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 clar-
ity 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. Unlike earlier versions, the BIND 9 implementa-
tion of dig allows multiple lookups to be issued from the command line.
Unless it is told to query a specific name server, dig will try each of
the servers listed in /etc/resolv.conf. If no usable server addresses
are found, dig will send the query to the local host.
When no command line arguments or options are given, dig will perform
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 command
line arguments. The -r option disables this feature, for scripts that
need predictable behaviour.
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 the 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/re-
solv.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 will be
tried. If no usable addresses are found, dig will send 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 MDASH ANY, A, MX, SIG,
etc. type can be any valid query type. If no type argument is
supplied, dig will perform a lookup for an A record.
OPTIONS
-4 Use IPv4 only.
-6 Use IPv6 only.
-b address[#port]
Set 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 append-
ing "#<port>"
-c class
Set the query class. The default class is IN; other classes are
HS for Hesiod records or CH for Chaosnet records.
-f file
Batch mode: 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 they would be presented as queries to dig using the
command-line interface.
-k keyfile
Sign queries using TSIG using a key read from the given file.
Key files can be generated using tsig-keygen8. 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 Enable memory usage debugging.
-p port
Send the query to a non-standard port on the server, instead of
the default port 53. This option would be used to test a name
server that has been configured to listen for queries on a
non-standard port number.
-q name
The domain name to query. This is useful to distinguish the name
from other arguments.
-r Do not read options from ${HOME}/.digrc. This is useful for
scripts that need predictable behaviour.
-t type
The resource record type to query. It 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 incremental zone transfer
(IXFR) is required, set the type to ixfr=N. The incremental zone
transfer will contain the changes made to the zone since the se-
rial 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 will be displayed as de-
scribed in RFC 3597.
-u Print query times in microseconds instead of milliseconds.
-v Print the version number and exit.
-x addr
Simplified reverse lookups, for mapping addresses to names. The
addr is an IPv4 address in dotted-decimal notation, or a
colon-delimited IPv6 address. When the -x is used, there is no
need to provide the name, class and type arguments. dig auto-
matically 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
Sign queries using TSIG with the given authentication key. key-
name is the name of the key, and secret is the base64 encoded
shared secret. hmac is the name of the key algorithm; valid
choices are hmac-md5, hmac-sha1, hmac-sha224, hmac-sha256,
hmac-sha384, or hmac-sha512. If hmac is not specified, the de-
fault is hmac-md5 or if MD5 was disabled hmac-sha256.
NOTE:
You should use the -k option and avoid 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 an-
swer 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 op-
tions are:
+[no]aaflag
A synonym for +[no]aaonly.
+[no]aaonly
Sets the "aa" flag in the query.
+[no]additional
Display [do not display] the additional section of a reply. The
default is to display it.
+[no]adflag
Set [do not set] the AD (authentic data) bit in the query. This
requests the server to return whether all of the answer and au-
thority sections have all 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 indicate that some part of the answer was
insecure or not validated. This bit is set by default.
+[no]all
Set or clear all display flags.
+[no]answer
Display [do not display] the answer section of a reply. The de-
fault is to display it.
+[no]authority
Display [do not display] the authority section of a reply. The
default is to display it.
+[no]badcookie
Retry lookup with the new server cookie if a BADCOOKIE response
is received.
+[no]besteffort
Attempt 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 a EDNS messages with a advertised size
of 0 bytes). +bufsize restores the default buffer size.
+[no]cdflag
Set [do not set] the CD (checking disabled) bit in the query.
This requests the server to not perform DNSSEC validation of re-
sponses.
+[no]class
Display [do not display] the CLASS when printing the record.
+[no]cmd
Toggles the printing of the initial comment in the output, iden-
tifying the version of dig and the query options that have been
applied. This option always has global effect; it cannot be set
globally and then overridden on a per-lookup basis. The default
is to print this comment.
+[no]comments
Toggles the display of some comment lines in the output, con-
taining information about the packet header and OPT pseudosec-
tion, 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=####
Send a COOKIE EDNS option, with optional value. Replaying a
COOKIE from a previous response will allow the server to iden-
tify a previous client. The default is +cookie.
+cookie is also set when +trace is set to better emulate the de-
fault queries from a nameserver.
+[no]crypto
Toggle the display of cryptographic fields in DNSSEC records.
The contents of these field are unnecessary to debug 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
Deprecated, treated as a synonym for +[no]search
+[no]dnssec
Requests DNSSEC records be sent by setting the DNSSEC OK bit
(DO) in the OPT record in the additional section of the query.
+domain=somename
Set the search list to contain the single domain somename, as if
specified in a domain directive in /etc/resolv.conf, and enable
search list processing as if the +search option were given.
+dscp=value
Set 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[=#]
Specify the EDNS version to query with. Valid values are 0 to
255. Setting the EDNS version will cause a EDNS query to be
sent. +noedns clears the remembered EDNS version. EDNS is set
to 0 by default.
+[no]ednsflags[=#]
Set 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) will silently be ignored. By default, no Z
bits are set.
+[no]ednsnegotiation
Enable / disable EDNS version negotiation. By default EDNS ver-
sion negotiation is enabled.
+[no]ednsopt[=code[:value]]
Specify EDNS option with code point code and optionally payload
of value as a hexadecimal string. code can be either an EDNS op-
tion name (for example, NSID or ECS), or an arbitrary numeric
value. +noednsopt clears the EDNS options to be sent.
+[no]expire
Send an EDNS Expire option.
