59 lines
3.8 KiB
HTML
59 lines
3.8 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="security" content="public" />
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<meta name="Robots" content="index,follow" />
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<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
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<meta name="DC.Type" content="reference" />
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<meta name="DC.Title" content="Data caching" />
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<meta name="abstract" content="Data caching of responses to Domain Name System (DNS) queries is done by i5/OS sockets in an effort to lessen the amount of network traffic. The cache is added to and updated as needed." />
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<meta name="description" content="Data caching of responses to Domain Name System (DNS) queries is done by i5/OS sockets in an effort to lessen the amount of network traffic. The cache is added to and updated as needed." />
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<meta name="DC.Relation" scheme="URI" content="dns.htm" />
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<meta name="DC.Relation" scheme="URI" content="xdns.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2001, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2001, 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="datac" />
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<meta name="DC.Language" content="en-us" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Data caching</title>
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</head>
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<body id="datac"><a name="datac"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Data caching</h1>
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<div><p>Data caching of responses to Domain Name System (DNS)
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queries is done by i5/OS™ sockets in an effort to lessen the amount of
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network traffic. The cache is added to and updated as needed.</p>
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<div class="section"><p>If RES_AAONLY (authoritative answers only) is set in _res.options,
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the query is always sent on the network. In this case, the cache is never
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checked for the answer. If RES_AAONLY is not set, the cache is checked for
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an answer to the query before any attempt to send it on the network is performed.
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If the answer is found and the time to live has not expired, the answer is
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returned to the user as the answer to the query. If the time to live has expired,
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the entry is removed, and the query is sent on the network. Also, if the answer
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is not found in the cache, the query is sent on the network. </p>
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</div>
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<div class="section"><p>Answers from the network are cached if the responses are authoritative.
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Non-authoritative answers are not cached. Also, responses received as a result
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of an inverse query are not cached. You can clear this cache by updating the
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DNS configuration with either the CHGTCPDMN, CFGTCP option 12, or through iSeries™ Navigator.</p>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="dns.htm" title="iSeries provides applications with access to the Domain Name System (DNS) through the resolver functions.">Domain Name System support</a></div>
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</div>
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<div class="relref"><strong>Related reference</strong><br />
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<div><a href="xdns.htm" title="This example shows how to query and update Domain Name System (DNS) records.">Example: Update and query DNS</a></div>
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</div>
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</div>
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</body>
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</html>
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