DIG(1) BIND9 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 (domain information groper) 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 troubleshoot 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. Unlike earlier versions, the BIND 9 implementation 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 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/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 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 — 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 appending "#<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.
-i
Do reverse IPv6 lookups using the obsolete RFC1886 IP6.INT domain,
which is no longer in use. Obsolete bit string label queries
(RFC2874) are not attempted.
-k keyfile
Sign queries using TSIG using a key read from the given file. Key
files can be generated using tsig-keygen(8). 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
defaut 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.
-t type
The resource record type to query. It can be any valid query type
which is supported in BIND 9. 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 serial number in the zone's SOA record was N.
-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 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 (but see also the -i option).
-y [hmac:]keyname:secret
Sign queries using TSIG with the given authentication key. keyname
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 default 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 ps(1) or in a
history file maintained by the user's shell.
macOS NOTICE
The dig command does not use the host name and address resolution or the
DNS query routing mechanisms used by other processes running on macOS.
The results of name or address queries printed by dig may differ from
those found by other processes that use the macOS native name and address
resolution mechanisms. The results of DNS queries may also differ from
queries that use the macOS DNS routing library.
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
strategies.
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 +keyword=value.
Keywords may be abbreviated, provided the abbreviation is unambiguous;
for example, +cd is equivalent to +cdflag. The query options 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 authority
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 default
is to display it.
+[no]authority
Display [do not display] the authority section of a reply. The
default is to display it.
+[no]besteffort
Attempt to display the contents of messages which are malformed. The
default is to not display malformed answers.
+bufsize=B
Set the UDP message buffer size advertised using EDNS0 to B bytes.
The maximum and minimum sizes of this buffer are 65535 and 0
respectively. Values outside this range are rounded up or down
appropriately. Values other than zero will cause a EDNS query to be
sent.
+[no]cdflag
Set [do not set] the CD (checking disabled) bit in the query. This
requests the server to not perform DNSSEC validation of responses.
+[no]class
Display [do not display] the CLASS when printing the record.
+[no]cmd
Toggles the printing of the initial comment in the output identifying
the version of dig and the query options that have been applied. This
comment is printed by default.
+[no]comments
Toggle the display of comment lines in the output. The default is to
print comments.
+[no]cookie[=####]
Send an COOKIE EDNS option, containing an optional value. Replaying a
COOKIE from a previous response will allow the server to identify a
previous client. The default is +nocookie.
+cookie is automatically set when +trace is in use, to better emulate
the default queries from a nameserver.
This option was formerly called +[no]sit (Server Identity Token). In
BIND 9.10.0 through BIND 9.10.2, it sent the experimental option code
65001. This was changed to option code 10 in BIND 9.10.3 when the DNS
COOKIE option was allocated.
The +[no]sit is now deprecated, but has been retained as a synonym
for +[no]cookie for backward compatibility within the BIND 9.10
branch.
+[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.
+[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 version
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 option
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 default is
to not try the next server which is the reverse of normal stub
resolver behavior.
+[no]identify
Show [or do 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]idnout
Convert [do not convert] puny code on output. This requires IDN
SUPPORT to have been enabled at compile time. The default is to
convert output.
+[no]ignore
Ignore truncation in UDP responses instead of retrying with TCP. By
default, TCP retries are performed.
+[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]multiline
Print records like the SOA records in a verbose multi-line format
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 using 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.
+[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).
+[no]qr
Print [do not print] the query as it is sent. By default, the query
is not printed.
+[no]question
Print [do not print] the question section of a query when an answer
is returned. The default is to print the question section as a
comment.
+[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 instead
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 example,
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.
+[no]showsearch
Perform [do not perform] a search showing intermediate results.
+[no]sigchase
Chase DNSSEC signature chains. Requires dig be compiled with
-DDIG_SIGCHASE. This feature is deprecated. Use delv instead.
+[no]sit[=####]
This option is a synonym for +[no]cookie.
The +[no]sit is deprecated.
+split=W
Split 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 query option 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.
+[no]subnet=addr[/prefix-length]
Send (don't 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]tcp
Use [do not use] TCP when querying name servers. The default behavior
is to use UDP unless an ixfr=N query is requested, in which case the
default is TCP. AXFR queries always use TCP.
+time=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
When chasing DNSSEC signature chains perform a top-down validation.
Requires dig be compiled with -DDIG_SIGCHASE. This feature is
deprecated. 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 default
queries from a nameserver.
+tries=T
Sets the number of times to try UDP 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=####
Specifies a file containing trusted keys to be used with +sigchase.
Each DNSKEY record must be on its own line.
If not specified, dig will look for /etc/trusted-key.key then
trusted-key.key in the current directory.
Requires dig be compiled with -DDIG_SIGCHASE. This feature is
deprecated. Use delv instead.
+[no]ttlid
Display [do not display] the TTL when printing the record.
+[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".
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 represent an individual query in the
command-line syntax described above. Each consists of any of the standard
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 the +[no]cmd option)
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, defines the IDN_DISABLE environment
variable. The IDN support is disabled if the variable is set when dig
runs.
FILES
/etc/resolv.conf
${HOME}/.digrc
SEE ALSO
delv(1), host(1), named(8), dnssec-keygen(8), RFC1035.
BUGS
There are probably too many query options.
AUTHOR
Internet Systems Consortium, Inc.
COPYRIGHT
Copyright © 2004-2011, 2013-2017 Internet Systems Consortium, Inc.
("ISC")
Copyright © 2000-2003 Internet Software Consortium.
ISC 2018-05-25 DIG(1)