103 lines
6.5 KiB
HTML
103 lines
6.5 KiB
HTML
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<!DOCTYPE html
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<meta name="DC.Title" content="Understanding zones" />
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<meta name="abstract" content="This topic explains Domain Name System (DNS) zones and zone types." />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Understanding zones</title>
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</head>
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<body id="rzakkconceptbasic"><a name="rzakkconceptbasic"><!-- --></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">Understanding zones</h1>
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<div><p>This topic explains Domain Name System (DNS) zones and zone types.</p>
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<div class="section"><p>DNS data is divided into manageable sets of data called <em>zones</em>.
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Zones contain name and IP address information about one or more parts of a
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DNS domain. A server that contains all of the information for a zone is the
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authoritative server for the domain. Sometimes it makes sense to delegate
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the authority for answering DNS queries for a particular subdomain to another
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DNS server. In this case, the DNS server for the domain can be configured
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to refer the subdomain queries to the appropriate server.</p>
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<p>For backup
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and redundancy, zone data is often stored on servers other than the authoritative
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DNS server. These other servers are called secondary servers, which load zone
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data from the authoritative server. Configuring secondary servers allows you
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to balance the demand on servers and also provides a backup in case the primary
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server goes down. Secondary servers obtain zone data by doing zone transfers
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from the authoritative server. When a secondary server is initialized, it
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loads a complete copy of the zone data from the primary server. The secondary
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server also reloads zone data from the primary server or from other secondaries
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for that domain when zone data changes.</p>
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</div>
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<div class="section"><h4 class="sectiontitle">DNS zone types</h4><p>You can use iSeries™ DNS to define several types of
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zones to help you manage DNS data:</p>
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<dl><dt class="dlterm">Primary zone</dt>
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<dd>Primary zone loads zone data directly from a file on a host. It can contain
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a subzone, or child zone. It can also contain resource records, such as host,
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alias (CNAME), address (A), or reverse mapping pointer (PTR) records.<div class="note"><span class="notetitle">Note:</span> Primary
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zones are sometimes referred to as <em>master zones</em> in other BIND documentation.</div>
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<dl><dt class="dlterm">Subzone</dt>
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<dd>A subzone defines a zone within the primary zone. Subzones allow you to
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organize zone data into manageable pieces.<dl><dt class="dlterm">Child zone</dt>
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<dd>A child zone defines a subzone and delegates responsibility for the subzone
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data to one or more name servers.</dd>
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<dt class="dlterm">Alias (CNAME)</dt>
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<dd>An alias defines an alternate name for a primary domain name.</dd>
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<dt class="dlterm">Host</dt>
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<dd>A host object maps A and PTR records to a host. Additional resource records
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can be associated with a host.</dd>
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</dl>
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</dd>
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</dl>
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</dd>
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</dl>
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<dl><dt class="dlterm">Secondary zone</dt>
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<dd>Secondary zone loads zone data from a zone's primary server or another
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secondary server. It maintains a complete copy of the zone for which it is
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a secondary.<dl><dt class="dlterm">Stub zone</dt>
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<dd>A stub zone is similar to a secondary zone, but it only transfers the
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name server (NS) records for that zone.</dd>
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<dt class="dlterm">Forward zone</dt>
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<dd>A forward zone directs all queries for that particular zone to other servers.</dd>
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</dl>
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</dd>
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</dl>
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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="rzakkconceptparent.htm" title="This topic explains what Domain Name System (DNS) is and how it works. It also shows the different types of zones that can be defined on a DNS server.">Domain Name System concepts</a></div>
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</div>
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<div class="relconcepts"><strong>Related concepts</strong><br />
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<div><a href="rzakkconceptquery.htm" title="This topic explains how Domain Name System (DNS) resolves queries on behalf of clients.">Understanding Domain Name System queries</a></div>
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<div><a href="rzakkconfignamesrvrzone.htm" title="After you configure a Domain Name System (DNS) server instance, you need to configure the zones for the name server.">Configure zones on a name server</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="rzakkscenario1.htm" title="This example depicts a simple subnet with a Domain Name System (DNS) server for internal use.">Example: Single Domain Name System server for an intranet</a></div>
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<div><a href="rzakkconceptresourcerec.htm" title="This topic explains how resource records are used by Domain Name System (DNS). Resource records are used to store data about domain names and IP addresses. This topic contains a searchable list of resource records supported for OS/400 V5R1.">Domain Name System resource records</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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