104 lines
6.6 KiB
HTML
104 lines
6.6 KiB
HTML
<?xml version="1.0" encoding="UTF-8"?>
|
|
<!DOCTYPE html
|
|
PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
|
<html lang="en-us" xml:lang="en-us">
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
|
<meta name="security" content="public" />
|
|
<meta name="Robots" content="index,follow" />
|
|
<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))' />
|
|
<meta name="DC.Type" content="concept" />
|
|
<meta name="DC.Title" content="Problem: DNS records are not being updated by DHCP" />
|
|
<meta name="abstract" content="The iSeries DHCP server is capable of dynamically updating DNS resource records. Dynamic update errors might be caused by the failure of DNS records update." />
|
|
<meta name="description" content="The iSeries DHCP server is capable of dynamically updating DNS resource records. Dynamic update errors might be caused by the failure of DNS records update." />
|
|
<meta name="DC.Relation" scheme="URI" content="rzakgtroubleshooting.htm" />
|
|
<meta name="DC.Relation" scheme="URI" content="rzakgconceptddns.htm" />
|
|
<meta name="copyright" content="(C) Copyright IBM Corporation 2004, 2006" />
|
|
<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2004, 2006" />
|
|
<meta name="DC.Format" content="XHTML" />
|
|
<meta name="DC.Identifier" content="rzakgproblemddns" />
|
|
<meta name="DC.Language" content="en-us" />
|
|
<!-- All rights reserved. Licensed Materials Property of IBM -->
|
|
<!-- US Government Users Restricted Rights -->
|
|
<!-- Use, duplication or disclosure restricted by -->
|
|
<!-- GSA ADP Schedule Contract with IBM Corp. -->
|
|
<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
|
|
<link rel="stylesheet" type="text/css" href="./ic.css" />
|
|
<title>Problem: DNS records are not being updated by DHCP</title>
|
|
</head>
|
|
<body id="rzakgproblemddns"><a name="rzakgproblemddns"><!-- --></a>
|
|
<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
|
|
<h1 class="topictitle1">Problem: DNS records are not being updated by DHCP</h1>
|
|
<div><p>The iSeries™ DHCP
|
|
server is capable of dynamically updating DNS resource records. Dynamic update
|
|
errors might be caused by the failure of DNS records update.</p>
|
|
<p>Refer to <a href="rzakgconceptddns.htm#rzakgconceptddns">Dynamic updates</a> for
|
|
details about this capability. The DHCP server uses name resolution functions
|
|
and programming interfaces to determine the appropriate dynamic DNS server
|
|
to update. You can use this to your advantage when determining the source
|
|
of dynamic update errors.</p>
|
|
<p>Check the following points when the DNS records are not
|
|
being updated dynamically.</p>
|
|
<dl><dt class="dlterm">Verify which subnets and the type of resource records (A and/or PTR records)
|
|
are being updated.</dt>
|
|
<dd> Check the DHCP configuration and verify that the client's subnet is set
|
|
up to dynamically update resource records and which type of record is being
|
|
updated.</dd>
|
|
</dl>
|
|
<dl><dt class="dlterm">Verify that i5/OS™ Option 31 (Domain Name System) is
|
|
installed on the iSeries server
|
|
that is running DHCP.</dt>
|
|
<dd>The DHCP server uses programming interfaces provided by i5/OS Option
|
|
31. The DNS that is being dynamically updated does not need to reside on the
|
|
same iSeries server
|
|
as the DHCP server.</dd>
|
|
</dl>
|
|
<dl><dt class="dlterm">Verify the DHCP server is authorized to send updates to the DNS server.</dt>
|
|
<dd>Check the DNS configuration to verify the DNS zone is configured to allow
|
|
dynamic updates and that the DHCP server is included in the Access Control
|
|
List.</dd>
|
|
</dl>
|
|
<dl><dt class="dlterm">Verify that the DNS servers can resolve the client's domain.</dt>
|
|
<dd>Display the list of DNS servers on the iSeries server where DHCP resides using
|
|
the CHGTCPDMN command. Verify that these DNS servers can resolve the domain
|
|
that is being updated. To do this, run NSLOOKUP from the iSeries server
|
|
where DHCP is running to resolve a name (or IP address) that exists in the
|
|
domain that is failing to be updated. The DHCP server must be able to derive
|
|
the fully qualified domain name (FQDN) of the client to update its DNS record.
|
|
The DHCP server will not attempt to update a dynamic DNS without a FQDN (the
|
|
host name and domain name of the client). The DHCP server derives the FQDN
|
|
of the client using the following sequence:<ol><li>Option 81 (Client FQDN) in the DHCPREQUEST message from the client.</li>
|
|
<li>Option 12 (Host Name) and/or Option 15 (Domain Name) in the DHCPREQUEST
|
|
message from the client.</li>
|
|
<li>Option 12 (Host Name) in the DHCPREQUEST message from the client and/or
|
|
Option 15 (Domain Name) configured in the DHCP server. In this case, to derive
|
|
the FQDN, the DHCP server must be configured to append the domain name to
|
|
the host name (specified on the <span class="menucascade"><span class="uicontrol">Properties</span> > <span class="uicontrol">Dynamic DNS</span></span> tab for the global level,
|
|
subnet, class, or client).</li>
|
|
</ol>
|
|
</dd>
|
|
</dl>
|
|
<dl><dt class="dlterm">The TXT record might not match the corresponding DNS record.</dt>
|
|
<dd>The DHCP server can be configured to check the existing DNS resource records
|
|
to determine which DHCP client they are associated with. The DHCP server accomplishes
|
|
this by writing a corresponding TXT record with each A and PTR record that
|
|
it updates in the DNS. If the server is configured to verify the client ID
|
|
before performing the DNS update, then the TXT record data must match the
|
|
client ID of the client that received the address from the DHCP server. If
|
|
it does not match, the DHCP server will not update the DNS A resource record.
|
|
This is done to prevent overwriting existing records. However, the DHCP server
|
|
can be configured to ignore the existing records and perform DNS updates regardless
|
|
of the data in the TXT record (specified on the <span class="menucascade"><span class="uicontrol">Properties</span> > <span class="uicontrol">Dynamic DNS</span></span> tab for the global level,
|
|
subnet, class, or client).</dd>
|
|
</dl>
|
|
</div>
|
|
<div>
|
|
<div class="familylinks">
|
|
<div class="parentlink"><strong>Parent topic:</strong> <a href="rzakgtroubleshooting.htm" title="You can view job log and trace data, as well as use troubleshooting lists for common problems.">Troubleshoot DHCP</a></div>
|
|
</div>
|
|
<div class="relconcepts"><strong>Related concepts</strong><br />
|
|
<div><a href="rzakgconceptddns.htm" title="You can use your DHCP server in conjunction with your DNS server to dynamically update the client information in the DNS when DHCP assigns the client an IP address.">Dynamic updates</a></div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html> |