systemd-resolved

SYSTEMD-RESOLVED.SERVICE(8)systemd-resolved.serviceSYSTEMD-RESOLVED.SERVICE(8)

NAME
       systemd-resolved.service, systemd-resolved - Network Name Resolution
       manager

SYNOPSIS
       systemd-resolved.service

       /lib/systemd/systemd-resolved

DESCRIPTION
       systemd-resolved is a system service that provides network name
       resolution to local applications. It implements a caching and
       validating DNS/DNSSEC stub resolver, as well as an LLMNR resolver and
       responder. In addition it maintains the
       /run/systemd/resolve/resolv.conf file for compatibility with
       traditional Linux programs. This file may be symlinked from
       /etc/resolv.conf.

       The glibc NSS module nss-resolve(8) is required to permit glibc's NSS
       resolver functions to resolve host names via systemd-resolved.

       The DNS servers contacted are determined from the global settings in
       /etc/systemd/resolved.conf, the per-link static settings in
       /etc/systemd/network/*.network files, and the per-link dynamic settings
       received over DHCP. See resolved.conf(5) and systemd.network(5) for
       details. To improve compatibility, /etc/resolv.conf is read in order to
       discover configured system DNS servers, but only if it is not a symlink
       to /run/systemd/resolve/resolv.conf (see above).

       systemd-resolved synthesizes DNS RRs for the following cases:

       o   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).

       o   The hostname "localhost" (as well as any hostname ending in
           ".localhost", ".localdomain" or equal to "localdomain") is resolved
           to the IP addresses 127.0.0.1 and ::1.

       o   The hostname "gateway" 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.

       o   The mappings defined in /etc/hosts are resolved to their configured
           addresses and back.

       Lookup requests are routed to the available DNS servers and LLMNR
       interfaces according to the following rules:

       o   Lookups for the special hostname "localhost" are never routed to
           the network. (A few other, special domains are handled the same
           way.)

       o   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 "gateway" host name are never routed to LLMNR.

       o   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 address range are
           never routed to DNS.

       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.

       Routing of lookups may be influenced by configuring per-interface
       domain names. See systemd.network(5) for details. Lookups for a
       hostname ending in one of the per-interface domains are exclusively
       routed to the matching interfaces.

       Note that /run/systemd/resolve/resolv.conf should not be used directly
       by applications, but only through a symlink from /etc/resolv.conf.

       See the resolved D-Bus API Documentation[1] for information about the
       APIs systemd-resolved provides.

SEE ALSO
       systemd(1), resolved.conf(5), dnssec-trust-anchors.d(5), nss-
       resolve(8), systemd-resolve(1), resolv.conf(5), hosts(5),
       systemd.network(5), systemd-networkd.service(8)

NOTES
        1. resolved D-Bus API Documentation
           http://www.freedesktop.org/wiki/Software/systemd/resolved

systemd 229                                        SYSTEMD-RESOLVED.SERVICE(8)
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