dig - DNS lookup utility
dig [@server] [-b address] [-c class] [-f filename] [-k filename] [-m] [-p port#] [-q name] [-t type] [-v] [-x addr] [-y [hmac:]name:key] [ [-4] | [-6] ] [name] [type] [class] [queryopt...] dig [-h] dig [global-queryopt...] [query...]
DIG(1) BIND 9 DIG(1)
NAME
dig - DNS lookup utility
SYNOPSIS
dig [@server] [-b address] [-c class] [-f filename] [-k filename] [-m]
[-p port#] [-q name] [-t type] [-v] [-x addr] [-y [hmac:]name:key] [
[-4] | [-6] ] [name] [type] [class] [queryopt...]
dig [-h]
dig [global-queryopt...] [query...]
DESCRIPTION
dig is a flexible tool for interrogating DNS name servers. It performs
DNS lookups and displays the answers that are returned from the name
server(s) that were queried. Most DNS administrators use dig to trou-
bleshoot DNS problems because of its flexibility, ease of use, and
clarity of output. Other lookup tools tend to have less functionality
than dig.
Although dig is normally used with command-line arguments, it also has
a batch mode of operation for reading lookup requests from a file. A
brief summary of its command-line arguments and options is printed when
the -h option is given. The BIND 9 implementation of dig allows multi-
ple lookups to be issued from the command line.
Unless it is told to query a specific name server, dig tries each of
the servers listed in /etc/resolv.conf. If no usable server addresses
are found, dig sends the query to the local host.
When no command-line arguments or options are given, dig performs an NS
query for "." (the root).
It is possible to set per-user defaults for dig via ${HOME}/.digrc.
This file is read and any options in it are applied before the com-
mand-line arguments. The -r option disables this feature, for scripts
that need predictable behavior.
The IN and CH class names overlap with the IN and CH top-level domain
names. Either use the -t and -c options to specify the type and class,
use the -q to specify the domain name, or use "IN." and "CH." when
looking up these top-level domains.
SIMPLE USAGE
A typical invocation of dig looks like:
dig @server name type
where:
server is the name or IP address of the name server to query. This can
be an IPv4 address in dotted-decimal notation or an IPv6 address
in colon-delimited notation. When the supplied server argument
is a hostname, dig resolves that name before querying that name
server.
If no server argument is provided, dig consults
/etc/resolv.conf; if an address is found there, it queries the
name server at that address. If either of the -4 or -6 options
are in use, then only addresses for the corresponding transport
are tried. If no usable addresses are found, dig sends the query
to the local host. The reply from the name server that responds
is displayed.
name is the name of the resource record that is to be looked up.
type indicates what type of query is required - ANY, A, MX, SIG, etc.
type can be any valid query type. If no type argument is sup-
plied, dig performs a lookup for an A record.
OPTIONS
-4 This option indicates that only IPv4 should be used.
-6 This option indicates that only IPv6 should be used.
-b address[#port]
This option sets the source IP address of the query. The address
must be a valid address on one of the host's network interfaces,
or "0.0.0.0" or "::". An optional port may be specified by
appending #port.
-c class
This option sets the query class. The default class is IN; other
classes are HS for Hesiod records or CH for Chaosnet records.
-f file
This option sets batch mode, in which dig reads a list of lookup
requests to process from the given file. Each line in the file
should be organized in the same way it would be presented as a
query to dig using the command-line interface.
-k keyfile
This option tells named to sign queries using TSIG using a key
read from the given file. Key files can be generated using
tsig-keygen. When using TSIG authentication with dig, the name
server that is queried needs to know the key and algorithm that
is being used. In BIND, this is done by providing appropriate
key and server statements in named.conf.
-m This option enables memory usage debugging.
-p port
This option sends the query to a non-standard port on the
server, instead of the default port 53. This option is used to
test a name server that has been configured to listen for
queries on a non-standard port number.
-q name
This option specifies the domain name to query. This is useful
to distinguish the name from other arguments.
-r This option indicates that options from ${HOME}/.digrc should
not be read. This is useful for scripts that need predictable
behavior.
