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
The {@server} option is a mandatory global
option. It is the name or IP address of the name server to query.
(Unlike <
span class="command"><
strong>dig</
strong></
span>, this value is not retrieved from
<
code class="filename">/
etc/
resolv.conf</
code>.) It can be an IPv4 address
in dotted-decimal notation, an IPv6 address in colon-delimited
notation, or a hostname. When the supplied
<
em class="parameter"><
code>server</
code></
em> argument is a hostname,
<
span class="command"><
strong>mdig</
strong></
span> resolves that name before querying
<
p><
span class="command"><
strong>mdig</
strong></
span>
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
Each query option is identified by a keyword preceded by a plus
sign (<
code class="literal">+</
code>). Some keywords set or reset an
option. These may be preceded by the string <
code class="literal">no</
code>
to negate the meaning of that keyword. Other keywords assign
values to options like the timeout interval. They have the
form <
code class="option">+keyword=value</
code>.
<
a name="id-1.8"></
a><
h2>ANYWHERE OPTIONS</
h2>
The <
code class="option">-f</
code> option makes <
span class="command"><
strong>mdig</
strong></
span>
operate in batch mode by reading a list of lookup requests to
process from the file <
em class="parameter"><
code>filename</
code></
em>. 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 <
span class="command"><
strong>mdig</
strong></
span> using the command-line interface.
The <
code class="option">-h</
code> causes <
span class="command"><
strong>mdig</
strong></
span> to
print the detailed help with the full list of options and exit.
The <
code class="option">-v</
code> causes <
span class="command"><
strong>mdig</
strong></
span> to
print the version number and exit.
<
a name="id-1.9"></
a><
h2>GLOBAL OPTIONS</
h2>
The <
code class="option">-4</
code> option forces <
span class="command"><
strong>mdig</
strong></
span> to
only use IPv4 query transport.
The <
code class="option">-6</
code> option forces <
span class="command"><
strong>mdig</
strong></
span> to
only use IPv6 query transport.
The <
code class="option">-b</
code> option sets the source IP address of the
query to <
em class="parameter"><
code>address</
code></
em>. 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
The <
code class="option">-p</
code> option is used when a non-standard port
<
em class="parameter"><
code>port#</
code></
em> is the port number
that <
span class="command"><
strong>mdig</
strong></
span> 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 global query options are:
<
div class="variablelist"><
dl class="variablelist">
<
dt><
span class="term"><
code class="option">+[no]additional</
code></
span></
dt>
Display [do not display] the additional section of a
reply. The default is to display it.
<
dt><
span class="term"><
code class="option">+[no]all</
code></
span></
dt>
Set or clear all display flags.
<
dt><
span class="term"><
code class="option">+[no]answer</
code></
span></
dt>
Display [do not display] the answer section of a
reply. The default is to display it.
<
dt><
span class="term"><
code class="option">+[no]authority</
code></
span></
dt>
Display [do not display] the authority section of a
reply. The default is to display it.
<
dt><
span class="term"><
code class="option">+[no]besteffort</
code></
span></
dt>
Attempt to display the contents of messages which are
malformed. The default is to not display malformed
<
dt><
span class="term"><
code class="option">+[no]cl</
code></
span></
dt>
Display [do not display] the CLASS when printing the
<
dt><
span class="term"><
code class="option">+[no]comments</
code></
span></
dt>
Toggle the display of comment lines in the output.
The default is to print comments.
<
dt><
span class="term"><
code class="option">+[no]continue</
code></
span></
dt>
Continue on errors (
e.g. timeouts).
<
dt><
span class="term"><
code class="option">+[no]crypto</
code></
span></
dt>
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 ]".
<
dt><
span class="term"><
code class="option">+dscp[=value]</
code></
span></
dt>
Set the DSCP code point to be used when sending the
query. Valid DSCP code points are in the range
[0..63]. By default no code point is explicitly set.
