The sys admin's daily grind – Pdnsd

Short-Term Memory

Article from Issue 184/2016
Author(s):

Cache it, if you can! When the latencies of his Internet connection seem to take longer than Napoleon's reign, sys admin Charly comes up with a solution for name resolution.

It is always annoying when I need to use Internet via a satellite route. The latency is really bad. To counteract this, I use caching wherever I can. My choice of cache for DNS requests is Pdnsd [1]. More or less any fat distribution will have the lean and fast daemon in its collection. When launched, the daemon parses the content of /etc/hosts and stores it in its cache. Any DNS requests that I make are added.

By default, the cache is 2MB. If you have built a very long /etc/hosts throughout your IT landscape, you can modify the cache size in /etc/pdnsd.conf. The matching option resides in the global section. It goes by the name of perm_cache and expects the size in bytes – I use 8192. By the way, the option is named perm_cache because the cache not only resides in RAM but also on the disk. In other words, Pdnsd does not need to build the cache from scratch after a reboot.

In the global configuration section, you will find other central settings. One setting that is very important is:

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