systemd-resolve Man page

SYSTEMD-RESOLVE(1) systemd-resolve SYSTEMD-RESOLVE(1)

NAME

systemd-resolve – Resolve domain names, IPV4 and IPv6 addresses, DNS
resource records, and services

SYNOPSIS

systemd-resolve [OPTIONS…] HOSTNAME…

systemd-resolve [OPTIONS…] ADDRESS…

systemd-resolve [OPTIONS…] –type=TYPE RRDOMAIN…

systemd-resolve [OPTIONS…] –service [[NAME] TYPE] DOMAIN

systemd-resolve [OPTIONS…] –statistics

systemd-resolve [OPTIONS…] –reset-statistics

DESCRIPTION

systemd-resolve may be used to resolve domain names, IPv4 and IPv6
addresses, DNS resource records and services with the systemd-
resolved.service(8) resolver service. By default, the specified list of
parameters will be resolved as hostnames, retrieving their IPv4 and
IPv6 addresses. If the parameters specified are formatted as IPv4 or
IPv6 operation the reverse operation is done, and a hostname is
retrieved for the specified addresses.

The –type= switch may be used to specify a DNS resource record type
(A, AAAA, SOA, MX, …) in order to request a specific DNS resource
record, instead of the address or reverse address lookups. The special
value “help” may be used to list known values.

The –service switch may be used to resolve SRV[1] and DNS-SD[2] services (see below). In this mode, between one and three arguments are
required. If three parameters are passed the first is assumed to be the
DNS-SD service name, the second the SRV service type, and the third the
domain to search in. In this case a full DNS-SD style SRV and TXT
lookup is executed. If only two parameters are specified, the first is
assumed to be the SRV service type, and the second the domain to look
in. In this case no TXT RR is requested. Finally, if only one parameter
is specified, it is assumed to be a domain name, that is already
prefixed with an SRV type, and an SRV lookup is done (no TXT).

The –statistics switch may be used to show resolver statistics,
including information about the number of succesful and failed DNSSEC
validations.

The –reset-statistics may be used to reset various statistics counters
maintained the resolver, including those shown in the –statistics
output. This operation requires root privileges.

OPTIONS

-4, -6
By default, when resolving a hostname, both IPv4 and IPv6 addresses
are acquired. By specifying -4 only IPv4 addresses are requested,
by specifying -6 only IPv6 addresses are requested.

-i INTERFACE, –interface=INTERFACE
Specifies the network interface to execute the query on. This may
either be specified as numeric interface index or as network
interface string (e.g. “en0”). Note that this option has no effect
if system-wide DNS configuration (as configured in /etc/resolv.conf
or /etc/systemd/resolve.conf) in place of per-link configuration is
used.

-p PROTOCOL, –protocol=PROTOCOL
Specifies the network protocol for the query. May be one of “dns”
(i.e. classic unicast DNS), “llmnr” (Link-Local Multicast Name
Resolution[3]), “llmr-ipv4”, “llmnr-ipv6” (LLMNR via the indicated
underlying IP protocols). By default the lookup is done via all
protocols suitable for the lookup. If used, limits the set of
protocols that may be used. Use this option multiple times to
enable resolving via multiple protocols at the same time. The
setting “llmnr” is identical to specifying this switch once with
“llmnr-ipv4” and once via “llmnr-ipv6”. Note that this option does
not force the service to resolve the operation with the specified
protocol, as that might require a suitable network interface and
configuration. The special value “help” may be used to list known
values.

-t TYPE, –type=TYPE, -c CLASS, –class=CLASS
Specifies the DNS resource record type (e.g. A, AAAA, MX, …) and
class (e.g. IN, ANY, …) to look up. If these options are used a
DNS resource record set matching the specified class and type is
requested. The class defaults to IN if only a type is specified.
The special value “help” may be used to list known values.

–service
Enables service resolution. This enables DNS-SD and simple SRV
service resolution, depending on the specified list of parameters
(see above).

–service-address=BOOL
Takes a boolean parameter. If true (the default), when doing a
service lookup with –service the hostnames contained in the SRV
resource records are resolved as well.

–service-txt=BOOL
Takes a boolean parameter. If true (the default), when doing a
DNS-SD service lookup with –service the TXT service metadata
record is resolved as well.

–cname=BOOL
Takes a boolean parameter. If true (the default), DNS CNAME or
DNAME redirections are followed. Otherwise, if a CNAME or D

NAME

record is encountered while resolving, an error is returned.

–search=BOOL
Takes a boolean parameter. If true (the default), any specified
single-label hostnames will be searched in the domains configured
in the search domain list, if it is non-empty. Otherwise, the
search domain logic is disabled.

–legend=BOOL
Takes a boolean parameter. If true (the default), column headers
and meta information about the query response are shown. Otherwise,
this output is suppressed.

–statistics
If specified general resolver statistics are shown, including
information whether DNSSEC is enabled and available, as well as
resolution and validation statistics.

–reset-statistics
Resets the statistics counters shown in –statistics to zero.

-h, –help
Print a short help text and exit.

–version
Print a short version string and exit.

EXAMPLES
Example 1. Retrieve the addresses of the “www.0pointer.net” domain

$ systemd-resolve www.0pointer.net

Example 2. Retrieve the domain of the “85.214.157.71” IP address

$ systemd-resolve 85.214.157.71

Example 3. Retrieve the MX record of the “0pointer.net” domain

$ systemd-resolve -t MX 0pointer.net

Example 4. Resolve an SRV service

$ systemd-resolve –service _xmpp-server._tcp gmail.com

SEE ALSO

systemd, systemd-resolved.service(8)

NOTES
1. SRV
https://tools.ietf.org/html/rfc2782

2. DNS-SD
https://tools.ietf.org/html/rfc6763

3. Link-Local Multicast Name Resolution
https://tools.ietf.org/html/rfc4795

systemd 229 SYSTEMD-RESOLVE(1)