-t type
This option indicates the resource record type to query, which
can be any valid query type. If it is a resource record type
supported in BIND 9, it can be given by the type mnemonic (such
as NS or AAAA). The default query type is A, unless the -x
option is supplied to indicate a reverse lookup. A zone transfer
can be requested by specifying a type of AXFR. When an incremen-
tal zone transfer (IXFR) is required, set the type to ixfr=N.
The incremental zone transfer contains all changes made to the
zone since the serial number in the zone's SOA record was N.
All resource record types can be expressed as TYPEnn, where nn
is the number of the type. If the resource record type is not
supported in BIND 9, the result is displayed as described in RFC
3597.
-u This option indicates that print query times should be provided
in microseconds instead of milliseconds.
-v This option prints the version number and exits.
-x addr
This option sets simplified reverse lookups, for mapping
addresses to names. The addr is an IPv4 address in dotted-deci-
mal notation, or a colon-delimited IPv6 address. When the -x
option is used, there is no need to provide the name, class, and
type arguments. dig automatically performs a lookup for a name
like 94.2.0.192.in-addr.arpa and sets the query type and class
to PTR and IN respectively. IPv6 addresses are looked up using
nibble format under the IP6.ARPA domain.
-y [hmac:]keyname:secret
This option signs queries using TSIG with the given authentica-
tion key. keyname is the name of the key, and secret is the
base64-encoded shared secret. hmac is the name of the key algo-
rithm; valid choices are hmac-md5, hmac-sha1, hmac-sha224,
hmac-sha256, hmac-sha384, or hmac-sha512. If hmac is not speci-
fied, the default is hmac-md5; if MD5 was disabled, the default
is hmac-sha256.
NOTE:
Only the -k option should be used, rather than the -y option,
because with -y the shared secret is supplied as a command-line
argument in clear text. This may be visible in the output from ps1
or in a history file maintained by the user's shell.
QUERY OPTIONS
dig provides a number of query options which affect the way in which
lookups are made and the results displayed. Some of these set or reset
flag bits in the query header, some determine which sections of the
answer get printed, and others determine the timeout and retry strate-
gies.
Each query option is identified by a keyword preceded by a plus sign
(+). Some keywords set or reset an option; these may be preceded by the
string no to negate the meaning of that keyword. Other keywords assign
values to options, like the timeout interval. They have the form +key-
word=value. Keywords may be abbreviated, provided the abbreviation is
unambiguous; for example, +cd is equivalent to +cdflag. The query
options are:
+[no]aaflag
This option is a synonym for +[no]aaonly.
+[no]aaonly
This option sets the aa flag in the query.
+[no]additional
This option displays [or does not display] the additional sec-
tion of a reply. The default is to display it.
+[no]adflag
This option sets [or does not set] the AD (authentic data) bit
in the query. This requests the server to return whether all of
the answer and authority sections have been validated as secure,
according to the security policy of the server. AD=1 indicates
that all records have been validated as secure and the answer is
not from a OPT-OUT range. AD=0 indicates that some part of the
answer was insecure or not validated. This bit is set by
default.
+[no]all
This option sets or clears all display flags.
+[no]answer
This option displays [or does not display] the answer section of
a reply. The default is to display it.
+[no]authority
This option displays [or does not display] the authority section
of a reply. The default is to display it.
+[no]badcookie
This option retries the lookup with a new server cookie if a
BADCOOKIE response is received.
+[no]besteffort
This option attempts to display the contents of messages which
are malformed. The default is to not display malformed answers.
+bufsize[=B]
This option sets the UDP message buffer size advertised using
EDNS0 to B bytes. The maximum and minimum sizes of this buffer
are 65535 and 0, respectively. +bufsize=0 disables EDNS (use
+bufsize=0 +edns to send an EDNS message with an advertised size
of 0 bytes). +bufsize restores the default buffer size.
+[no]cdflag
This option sets [or does not set] the CD (checking disabled)
bit in the query. This requests the server to not perform DNSSEC
validation of responses.
+[no]class
This option displays [or does not display] the CLASS when print-
ing the record.
+[no]cmd
This option toggles the printing of the initial comment in the
output, identifying the version of dig and the query options
that have been applied. This option always has a global effect;
it cannot be set globally and then overridden on a per-lookup
basis. The default is to print this comment.
+[no]comments
This option toggles the display of some comment lines in the
output, with information about the packet header and OPT pseudo-
section, and the names of the response section. The default is
to print these comments.
