unbound - Unbound DNS validating resolver 1.9.2.
unbound [-h] [-d] [-p] [-v] [-c
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 continue until
an answer is found or no answer is available (NXDOMAIN). For performance and
efficiency reasons that answer is cached for a certain 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 DNSSEC validation.
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:
unbound.conf(5), unbound-checkconf(8), nsd(8).
Unbound developers are mentioned in the CREDITS file in the distribution.
- Show the version and commandline option help.
- -c cfgfile
- Set the config file with settings for unbound to read instead of reading
the file at the default location, /var/unbound/etc/unbound.conf. The
syntax is described in unbound.conf(5).
- 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.
- 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
- Increase verbosity. If given multiple times, more information is logged.
This is in addition to the verbosity (if any) from the config file.