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<div class="refentry">
<a name="man.delv"></a><div class="titlepage"></div>
<div class="refnamediv">
<h2>Name</h2>
<p>
delv
— DNS lookup and validation utility
</p>
</div>
<div class="refsynopsisdiv">
<h2>Synopsis</h2>
<div class="cmdsynopsis"><p>
<code class="command">delv</code>
[@server]
[
[<code class="option">-4</code>]
| [<code class="option">-6</code>]
]
[<code class="option">-a <em class="replaceable"><code>anchor-file</code></em></code>]
[<code class="option">-b <em class="replaceable"><code>address</code></em></code>]
[<code class="option">-c <em class="replaceable"><code>class</code></em></code>]
[<code class="option">-d <em class="replaceable"><code>level</code></em></code>]
[<code class="option">-i</code>]
[<code class="option">-m</code>]
[<code class="option">-p <em class="replaceable"><code>port#</code></em></code>]
[<code class="option">-q <em class="replaceable"><code>name</code></em></code>]
[<code class="option">-t <em class="replaceable"><code>type</code></em></code>]
[<code class="option">-x <em class="replaceable"><code>addr</code></em></code>]
[name]
[type]
[class]
[queryopt...]
</p></div>
<div class="cmdsynopsis"><p>
<code class="command">delv</code>
[<code class="option">-h</code>]
</p></div>
<div class="cmdsynopsis"><p>
<code class="command">delv</code>
[<code class="option">-v</code>]
</p></div>
<div class="cmdsynopsis"><p>
<code class="command">delv</code>
[queryopt...]
[query...]
</p></div>
</div>
<div class="refsection">
<a name="id-1.14.5.7"></a><h2>DESCRIPTION</h2>
<p><span class="command"><strong>delv</strong></span>
is a tool for sending
DNS queries and validating the results, using the same internal
resolver and validator logic as <span class="command"><strong>named</strong></span>.
</p>
<p>
<span class="command"><strong>delv</strong></span> will send to a specified name server all
queries needed to fetch and validate the requested data; this
includes the original requested query, subsequent queries to follow
CNAME or DNAME chains, and queries for DNSKEY, DS and DLV records
to establish a chain of trust for DNSSEC validation.
It does not perform iterative resolution, but simulates the
behavior of a name server configured for DNSSEC validating and
forwarding.
</p>
<p>
By default, responses are validated using built-in DNSSEC trust
anchor for the root zone ("."). Records returned by
<span class="command"><strong>delv</strong></span> are either fully validated or
were not signed. If validation fails, an explanation of
the failure is included in the output; the validation process
can be traced in detail. Because <span class="command"><strong>delv</strong></span> does
not rely on an external server to carry out validation, it can
be used to check the validity of DNS responses in environments
where local name servers may not be trustworthy.
</p>
<p>
Unless it is told to query a specific name server,
<span class="command"><strong>delv</strong></span> will try each of the servers listed in
<code class="filename">/etc/resolv.conf</code>. If no usable server
addresses are found, <span class="command"><strong>delv</strong></span> will send
queries to the localhost addresses (127.0.0.1 for IPv4, ::1
for IPv6).
</p>
<p>
When no command line arguments or options are given,
<span class="command"><strong>delv</strong></span> will perform an NS query for "."
(the root zone).
</p>
</div>
<div class="refsection">
<a name="id-1.14.5.8"></a><h2>SIMPLE USAGE</h2>
<p>
A typical invocation of <span class="command"><strong>delv</strong></span> looks like:
</p>
<pre class="programlisting"> delv @server name type </pre>
<p>
where:
</p>
<div class="variablelist"><dl class="variablelist">
<dt><span class="term"><code class="constant">server</code></span></dt>
<dd>
<p>
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
<em class="parameter"><code>server</code></em> argument is a hostname,
<span class="command"><strong>delv</strong></span> resolves that name before
querying that name server (note, however, that this
initial lookup is <span class="emphasis"><em>not</em></span> validated
by DNSSEC).
