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DNS caching. Questions and answers

Many users probably faced such a situation, at what time suddenly the share of sites ceases to open, or opens very slowly. One of the most common reasons for this is a slow or idle DNS server from the provider. In this article we will solve this problem, but at the same time we will help to save a little traffic.

So, we need to set up our own caching DNS server, which will personally access various DNS servers, including root servers. The obvious task begins: however, why not just 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 ISP's DNS server, and for others, traffic with them is more expensive than traffic to the local server.

Prior to the source of work, the list is downloaded first DNS-servers of the Internet (this is a simple text file, which it is allowed to 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 - press "Ok". Done. Immediately put the daw on the "Startup in system tray", so that later the program is minimized to the system tray. Now you need to set up DNS servers in the settings. Move to the "Server" tab.

By default, it lists some terribly slow foreign servers that are allowed to boldly delete. To find out which DNS server is the fastest for us, we press the "Test" button.

In the "Nameservers" field, enter the IP address of the DNS server, which you need to check for speed, also click "Start!" From the results we are interested in Ping time. Write out the tested IP-addresses also the value of Ping time. Repeat testing of all servers from the file named.root also specified by your ISP. Done, close the test window.

Now we select from the list of those servers that most hastily responded also make them into ExtraDNS. Servers are polled in the order from top to bottom, so in the first line, specify the fastest DNS server (usually the fastest one is the one advised by your provider), then slower. Now ExtraDNS will address to the main server, but if it is temporarily unavailable or could not respond in any way, then to the next one on the list also. The entire list is optional - enough 4-5 pieces.

Now you need to tell the Windows operating system that we have to use our DNS server. We make our way to connection properties with the provider, choose "Use the following DNS server addresses" also enter the main server 127.0.0.1.

Everything, now we will use our DNS-server also not to depend on provider DNS.

To the sample, I had up to 96% of calls to DNS over the week, from the cache of ExtraDNS, and the total saving of pores was about 13 minutes. In addition, although the main eye may seem insignificant saving a few milliseconds every time you access the site, but, think: the browser when loading web pages that contain many references to the graphics also banners, you have to once again apply for DNS queries. And with labor, for example, through GPRS will become a general very significant acceleration and also traffic saving.