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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>2. Guardian</title><link rel="stylesheet" href="docbook.css" type="text/css" /><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="PowerDNS manual" /><link rel="up" href="pdns-internals.html" title="Appendix B. PDNS internals" /><link rel="prev" href="pdns-internals.html" title="Appendix B. PDNS internals" /><link rel="next" href="modules.html" title="3. Modules & Backends" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">2. Guardian</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="pdns-internals.html">Prev</a> </td><th width="60%" align="center">Appendix B. PDNS internals</th><td width="20%" align="right"> <a accesskey="n" href="modules.html">Next</a></td></tr></table><hr /></div><div class="sect1" title="2. Guardian"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="guardian"></a>2. Guardian</h2></div></div></div><p>
When launched by the init.d script, <code class="filename">pdns_server</code> wraps itself inside a 'guardian'. This guardian monitors the
performance of the inner <code class="filename">pdns_server</code> instance which shows up in the process list of your OS as
<code class="filename">pdns_server-instance</code>.
It is also this guardian that <code class="filename">pdns_control</code> talks to. A <span class="command"><strong>STOP</strong></span> is interpreted by the guardian,
which causes the guardian to sever the connection to the inner process and terminate it, after which it terminates itself.
The init.d script <span class="command"><strong>DUMP</strong></span> and <span class="command"><strong>SHOW</strong></span> commands need to access the inner process, because
the guardian itself does not run a nameserver. For this purpose, the guardian passes controlsocket requests to the control console of the
inner process. This is the same console as seen with init.d <span class="command"><strong>MONITOR</strong></span>.
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