Other types of comments in the output are not affected by this
option, but can be controlled using other command-line switches.
These include +[no]cmd, +[no]question, +[no]stats, and
+[no]rrcomments.
+[no]cookie=####
This option sends [or does not send] a COOKIE EDNS option, with
an optional value. Replaying a COOKIE from a previous response
allows the server to identify a previous client. The default is
+cookie.
+cookie is also set when +trace is set to better emulate the
default queries from a nameserver.
+[no]crypto
This option toggles the display of cryptographic fields in
DNSSEC records. The contents of these fields are unnecessary for
debugging most DNSSEC validation failures and removing them
makes it easier to see the common failures. The default is to
display the fields. When omitted, they are replaced by the
string [omitted] or, in the DNSKEY case, the key ID is displayed
as the replacement, e.g. [ key id = value ].
+[no]defname
This option, which is deprecated, is treated as a synonym for
+[no]search.
+[no]dnssec
This option requests that DNSSEC records be sent by setting the
DNSSEC OK (DO) bit in the OPT record in the additional section
of the query.
+domain=somename
This option sets the search list to contain the single domain
somename, as if specified in a domain directive in
/etc/resolv.conf, and enables search list processing as if the
+search option were given.
+dscp=value
This option sets the DSCP code point to be used when sending the
query. Valid DSCP code points are in the range [0...63]. By
default no code point is explicitly set.
+[no]edns[=#]
This option specifies the EDNS version to query with. Valid val-
ues are 0 to 255. Setting the EDNS version causes an EDNS query
to be sent. +noedns clears the remembered EDNS version. EDNS is
set to 0 by default.
+[no]ednsflags[=#]
This option sets the must-be-zero EDNS flags bits (Z bits) to
the specified value. Decimal, hex, and octal encodings are
accepted. Setting a named flag (e.g., DO) is silently ignored.
By default, no Z bits are set.
+[no]ednsnegotiation
This option enables/disables EDNS version negotiation. By
default, EDNS version negotiation is enabled.
+[no]ednsopt[=code[:value]]
This option specifies the EDNS option with code point code and
an optional payload of value as a hexadecimal string. code can
be either an EDNS option name (for example, NSID or ECS) or an
arbitrary numeric value. +noednsopt clears the EDNS options to
be sent.
+[no]expire
This option sends an EDNS Expire option.
+[no]fail
This option indicates that named should try [or not try] the
next server if a SERVFAIL is received. The default is to not try
the next server, which is the reverse of normal stub resolver
behavior.
+[no]header-only
This option sends a query with a DNS header without a question
section. The default is to add a question section. The query
type and query name are ignored when this is set.
+[no]identify
This option shows [or does not show] the IP address and port
number that supplied the answer, when the +short option is
enabled. If short form answers are requested, the default is not
to show the source address and port number of the server that
provided the answer.
+[no]idnin
This option processes [or does not process] IDN domain names on
input. This requires IDN SUPPORT to have been enabled at compile
time.
The default is to process IDN input when standard output is a
tty. The IDN processing on input is disabled when dig output is
redirected to files, pipes, and other non-tty file descriptors.
+[no]idnout
This option converts [or does not convert] puny code on output.
This requires IDN SUPPORT to have been enabled at compile time.
The default is to process puny code on output when standard out-
put is a tty. The puny code processing on output is disabled
when dig output is redirected to files, pipes, and other non-tty
file descriptors.
+[no]ignore
This option ignores [or does not ignore] truncation in UDP
responses instead of retrying with TCP. By default, TCP retries
are performed.
+[no]keepalive
This option sends [or does not send] an EDNS Keepalive option.
+[no]keepopen
This option keeps [or does not keep] the TCP socket open between
queries, and reuses it rather than creating a new TCP socket for
each lookup. The default is +nokeepopen.
+[no]mapped
This option allows [or does not allow] mapped IPv4-over-IPv6
addresses to be used. The default is +mapped.
+[no]multiline
This option prints [or does not print] records, like the SOA
records, in a verbose multi-line format with human-readable com-
ments. The default is to print each record on a single line to
facilitate machine parsing of the dig output.