</p>
<p>
If no <em class="parameter"><code>server</code></em> argument is
provided, <span class="command"><strong>delv</strong></span> consults
<code class="filename">/etc/resolv.conf</code>; if an
address is found there, it queries the name server at
that address. If either of the <code class="option">-4</code> or
<code class="option">-6</code> options are in use, then
only addresses for the corresponding transport
will be tried. If no usable addresses are found,
<span class="command"><strong>delv</strong></span> will send queries to
the localhost addresses (127.0.0.1 for IPv4,
::1 for IPv6).
</p>
</dd>
<dt><span class="term"><code class="constant">name</code></span></dt>
<dd>
<p>
is the domain name to be looked up.
</p>
</dd>
<dt><span class="term"><code class="constant">type</code></span></dt>
<dd>
<p>
indicates what type of query is required —
ANY, A, MX, etc.
<em class="parameter"><code>type</code></em> can be any valid query
type. If no
<em class="parameter"><code>type</code></em> argument is supplied,
<span class="command"><strong>delv</strong></span> will perform a lookup for an
A record.
</p>
</dd>
</dl></div>
<p>
</p>
</div>
<div class="refsection">
<a name="id-1.14.5.9"></a><h2>OPTIONS</h2>
<div class="variablelist"><dl class="variablelist">
<dt><span class="term">-a <em class="replaceable"><code>anchor-file</code></em></span></dt>
<dd>
<p>
Specifies a file from which to read DNSSEC trust anchors.
The default is <code class="filename">/etc/bind.keys</code>, which
is included with <acronym class="acronym">BIND</acronym> 9 and contains
one or more trust anchors for the root zone (".").
</p>
<p>
Keys that do not match the root zone name are ignored.
An alternate key name can be specified using the
<code class="option">+root=NAME</code> options. DNSSEC Lookaside
Validation can also be turned on by using the
<code class="option">+dlv=NAME</code> to specify the name of a
zone containing DLV records.
</p>
<p>
Note: When reading the trust anchor file,
<span class="command"><strong>delv</strong></span> treats <code class="option">managed-keys</code>
statements and <code class="option">trusted-keys</code> statements
identically. That is, for a managed key, it is the
<span class="emphasis"><em>initial</em></span> key that is trusted; RFC 5011
key management is not supported. <span class="command"><strong>delv</strong></span>
will not consult the managed-keys database maintained by
<span class="command"><strong>named</strong></span>. This means that if either of the
keys in <code class="filename">/etc/bind.keys</code> is revoked
and rolled over, it will be necessary to update
<code class="filename">/etc/bind.keys</code> to use DNSSEC
validation in <span class="command"><strong>delv</strong></span>.
</p>
</dd>
<dt><span class="term">-b <em class="replaceable"><code>address</code></em></span></dt>
<dd>
<p>
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 source port may be specified by appending
"#<port>"
</p>
</dd>
<dt><span class="term">-c <em class="replaceable"><code>class</code></em></span></dt>
<dd>
<p>
Sets the query class for the requested data. Currently,
only class "IN" is supported in <span class="command"><strong>delv</strong></span>
and any other value is ignored.
</p>
</dd>
<dt><span class="term">-d <em class="replaceable"><code>level</code></em></span></dt>
<dd>
<p>
Set the systemwide debug level to <code class="option">level</code>.
The allowed range is from 0 to 99.
The default is 0 (no debugging).
Debugging traces from <span class="command"><strong>delv</strong></span> become
more verbose as the debug level increases.
See the <code class="option">+mtrace</code>, <code class="option">+rtrace</code>,
and <code class="option">+vtrace</code> options below for additional
debugging details.
</p>
</dd>
<dt><span class="term">-h</span></dt>
<dd>
<p>
Display the <span class="command"><strong>delv</strong></span> help usage output and exit.
</p>
</dd>
<dt><span class="term">-i</span></dt>
<dd>
<p>
Insecure mode. This disables internal DNSSEC validation.
(Note, however, this does not set the CD bit on upstream
queries. If the server being queried is performing DNSSEC
validation, then it will not return invalid data; this
can cause <span class="command"><strong>delv</strong></span> to time out. When it
is necessary to examine invalid data to debug a DNSSEC
problem, use <span class="command"><strong>dig +cd</strong></span>.)
