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    <title>s6-dns: the s6-dnsip6 program</title>
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<p>
<a href="index.html">s6-dns</a><br />
<a href="http://skarnet.org/software/">Software</a><br />
<a href="http://skarnet.org/">skarnet.org</a>
</p>

<h1> The s6-dnsip6 program </h1>

<p>
  s6-dnsip6 finds the IPv6 addresses associated to a domain name.
</p>

<h2> Interface </h2>

<pre>
     s6-dnsip6 [ -q ] [ -r ] [ -t <em>timeout</em> ] <em>domain</em>
</pre>

<ul>
 <li> s6-dnsip6 makes an AAAA query for the name <em>domain</em>. It
waits for the result and prints the obtained IPv6 addresses, one per line,
then exits 0. </li>
 <li> If the domain exists but no relevant field has been found, it exits 1. </li>
 <li> If the DNS answered but no answer is available, it prints a relevant
error message and exits 2. </li>
 <li> By default, s6-dnsip6 looks for DNS cache addresses in the
<tt>/etc/resolv.conf</tt> file. If the DNSCACHEIP environment variable is set
and contains a list of IP (v4 or v6) addresses, separated by commas,
semicolons, spaces, tabs, newlines or carriage returns, then this list
is used instead. </li>
</ul>

<h2> Options </h2>

<ul>
 <li> <tt>-q</tt>&nbsp;: qualify. Qualifies <em>domain</em> before resolution,
according to suffixes found in <tt>/etc/resolv.conf</tt>. If the DNSQUALIFY
environment variable is set and contains a list of suffixes separated by spaces,
tabs, newlines or carriage returns, then this list is used instead. By
default, no qualification is used: if <em>domain</em> is not a FQDN, a dot
is just appended to it. </li>
 <li> <tt>-r</tt>&nbsp;: random. By default, the program does not sort the
result, but prints them in the order received from the DNS. With this
option, it performs a random permutation on the results before printing
them. </li>
 <li> <tt>-t</tt>&nbsp;<em>timeout</em>&nbsp;: if the resolution takes more
than <em>timeout</em> milliseconds, then it exits 99 right away with an error
message. By default, <em>timeout</em> is 0, which means no timeout. </li>
</ul>

<h2> Notes </h2>

<p>
 Bear in mind that <em>making AAAA queries</em> is very different, and
totally independent, from <em>using IPv6 transport for the DNS queries</em>.
Even if the underlying skalibs has been compiled without IPv6 support,
or IPv6 DNS transport is unavailable for any reason, you can still perform
AAAA queries and s6-dnsip6 will answer correctly.
</p>

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