+ndots=D
This option sets the number of dots (D) that must appear in name
for it to be considered absolute. The default value is that
defined using the ndots statement in /etc/resolv.conf, or 1 if
no ndots statement is present. Names with fewer dots are inter-
preted as relative names, and are searched for in the domains
listed in the search or domain directive in /etc/resolv.conf if
+search is set.
+[no]nsid
When enabled, this option includes an EDNS name server ID
request when sending a query.
+[no]nssearch
When this option is set, dig attempts to find the authoritative
name servers for the zone containing the name being looked up,
and display the SOA record that each name server has for the
zone. Addresses of servers that did not respond are also
printed.
+[no]onesoa
When enabled, this option prints only one (starting) SOA record
when performing an AXFR. The default is to print both the start-
ing and ending SOA records.
+[no]opcode=value
When enabled, this option sets (restores) the DNS message opcode
to the specified value. The default value is QUERY (0).
+padding=value
This option pads the size of the query packet using the EDNS
Padding option to blocks of value bytes. For example, +pad-
ding=32 causes a 48-byte query to be padded to 64 bytes. The
default block size is 0, which disables padding; the maximum is
512. Values are ordinarily expected to be powers of two, such as
128; however, this is not mandatory. Responses to padded queries
may also be padded, but only if the query uses TCP or DNS
COOKIE.
+[no]qr
This option toggles the display of the query message as it is
sent. By default, the query is not printed.
+[no]question
This option toggles the display of the question section of a
query when an answer is returned. The default is to print the
question section as a comment.
+[no]raflag
This option sets [or does not set] the RA (Recursion Available)
bit in the query. The default is +noraflag. This bit is ignored
by the server for QUERY.
+[no]rdflag
This option is a synonym for +[no]recurse.
+[no]recurse
This option toggles the setting of the RD (recursion desired)
bit in the query. This bit is set by default, which means dig
normally sends recursive queries. Recursion is automatically
disabled when the +nssearch or +trace query option is used.
+retry=T
This option sets the number of times to retry UDP and TCP
queries to server to T instead of the default, 2. Unlike
+tries, this does not include the initial query.
+[no]rrcomments
This option toggles the display of per-record comments in the
output (for example, human-readable key information about DNSKEY
records). The default is not to print record comments unless
multiline mode is active.
+[no]search
This option uses [or does not use] the search list defined by
the searchlist or domain directive in resolv.conf, if any. The
search list is not used by default.
ndots from resolv.conf (default 1), which may be overridden by
+ndots, determines whether the name is treated as relative and
hence whether a search is eventually performed.
+[no]short
This option toggles whether a terse answer is provided. The
default is to print the answer in a verbose form. This option
always has a global effect; it cannot be set globally and then
overridden on a per-lookup basis.
+[no]showsearch
This option performs [or does not perform] a search showing
intermediate results.
+[no]sigchase
This feature is now obsolete and has been removed; use delv
instead.
+split=W
This option splits long hex- or base64-formatted fields in
resource records into chunks of W characters (where W is rounded
up to the nearest multiple of 4). +nosplit or +split=0 causes
fields not to be split at all. The default is 56 characters, or
44 characters when multiline mode is active.
+[no]stats
This option toggles the printing of statistics: when the query
was made, the size of the reply, etc. The default behavior is to
print the query statistics as a comment after each lookup.
+[no]subnet=addr[/prefix-length]
This option sends [or does not send] an EDNS CLIENT-SUBNET
option with the specified IP address or network prefix.
dig +subnet=0.0.0.0/0, or simply dig +subnet=0 for short, sends
an EDNS CLIENT-SUBNET option with an empty address and a source
prefix-length of zero, which signals a resolver that the
client's address information must not be used when resolving
this query.
+[no]tcflag
This option sets [or does not set] the TC (TrunCation) bit in
the query. The default is +notcflag. This bit is ignored by the
server for QUERY.
+[no]tcp
This option uses [or does not use] TCP when querying name
servers. The default behavior is to use UDP unless a type any or
ixfr=N query is requested, in which case the default is TCP.
AXFR queries always use TCP.
+timeout=T
This option sets the timeout for a query to T seconds. The
default timeout is 5 seconds. An attempt to set T to less than 1
is silently set to 1.
+[no]topdown
This feature is related to dig +sigchase, which is obsolete and
has been removed. Use delv instead.
