MDIG(1) BIND 9 MDIG(1)

NAME

mdig - DNS pipelined lookup utility

SYNOPSIS

mdig {@server} [-f filename] [-h] [-v] [ [-4] | [-6] ] [-m] [-b
address] [-p port#] [-c class] [-t type] [-i] [-x addr] [plusopt...]

mdig {-h}

mdig [@server] {global-opt...} { {local-opt...} {query} ...}

DESCRIPTION

mdig is a multiple/pipelined query version of dig: instead of waiting
for a response after sending each query, it begins by sending all
queries. Responses are displayed in the order in which they are
received, not in the order the corresponding queries were sent.

mdig options are a subset of the dig options, and are divided into
"anywhere options," which can occur anywhere, "global options," which
must occur before the query name (or they are ignored with a
warning), and "local options," which apply to the next query on the
command line.

The @server option is a mandatory global option. It is the name or IP
address of the name server to query. (Unlike dig, this value is not
retrieved from /etc/resolv.conf.) It can be an IPv4 address in
dotted-decimal notation, an IPv6 address in colon-delimited notation,
or a hostname. When the supplied server argument is a hostname, mdig
resolves that name before querying the name server.

mdig 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.

ANYWHERE OPTIONS

-f This option makes mdig 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 mdig using the command-line interface.

-h This option causes mdig to print detailed help information,
with the full list of options, and exit.

-v This option causes mdig to print the version number and exit.

GLOBAL OPTIONS

-4 This option forces mdig to only use IPv4 query transport.

-6 This option forces mdig to only use IPv6 query transport.

-b address
This 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>"

-m This option enables memory usage debugging.

-p port#
This option is used when a non-standard port number is to be
queried. port# is the port number that mdig sends its queries
to, instead of the standard DNS port number 53. This option is
used to test a name server that has been configured to listen
for queries on a non-standard port number.

The global query options are:

+additional, +noadditional
This option displays [or does not display] the additional
section of a reply. The default is to display it.

+all, +noall
This option sets or clears all display flags.

+answer, +noanswer
This option displays [or does not display] the answer section
of a reply. The default is to display it.

+authority, +noauthority
This option displays [or does not display] the authority
section of a reply. The default is to display it.

+besteffort, +nobesteffort
This option attempts to display [or does not display] the
contents of messages which are malformed. The default is to
not display malformed answers.

+burst This option delays queries until the start of the next second.

+cl, +nocl
This option displays [or does not display] the CLASS when
printing the record.

+comments, +nocomments
This option toggles the display of comment lines in the
output. The default is to print comments.

+continue, +nocontinue
This option toggles continuation on errors (e.g. timeouts).

+crypto, +nocrypto
This option toggles the display of cryptographic fields in
DNSSEC records. The contents of these fields 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]"; in the DNSKEY case, the key ID is
displayed as the replacement, e.g., [ key id = value ].

+dscp=value
This option formerly set the DSCP value used when sending a
query. It is now obsolete, and has no effect.

+multiline, +nomultiline
This option toggles printing of 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 mdig output.

+question, +noquestion
This option prints [or does not print] the question section of
a query when an answer is returned. The default is to print
the question section as a comment.

+rrcomments, +norrcomments
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.

+short, +noshort
This option provides [or does not provide] a terse answer. The
default is to print the answer in a verbose form.

+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. The default is 56 characters,
or 44 characters when multiline mode is active.

+tcp, +notcp
This option uses [or does not use] TCP when querying name
servers. The default behavior is to use UDP.

+ttlid, +nottlid
This option displays [or does not display] the TTL when
printing the record.

+ttlunits, +nottlunits
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.

+vc, +novc
This option uses [or does not use] TCP when querying name
servers. This alternate syntax to +tcp is provided for
backwards compatibility. The vc stands for "virtual circuit".

LOCAL OPTIONS

-c class
This option sets the query class to class. It can be any valid
query class which is supported in BIND 9. The default query
class is "IN".

-t type
This 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 with the "PTR" query type.

-x addr
Reverse lookups - mapping addresses to names - are simplified
by this option. addr is an IPv4 address in dotted-decimal
notation, or a colon-delimited IPv6 address. mdig
automatically performs a lookup for a query 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.

The local query options are:

+aaflag, +noaaflag
This is a synonym for +aaonly, +noaaonly.

+aaonly, +noaaonly
This sets the aa flag in the query.

+adflag, +noadflag
This 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 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 indicates that
some part of the answer was insecure or not validated. This
bit is set by default.

+bufsize=B
This 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. Values outside this range are
rounded up or down appropriately. Values other than zero cause
a EDNS query to be sent.

+cdflag, +nocdflag
This sets [or does not set] the CD (checking disabled) bit in
the query. This requests the server to not perform DNSSEC
validation of responses.

+cookie=####, +nocookie
This 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 +nocookie.

+dnssec, +nodnssec
This requests that DNSSEC records be sent by setting the
DNSSEC OK (DO) bit in the OPT record in the additional section
of the query.

+edns[=#], +noedns
This specifies [or does not specify] the EDNS version to query
with. Valid values 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.

+ednsflags[=#], +noednsflags
This sets the must-be-zero EDNS flag 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.

+ednsopt[=code[:value]], +noednsopt
This specifies [or does not specify] an EDNS option with code
point code and an optional payload of value as a hexadecimal
string. +noednsopt clears the EDNS options to be sent.

+expire, +noexpire
This toggles sending of an EDNS Expire option.

+nsid, +nonsid
This toggles inclusion of an EDNS name server ID request when
sending a query.

+recurse, +norecurse
This toggles the setting of the RD (recursion desired) bit in
the query. This bit is set by default, which means mdig
normally sends recursive queries.

+retry=T
This 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.

+subnet=addr[/prefix-length], +nosubnet
This sends [or does not send] an EDNS Client Subnet option
with the specified IP address or network prefix.

mdig +subnet=0.0.0.0/0, or simply mdig +subnet=0
This 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.

+timeout=T
This sets the timeout for a query to T seconds. The default
timeout is 5 seconds for UDP transport and 10 for TCP. An
attempt to set T to less than 1 results in a query timeout of
1 second being applied.

+tries=T
This 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.

+udptimeout=T
This sets the timeout between UDP query retries to T.

+unknownformat, +nounknownformat
This prints [or does not print] all RDATA in unknown RR-type
presentation format (see RFC 3597). The default is to print
RDATA for known types in the type's presentation format.

+yaml, +noyaml
This toggles printing of the responses in a detailed YAML
format.

+zflag, +nozflag
This sets [or does not set] the last unassigned DNS header
flag in a DNS query. This flag is off by default.

SEE ALSO

dig(1), RFC 1035.

AUTHOR

Internet Systems Consortium

COPYRIGHT

2025, Internet Systems Consortium

9.18.34 2025-02-11 MDIG(1)