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man: document resolved's RR synthesizing and query routing

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Lennart Poettering 2015-08-26 10:30:06 +02:00
parent da1d9fc2cc
commit 2dc6b11d29

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<?xml version='1.0'?> <!--*-nxml-*-->
<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
@ -71,6 +71,61 @@
<citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for more details.</para>
<para><command>systemd-resolved</command> synthesizes DNS RRs for the following cases:</para>
<itemizedlist>
<listitem><para>The local, configured hostname is resolved to
all locally configured IP addresses ordered by their scope, or
— if none are configured — the IPv4 address 127.0.0.2 (which
is on the local loopback) and the IPv6 address ::1 (which is the
local host).</para></listitem>
<listitem><para>The hostname <literal>localhost</literal> is
resolved to the IP addresses 127.0.0.1 and
::1.</para></listitem>
<listitem><para>The hostname <literal>gateway</literal> is
resolved to all current default routing gateway addresses,
ordered by their metric. This assigns a stable hostname to the
current gateway, useful for referencing it independently of the
current network configuration state.</para></listitem>
</itemizedlist>
<para>Lookup requests are routed to the available DNS servers
and LLMNR interfaces according to the following rules:</para>
<itemizedlist>
<listitem><para>Lookups for the special hostname
<literal>localhost</literal> are never routed to the
network.</para></listitem>
<listitem><para>Single-label names are routed to all local
interfaces capable of IP multicasting, using the LLMNR
protocol. Lookups for IPv4 addresses are only sent via LLMNR on
IPv4, and lookups for IPv6 addresses are only sent via LLMNR on
IPv6. Lookups for the locally configured host name and the
<literal>gateway</literal> host name are never routed to
LLMNR.</para></listitem>
<listitem><para>Multi-label names are routed to all local
interfaces that have a DNS sever configured, plus the globally
configured DNS server if there is one. Address lookups from the
link-local addres range are never routed to
DNS.</para></listitem>
</itemizedlist>
<para>If lookups are routed to multiple interfaces, the first
successful response is returned (thus effectively merging the
lookup zones on all matching interfaces). If the lookup failed on
all interfaces the last failing response is returned.</para>
<para>Routing of lookups may be influenced by configuring
per-interface domain names, see
<citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for details. Lookups for a hostname ending in one of the
per-interface domains are exclusively routed to the matching
interfaces.</para>
<para>Note that
<filename>/run/systemd/resolve/resolv.conf</filename> should not
be used directly, but only through a symlink from