+[no]trace
This option toggles tracing of the delegation path from the root
name servers for the name being looked up. Tracing is disabled
by default. When tracing is enabled, dig makes iterative queries
to resolve the name being looked up. It follows referrals from
the root servers, showing the answer from each server that was
used to resolve the lookup.
If @server is also specified, it affects only the initial query
for the root zone name servers.
+dnssec is also set when +trace is set, to better emulate the
default queries from a name server.
+tries=T
This option sets the number of times to try UDP and TCP queries
to server to T instead of the default, 3. If T is less than or
equal to zero, the number of tries is silently rounded up to 1.
+trusted-key=####
This option formerly specified trusted keys for use with dig
+sigchase. This feature is now obsolete and has been removed;
use delv instead.
+[no]ttlid
This option displays [or does not display] the TTL when printing
the record.
+[no]ttlunits
This option displays [or does not display] the TTL in friendly
human-readable time units of s, m, h, d, and w, representing
seconds, minutes, hours, days, and weeks. This implies +ttlid.
+[no]unexpected
This option accepts [or does not accept] answers from unexpected
sources. By default, dig will not accept a reply from a source
other than the one to which it sent the query.
+[no]unknownformat
This option prints all RDATA in unknown RR type presentation
format (RFC 3597). The default is to print RDATA for known
types in the type's presentation format.
+[no]vc
This option uses [or does not use] TCP when querying name
servers. This alternate syntax to +[no]tcp is provided for back-
wards compatibility. The vc stands for "virtual circuit."
+[no]yaml
When enabled, this option prints the responses (and, if +qr is
in use, also the outgoing queries) in a detailed YAML format.
+[no]zflag
This option sets [or does not set] the last unassigned DNS
header flag in a DNS query. This flag is off by default.
MULTIPLE QUERIES
The BIND 9 implementation of dig supports specifying multiple queries
on the command line (in addition to supporting the -f batch file
option). Each of those queries can be supplied with its own set of
flags, options, and query options.
In this case, each query argument represents an individual query in the
command-line syntax described above. Each consists of any of the stan-
dard options and flags, the name to be looked up, an optional query
type and class, and any query options that should be applied to that
query.
A global set of query options, which should be applied to all queries,
can also be supplied. These global query options must precede the first
tuple of name, class, type, options, flags, and query options supplied
on the command line. Any global query options (except +[no]cmd and
+[no]short options) can be overridden by a query-specific set of query
options. For example:
dig +qr www.isc.org any -x 127.0.0.1 isc.org ns +noqr
shows how dig can be used from the command line to make three lookups:
an ANY query for www.isc.org, a reverse lookup of 127.0.0.1, and a
query for the NS records of isc.org. A global query option of +qr is
applied, so that dig shows the initial query it made for each lookup.
The final query has a local query option of +noqr which means that dig
does not print the initial query when it looks up the NS records for
isc.org.
IDN SUPPORT
If dig has been built with IDN (internationalized domain name) support,
it can accept and display non-ASCII domain names. dig appropriately
converts character encoding of a domain name before sending a request
to a DNS server or displaying a reply from the server. To turn off IDN
support, use the parameters +noidnin and +noidnout, or define the
IDN_DISABLE environment variable.
RETURN CODES
dig return codes are:
0 DNS response received, including NXDOMAIN status
1 Usage error
8 Couldn't open batch file
9 No reply from server
10 Internal error
FILES
/etc/resolv.conf
${HOME}/.digrc
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
+---------------+--------------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+--------------------------+
|Availability | network/dns/bind |
+---------------+--------------------------+
|Stability | Pass-through uncommitted |
+---------------+--------------------------+
SEE ALSO
delv(1), host(1), named(8), dnssec-keygen(8), RFC 1035.
BUGS
There are probably too many query options.
AUTHOR
Internet Systems Consortium
COPYRIGHT
2022, Internet Systems Consortium
NOTES
Source code for open source software components in Oracle Solaris can
be found at https://www.oracle.com/downloads/opensource/solaris-source-
code-downloads.html.
This software was built from source available at
https://github.com/oracle/solaris-userland. The original community
source was downloaded from
http://ftp.isc.org/isc/bind9/9.16.29/bind-9.16.29.tar.xz.
Further information about this software can be found on the open source
community website at http://www.isc.org/software/bind/.
9.16.29 2022-05-10 DIG(1)