</p>
</dd>
<dt><span class="term">-m</span></dt>
<dd>
<p>
Enables memory usage debugging.
</p>
</dd>
<dt><span class="term">-p <em class="replaceable"><code>port#</code></em></span></dt>
<dd>
<p>
Specifies a destination port to use for queries instead of
the standard DNS port number 53. This option would be used
with a name server that has been configured to listen
for queries on a non-standard port number.
</p>
</dd>
<dt><span class="term">-q <em class="replaceable"><code>name</code></em></span></dt>
<dd>
<p>
Sets the query name to <em class="parameter"><code>name</code></em>.
While the query name can be specified without using the
<code class="option">-q</code>, it is sometimes necessary to disambiguate
names from types or classes (for example, when looking up the
name "ns", which could be misinterpreted as the type NS,
or "ch", which could be misinterpreted as class CH).
</p>
</dd>
<dt><span class="term">-t <em class="replaceable"><code>type</code></em></span></dt>
<dd>
<p>
Sets the query type to <em class="parameter"><code>type</code></em>, which
can be any valid query type supported in BIND 9 except
for zone transfer types AXFR and IXFR. As with
<code class="option">-q</code>, this is useful to distinguish
query name type or class when they are ambiguous.
it is sometimes necessary to disambiguate names from types.
</p>
<p>
The default query type is "A", unless the <code class="option">-x</code>
option is supplied to indicate a reverse lookup, in which case
it is "PTR".
</p>
</dd>
<dt><span class="term">-v</span></dt>
<dd>
<p>
Print the <span class="command"><strong>delv</strong></span> version and exit.
</p>
</dd>
<dt><span class="term">-x <em class="replaceable"><code>addr</code></em></span></dt>
<dd>
<p>
Performs a reverse lookup, mapping an addresses to
a name. <em class="parameter"><code>addr</code></em> is an IPv4 address in
dotted-decimal notation, or a colon-delimited IPv6 address.
When <code class="option">-x</code> is used, there is no need to provide
the <em class="parameter"><code>name</code></em> or <em class="parameter"><code>type</code></em>
arguments. <span class="command"><strong>delv</strong></span> automatically performs a
lookup for a name like <code class="literal">11.12.13.10.in-addr.arpa</code>
and sets the query type to PTR. IPv6 addresses are looked up
using nibble format under the IP6.ARPA domain.
</p>
</dd>
<dt><span class="term">-4</span></dt>
<dd>
<p>
Forces <span class="command"><strong>delv</strong></span> to only use IPv4.
</p>
</dd>
<dt><span class="term">-6</span></dt>
<dd>
<p>
Forces <span class="command"><strong>delv</strong></span> to only use IPv6.
</p>
</dd>
</dl></div>
</div>
<div class="refsection">
<a name="id-1.14.5.10"></a><h2>QUERY OPTIONS</h2>
<p><span class="command"><strong>delv</strong></span>
provides a number of query options which affect the way results are
displayed, and in some cases the way lookups are performed.
</p>
<p>
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>.
The query options are:
</p>
<div class="variablelist"><dl class="variablelist">
<dt><span class="term"><code class="option">+[no]cdflag</code></span></dt>
<dd>
<p>
Controls whether to set the CD (checking disabled) bit in
queries sent by <span class="command"><strong>delv</strong></span>. This may be useful
when troubleshooting DNSSEC problems from behind a validating
resolver. A validating resolver will block invalid responses,
making it difficult to retrieve them for analysis. Setting
the CD flag on queries will cause the resolver to return
invalid responses, which <span class="command"><strong>delv</strong></span> can then
validate internally and report the errors in detail.
</p>
</dd>
<dt><span class="term"><code class="option">+[no]class</code></span></dt>
<dd>
<p>
Controls whether to display the CLASS when printing
a record. The default is to display the CLASS.
