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

The -b option sets the source IP address of the query to address. This
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>"

The default query class (IN for internet) is overridden by the -c option.
class is any valid class, such as HS for Hesiod records or CH for
Chaosnet records.

The -f option makes dig operate in batch mode by reading a list of
lookup requests to process from the file filename. The file contains a
number of queries, one per line. Each entry in the file should be
organized in the same way they would be presented as queries to dig using
the command-line interface.

The -m option enables memory usage debugging.

If a non-standard port number is to be queried, the -p option is used.
port# is the port number that dig will send its queries instead of 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.

The -4 option forces dig to only use IPv4 query transport. The -6 option
forces dig to only use IPv6 query transport.

The -t option sets the query type to type. 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, 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.

The -q option sets the query name to name. This is useful to distinguish
the name from other arguments.

The -v causes dig to print the version number and exit.

Reverse lookups -- mapping addresses to names -- are simplified by the -x
option. 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.

To sign the DNS queries sent by dig and their responses using transaction
signatures (TSIG), specify a TSIG key file using the -k option. You can
also specify the TSIG key itself on the command line using the -y option;
hmac is the type of the TSIG, default HMAC-MD5, 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.

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. 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]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
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]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]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.

+[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]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
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.

+[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.

+[no]sit[=####]
Send a Source Identity Token EDNS option, with optional value.
Replaying a SIT from a previous response will allow the server to
identify a previous client. The default is +nosit. Currently using
experimental value 65001 for the option code.

+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
Send an EDNS Client Subnet option with the specified IP address or
network prefix.

+[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.

+[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.

+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.

+[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

host(1), named(8), dnssec-keygen(8), RFC1035.

BUGS

There are probably too many query options.

COPYRIGHT

Copyright (C) 2004-2011, 2013, 2014 Internet Systems Consortium, Inc.
("ISC")
Copyright (C) 2000-2003 Internet Software Consortium.

BIND9 February 19, 2014 DIG(1)