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.
Syntax:
dig [@global-server] [domain] [q-type] [q-class] {q-opt} {global-d-opt}
host [@local-server] {local-d-opt}
[ host [@local-server] {local-d-opt} [...]]
Where:
domain is in the Domain Name System
q-class is one of (in, hs, ch, ...) [default: in]
q-type is one of (a, any, mx, ns, soa, hinfo, axfr, txt,...) [default:a]
(Use ixfr=version for type ixfr)
q-opt is one of:
-4 Force dig to only use IPv4 query transport.
-6 Force dig to only use IPv6 query transport.
-b address [#port]
Bind to the source IP address/port.
This must be a valid address on one of the host’s network interfaces or "0.0.0.0" or "::".
An optional port can be specified by appending "#port"
-c class
Over-ride the default query class (IN for internet).
class is any valid class, such as HS for Hesiod records or CH for CHAOSNET records.
-f filename
Operate in batch mode by reading a list of lookup requests to process from a file.
The file contains a number of queries, one per line.
Each entry in the file should be organised in the same way they would be presented
as queries to dig using the command-line interface.
-i Use IP6.INT for IPv6 reverse lookups.
-k keyfile Specify tsig key file.
Sign the DNS queries sent by dig and their responses using transaction signatures
(TSIG key file). You can also specify the TSIG key itself on the command line
using the -y option; name is the name of the TSIG key and key is the actual key.
The key is a base-64 encoded string, typically generated by dnssec-keygen(8).
Caution should be taken when using the -y option on multi-user systems as the key
can be visible in the output from ps(1 ) or in the shell’s history file.
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#
Specify a non-standard port number to be queried,
default = the standard DNS port number 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 Specify query name
-t type
Set the query type to type, any valid query type which is supported in BIND9.
The default query type "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, type is set 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.
-u Display times in usec instead of msec.
-x addr
Reverse lookups - mapping addresses to names: addr is an IPv4 address in dotted-
decimal notation, or a colon-delimited IPv6 address. When this option is used,
there is no need to provide the name, class and type arguments. dig automatically
performs a lookup for a name like 11.12.13.10.in-addr.arpa and sets the query type
and class to PTR and IN respectively. By default, IPv6 addresses are looked up using
nibble format under the IP6.ARPA domain. To use the older RFC1886 method using the
IP6.INT domain specify the -i option. Bit string labels (RFC2874) are now experimental
and are not attempted.
d-opt is of the form +keyword[=value], where keyword is:
+[no]aaonly
Sets the "aa" flag in the query.
+[no]aaflag
A synonym for +[no]aaonly.
+[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.
+[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]cl
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]crypto
Control display of cryptographic fields in records.
+[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.
+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.
+ednsflags=###
Set EDNS flag bits.
+[no]ednsnegotiation
Set EDNS version negotiation.
+noednsopt
Clear list of +ednsopt options.
+[no]expire
Request time to expire.
+[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 IDN response.
+[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.
+[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.
+[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
AXFR prints only one soa record.
+[no]opcode=###
Set the opcode of the request.
+[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]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
Control display of per-record comments.
+[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.
+[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]split=##
Split hex/base64 fields into chunks.
+[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.
+subnet=addr
Set edns-client-subnet option.
+[no]tcp
Use [do not use] TCP when querying name servers. The default
behavior is to use UDP unless an AXFR or IXFR query is requested,
in which case a TCP connection is used.
+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]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.
+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.
+[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".
global d-opts and servers (before host name) affect all queries.
local d-opts and servers (after host name) affect only that lookup.
-h Print a brief summary of the command-line arguments and options.
-v Print version and exit.
Although dig is normally used with command-line arguments, it also has a batch mode of operation for reading lookup requests from a file. Unlike earlier versions, the BIND9 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
When no command line arguments or options are given, 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 domains 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.
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 might differ from those found by other processes that use the macOS native name
and address resolution mechanisms. The results of DNS queries can also
differ from queries that use the macOS DNS routing library.
A (Host address)
AAAA (IPv6 host address)
ALIAS (Auto resolved alias)
CNAME (Canonical name for an alias)
MX (Mail eXchange)
NS (Name Server)
PTR (Pointer)
SOA (Start Of Authority)
SRV (location of service)
TXT (Descriptive text)
List the DNS A records for ss64.com:
$ dig ss64.com
or
$ dig ss64.com A
List the DNS AAAA (ipv6) records for ss64.com:
$ dig ss64.com AAAA
List the DNS A records for ss64.com using Google DNS (8.8.8.8) instead of your local cache:
$ dig ss64.com @8.8.8.8
List the Signature record (SIG record) for ss64.com:
$ dig ss64.com SIG
List the Mail exchanger record (MX record) for ss64.com:
$ dig ss64.com MX
Test your DNS resolver’s source port behavior:
$ dig +short porttest.dns-oarc.net TXT
“Businessmen they drink my wine, Plowmen dig my earth, But none of them along the line, Know what any of it is worth” ~ Bob Dylan
dscacheutil - Query or flush the Directory Service/DNS cache.
Dig web interface - Online Dig.
ViewDNS.info - Online IP and DNS lookups.