The sys admin's daily grind: Dnstop

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Article from Issue 185/2016
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In last month's issue, Charly sent the lean pdnsd DNS cache down the catwalk. To see whether pdnsd really does the work expected of it, he now puts dnstop through infinite rounds in the name of names.

Most distributions include dnstop. If you prefer to build it yourself, you will find the source code online [1], but make sure you download and build the matching Libpcap [2] first. I launched the tool on the computer hosting my DNS cache with the following command:

dnstop -l 3 eth0

The -l 3 parameter tells dnstop to explore name requests up to the third level. For a request like www.linux-magazine.com, com is the first or top-level domain, linux-magazine is thus the second-level domain, and www is the third level.

[...]

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