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unbound(8) unbound 1.16.3 unbound(8)
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unbound - Unbound DNS validating resolver 1.16.3.
unbound [-h] [-d] [-p] [-v] [-c cfgfile]
Unbound is a caching DNS resolver.
It uses a built in list of authoritative nameservers for the root zone
(.), the so called root hints. On receiving a DNS query it will ask
the root nameservers for an answer and will in almost all cases receive
a delegation to a top level domain (TLD) authoritative nameserver. It
will then ask that nameserver for an answer. It will recursively con-
tinue until an answer is found or no answer is available (NXDOMAIN).
For performance and efficiency reasons that answer is cached for a cer-
tain time (the answer's time-to-live or TTL). A second query for the
same name will then be answered from the cache. Unbound can also do
To use a locally running Unbound for resolving put
If authoritative DNS is needed as well using nsd(8), careful setup is
required because authoritative nameservers and resolvers are using the
same port number (53).
The available options are:
-h Show the version number and commandline option help, and exit.
Set the config file with settings for Unbound to read instead of
reading the file at the default location,
/etc/unbound/unbound.conf. The syntax is described in
-d Debug flag: do not fork into the background, but stay attached
to the console. This flag will also delay writing to the log
file until the thread-spawn time, so that most config and setup
errors appear on stderr. If given twice or more, logging does
not switch to the log file or to syslog, but the log messages
are printed to stderr all the time.
-p Don't use a pidfile. This argument should only be used by
supervision systems which can ensure that only one instance of
Unbound will run concurrently.
-v Increase verbosity. If given multiple times, more information is
logged. This is added to the verbosity (if any) from the config
-V Show the version number and build options, and exit.
unbound.conf(5), unbound-checkconf(8), nsd(8).
Unbound developers are mentioned in the CREDITS file in the distribu-
NLnet Labs Sep 21, 2022 unbound(8)