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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 ig‐
nored 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 deter‐
mine 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 key‐
word. 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 op‐
tions, 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 de‐
fault 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 de‐
fault 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 con‐
tents of these fields are unnecessary to debug most DNSSEC validation failures and re‐
moving 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 obso‐
lete, 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, hu‐
man-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 charac‐
ters when multiline mode is active.

+tcp, +notcp
This option uses [or does not use] TCP when querying name servers. The default behav‐
ior 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 syn‐
tax to +tcp is provided for backwards compatibility. The vc stands for "virtual cir‐
cuit".

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 sup‐
ported 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 ig‐
nored. 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 op‐
tional 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 de‐
fault, 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 ad‐
dress 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 pre‐
fix-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 de‐
fault, 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.