+[no]fail
Do not try the next server if you receive a SERVFAIL. The de-
fault is to not try the next server which is the reverse of nor-
mal stub resolver behavior.
+[no]header-only
Send 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
Show [or do not show] the IP address and port number that sup-
plied 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
Process [do not process] IDN domain names on input. This re-
quires 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
Convert [do 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
Ignore truncation in UDP responses instead of retrying with TCP.
By default, TCP retries are performed.
+[no]keepalive
Send [or do not send] an EDNS Keepalive option.
+[no]keepopen
Keep the TCP socket open between queries and reuse it rather
than creating a new TCP socket for each lookup. The default is
+nokeepopen.
+[no]mapped
Allow mapped IPv4 over IPv6 addresses to be used. The default is
+mapped.
+[no]multiline
Print records like the SOA records in a verbose multi-line for-
mat with human-readable comments. The default is to print each
record on a single line, to facilitate machine parsing of the
dig output.
+ndots=D
Set the number of dots that have to appear in name to D for it
to be considered absolute. The default value is that defined us-
ing the ndots statement in /etc/resolv.conf, or 1 if no ndots
statement is present. Names with fewer dots are interpreted as
relative names and will be searched for in the domains listed in
the search or domain directive in /etc/resolv.conf if +search is
set.
+[no]nsid
Include 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 that did not respond are also
printed.
+[no]onesoa
Print only one (starting) SOA record when performing an AXFR.
The default is to print both the starting and ending SOA
records.
+[no]opcode=value
Set [restore] the DNS message opcode to the specified value. The
default value is QUERY (0).
+padding=value
Pad the size of the query packet using the EDNS Padding option
to blocks of value bytes. For example, +padding=32 would cause 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 or-
dinarily 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
Toggles the display of the query message as it is sent. By de-
fault, the query is not printed.
+[no]question
Toggles the display of the question section of a query when an
answer is returned. The default is to print the question sec-
tion as a comment.
+[no]raflag
Set [do not set] the RA (Recursion Available) bit in the query.
The default is +noraflag. This bit should be ignored by the
server for QUERY.
+[no]rdflag
A synonym for +[no]recurse.
+[no]recurse
Toggle 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 options are used.
+retry=T
Sets the number of times to retry UDP queries to server to T in-
stead of the default, 2. Unlike +tries, this does not include
the initial query.
+[no]rrcomments
Toggle the display of per-record comments in the output (for ex-
ample, human-readable key information about DNSKEY records). The
default is not to print record comments unless multiline mode is
active.
+[no]search
Use [do 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 if the name will be treated as relative or not
and hence whether a search is eventually performed or not.
+[no]short
Provide a terse answer. The default is to print the answer in a
verbose form. This option always has global effect; it cannot
be set globally and then overridden on a per-lookup basis.
+[no]showsearch
Perform [do not perform] a search showing intermediate results.
+[no]sigchase
This feature is now obsolete and has been removed; use delv in-
stead.
+split=W
Split long hex- or base64-formatted fields in resource records
into chunks of W characters (where W is rounded up to the near-
est 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
Toggles the printing of statistics: when the query was made, the
size of the reply and so on. The default behavior is to print
the query statistics as a comment after each lookup.
+[no]subnet=addr[/prefix-length]
Send (don't send) an EDNS Client Subnet option with the speci-
fied 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
Set [do not set] the TC (TrunCation) bit in the query. The de-
fault is +notcflag. This bit should be ignored by the server for
QUERY.
+[no]tcp
Use [do not use] TCP when querying name servers. The default be-
havior is to use UDP unless a type any or ixfr=N query is re-
quested, in which case the default is TCP. AXFR queries always
use TCP.
+timeout=T
Sets the timeout for a query to T seconds. The default timeout
is 5 seconds. An attempt to set T to less than 1 will result in
a query timeout of 1 second being applied.
+[no]topdown
This feature is related to dig +sigchase, which is obsolete and
has been removed. Use delv instead.
+[no]trace
Toggle 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 will follow 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 de-
fault queries from a nameserver.
+tries=T
Sets the number of times to try UDP queries to server to T in-
stead 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=####
Formerly specified trusted keys for use with dig +sigchase. This
feature is now obsolete and has been removed; use delv instead.
+[no]ttlid
Display [do not display] the TTL when printing the record.
+[no]ttlunits
Display [do not display] the TTL in friendly human-readable time
units of "s", "m", "h", "d", and "w", representing seconds, min-
utes, hours, days and weeks. Implies +ttlid.
+[no]unexpected
Accept [do not accept] answers from unexpected sources. By de-
fault, dig won't accept a reply from a source other than the one
to which it sent the query.
+[no]unknownformat
Print 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
Use [do not use] TCP when querying name servers. This alternate
syntax to +[no]tcp is provided for backwards compatibility. The
"vc" stands for "virtual circuit".
+[no]yaml
Print the responses (and, if <option>+qr</option> is in use,
also the outgoing queries) in a detailed YAML format.
+[no]zflag
Set [do 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 op-
tion). Each of those queries can be supplied with its own set of flags,
options and query options.
In this case, each query argument represent 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 could 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 will 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 domain name before sending a request to
DNS server or displaying a reply from the server. If you'd like to turn
off the IDN support for some reason, use parameters +noidnin and +noid-
nout or define the IDN_DISABLE environment variable.
FILES
/etc/resolv.conf
${HOME}/.digrc
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
2020, Internet Systems Consortium
9.16.8-Debian 2020-10-13 DIG(1)