<
dt><
span class="term"><
code class="option">+[no]multiline</
code></
span></
dt>
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 <
span class="command"><
strong>mdig</
strong></
span>
<
dt><
span class="term"><
code class="option">+[no]question</
code></
span></
dt>
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.
<
dt><
span class="term"><
code class="option">+[no]rrcomments</
code></
span></
dt>
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.
<
dt><
span class="term"><
code class="option">+[no]short</
code></
span></
dt>
Provide a terse answer. The default is to print the
answer in a verbose form.
<
dt><
span class="term"><
code class="option">+split=W</
code></
span></
dt>
Split long hex- or base64-formatted fields in resource
records into chunks of <
em class="parameter"><
code>W</
code></
em>
characters (where <
em class="parameter"><
code>W</
code></
em> is rounded
up to the nearest multiple of 4).
<
em class="parameter"><
code>+nosplit</
code></
em> or
<
em class="parameter"><
code>+split=0</
code></
em> causes fields not to
be split at all. The default is 56 characters, or
44 characters when multiline mode is active.
<
dt><
span class="term"><
code class="option">+[no]tcp</
code></
span></
dt>
Use [do not use] TCP when querying name servers. The
default behavior is to use UDP.
<
dt><
span class="term"><
code class="option">+[no]ttlid</
code></
span></
dt>
Display [do not display] the TTL when printing the
<
dt><
span class="term"><
code class="option">+[no]ttlunits</
code></
span></
dt>
Display [do not display] the TTL in friendly human-readable
time units of "s", "m", "h", "d", and "w", representing
seconds, minutes, hours, days and weeks. Implies +ttlid.
<
dt><
span class="term"><
code class="option">+[no]vc</
code></
span></
dt>
Use [do not use] TCP when querying name servers. This
alternate syntax to <
em class="parameter"><
code>+[no]tcp</
code></
em>
is provided for backwards compatibility. The "vc"
stands for "virtual circuit".
<
a name="id-1.10"></
a><
h2>LOCAL OPTIONS</
h2>
The <
code class="option">-c</
code> option sets the query class to
<
em class="parameter"><
code>class</
code></
em>. It can be any valid query class
which is supported in BIND 9. The default query class is "IN".
The <
code class="option">-t</
code> option sets the query type to
<
em class="parameter"><
code>type</
code></
em>. It can be any valid query type
which is supported in BIND 9. The default query type is "A",
unless the <
code class="option">-x</
code> option is supplied to indicate
a reverse lookup with the "PTR" query type.
The <
code class="option">-i</
code> option sets the reverse domain for
Reverse lookups — mapping addresses to names — are
simplified by the <
code class="option">-x</
code> option.
<
em class="parameter"><
code>addr</
code></
em> is an IPv4
address in dotted-decimal notation, or a colon-delimited IPv6 address.
<
span class="command"><
strong>mdig</
strong></
span> automatically performs a lookup for a
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 <
code class="option">-i</
code> option.
The local query options are:
<
div class="variablelist"><
dl class="variablelist">
<
dt><
span class="term"><
code class="option">+[no]aaflag</
code></
span></
dt>
A synonym for <
em class="parameter"><
code>+[no]aaonly</
code></
em>.
<
dt><
span class="term"><
code class="option">+[no]aaonly</
code></
span></
dt>
Sets the "aa" flag in the query.
<
dt><
span class="term"><
code class="option">+[no]adflag</
code></
span></
dt>
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
<
dt><
span class="term"><
code class="option">+bufsize=B</
code></
span></
dt>
Set the UDP message buffer size advertised using EDNS0
to <
em class="parameter"><
code>B</
code></
em> 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
<
dt><
span class="term"><
code class="option">+[no]cdflag</
code></
span></
dt>
Set [do not set] the CD (checking disabled) bit in
the query. This requests the server to not perform
DNSSEC validation of responses.
