one that your provider advises is the fastest), then the slower ones. Now ExtraDNS will turn to the main server, but if it is temporarily unavailable or could not answer at all, then the next one in the list is also so on. Complete the entire list is optional - enough for 4-5 pieces.

Now it is necessary to indicate to the Windows operating system that we have our own DNS server. We make our way into the properties of the connection with the provider, select "Use the following DNS server addresses" and also enter the main server

Everything, now we will use our DNS server also does not depend on the provider DNS.

For example, in a week up to 96% of DNS calls from the ExtraDNS cache, the total saving of pores was about 13 minutes. In addition, at least to the gaze, it may seem insignificant to save a few milliseconds each time the site is accessed, but think about it: the browser, when loading web pages that contain a lot of links to graphics, also banners, has to once again have queries to DNS. And when working, for example, through GPRS, the overall very significant acceleration will also result in traffic savings.