<
dt><
span class="term"><
code class="option">+[no]cookie[<
span class="optional">=####</
span>]</
code></
span></
dt>
Send a COOKIE EDNS option, with optional value.
Replaying a COOKIE from a previous response will allow
the server to identify a previous client. The default
is <
code class="option">+nocookie</
code>.
<
dt><
span class="term"><
code class="option">+[no]dnssec</
code></
span></
dt>
Requests DNSSEC records be sent by setting the DNSSEC
OK bit (DO) in the OPT record in the additional section
<
dt><
span class="term"><
code class="option">+[no]edns[=#]</
code></
span></
dt>
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. <
code class="option">+noedns</
code>
clears the remembered EDNS version. EDNS is set to
<
dt><
span class="term"><
code class="option">+[no]ednsflags[=#]</
code></
span></
dt>
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.
<
dt><
span class="term"><
code class="option">+[no]ednsopt[=code[:value]]</
code></
span></
dt>
Specify EDNS option with code point <
code class="option">code</
code>
and optionally payload of <
code class="option">value</
code> as a
hexadecimal string. <
code class="option">+noednsopt</
code>
clears the EDNS options to be sent.
<
dt><
span class="term"><
code class="option">+[no]expire</
code></
span></
dt>
Send an EDNS Expire option.
<
dt><
span class="term"><
code class="option">+[no]nsid</
code></
span></
dt>
Include an EDNS name server ID request when sending
<
dt><
span class="term"><
code class="option">+[no]recurse</
code></
span></
dt>
Toggle the setting of the RD (recursion desired) bit
in the query. This bit is set by default, which means
<
span class="command"><
strong>mdig</
strong></
span> normally sends recursive
<
dt><
span class="term"><
code class="option">+retry=T</
code></
span></
dt>
Sets the number of times to retry UDP queries to
server to <
em class="parameter"><
code>T</
code></
em> instead of the
default, 2. Unlike <
em class="parameter"><
code>+tries</
code></
em>,
this does not include the initial query.
<
dt><
span class="term"><
code class="option">+[no]subnet=addr[/prefix-length]</
code></
span></
dt>
Send (don't send) an EDNS Client Subnet option with the
specified IP address or network prefix.
<
span class="command"><
strong>mdig +subnet=0.0.0.0/0</
strong></
span>, or simply
<
span class="command"><
strong>mdig +subnet=0</
strong></
span> 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
<
span class="emphasis"><
em>not</
em></
span> be used when resolving
<
dt><
span class="term"><
code class="option">+timeout=T</
code></
span></
dt>
Sets the timeout for a query to
<
em class="parameter"><
code>T</
code></
em> seconds. The default
timeout is 5 seconds for UDP transport and 10 for TCP.
An attempt to set <
em class="parameter"><
code>T</
code></
em> to less
in a query timeout of 1 second being applied.
<
dt><
span class="term"><
code class="option">+tries=T</
code></
span></
dt>
Sets the number of times to try UDP queries to server
to <
em class="parameter"><
code>T</
code></
em> instead of the default,
3. If <
em class="parameter"><
code>T</
code></
em> is less than or equal
to zero, the number of tries is silently rounded up
<
dt><
span class="term"><
code class="option">+udptimeout=T</
code></
span></
dt>
Sets the timeout between UDP query retries.
<
dt><
span class="term"><
code class="option">+[no]unknownformat</
code></
span></
dt>
Print all RDATA in unknown RR type presentation format
(RFC 3597). The default is to print RDATA for known types
in the type's presentation format.
<
dt><
span class="term"><
code class="option">+[no]zflag</
code></
span></
dt>
Set [do not set] the last unassigned DNS header flag in a
DNS query. This flag is off by default.
<
a name="id-1.11"></
a><
h2>SEE ALSO</
h2>
<
p><
span class="citerefentry">
<
span class="refentrytitle">dig</
span>(1)
<
em class="citetitle">RFC1035</
em>.