</p>
</dd>
<dt><span class="term"><code class="option">+[no]ttl</code></span></dt>
<dd>
<p>
Controls whether to display the TTL when printing
a record. The default is to display the TTL.
</p>
</dd>
<dt><span class="term"><code class="option">+[no]rtrace</code></span></dt>
<dd>
<p>
Toggle resolver fetch logging. This reports the
name and type of each query sent by <span class="command"><strong>delv</strong></span>
in the process of carrying out the resolution and validation
process: this includes including the original query and
all subsequent queries to follow CNAMEs and to establish a
chain of trust for DNSSEC validation.
</p>
<p>
This is equivalent to setting the debug level to 1 in
the "resolver" logging category. Setting the systemwide
debug level to 1 using the <code class="option">-d</code> option will
product the same output (but will affect other logging
categories as well).
</p>
</dd>
<dt><span class="term"><code class="option">+[no]mtrace</code></span></dt>
<dd>
<p>
Toggle message logging. This produces a detailed dump of
the responses received by <span class="command"><strong>delv</strong></span> in the
process of carrying out the resolution and validation process.
</p>
<p>
This is equivalent to setting the debug level to 10
for the "packets" module of the "resolver" logging
category. Setting the systemwide debug level to 10 using
the <code class="option">-d</code> option will produce the same output
(but will affect other logging categories as well).
</p>
</dd>
<dt><span class="term"><code class="option">+[no]vtrace</code></span></dt>
<dd>
<p>
Toggle validation logging. This shows the internal
process of the validator as it determines whether an
answer is validly signed, unsigned, or invalid.
</p>
<p>
This is equivalent to setting the debug level to 3
for the "validator" module of the "dnssec" logging
category. Setting the systemwide debug level to 3 using
the <code class="option">-d</code> option will produce the same output
(but will affect other logging categories as well).
</p>
</dd>
<dt><span class="term"><code class="option">+[no]short</code></span></dt>
<dd>
<p>
Provide a terse answer. The default is to print the answer in a
verbose form.
</p>
</dd>
<dt><span class="term"><code class="option">+[no]comments</code></span></dt>
<dd>
<p>
Toggle the display of comment lines in the output. The default
is to print comments.
</p>
</dd>
<dt><span class="term"><code class="option">+[no]rrcomments</code></span></dt>
<dd>
<p>
Toggle the display of per-record comments in the output (for
example, human-readable key information about DNSKEY records).
The default is to print per-record comments.
</p>
</dd>
<dt><span class="term"><code class="option">+[no]crypto</code></span></dt>
<dd>
<p>
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 ]".
</p>
</dd>
<dt><span class="term"><code class="option">+[no]trust</code></span></dt>
<dd>
<p>
Controls whether to display the trust level when printing
a record. The default is to display the trust level.
</p>
</dd>
<dt><span class="term"><code class="option">+[no]split[=W]</code></span></dt>
<dd>
<p>
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.
</p>
</dd>
<dt><span class="term"><code class="option">+[no]all</code></span></dt>
<dd>
<p>
Set or clear the display options
<code class="option">+[no]comments</code>,
<code class="option">+[no]rrcomments</code>, and
<code class="option">+[no]trust</code> as a group.
</p>
</dd>
<dt><span class="term"><code class="option">+[no]multiline</code></span></dt>
<dd>
<p>
Print long records (such as RRSIG, DNSKEY, and 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>delv</strong></span>
output.
</p>
</dd>
<dt><span class="term"><code class="option">+[no]dnssec</code></span></dt>
<dd>
<p>
Indicates whether to display RRSIG records in the
<span class="command"><strong>delv</strong></span> output. The default is to
do so. Note that (unlike in <span class="command"><strong>dig</strong></span>)
this does <span class="emphasis"><em>not</em></span> control whether to
request DNSSEC records or whether to validate them.
DNSSEC records are always requested, and validation
will always occur unless suppressed by the use of
<code class="option">-i</code> or <code class="option">+noroot</code> and
<code class="option">+nodlv</code>.
</p>
</dd>
<dt><span class="term"><code class="option">+[no]root[=ROOT]</code></span></dt>
<dd>
<p>
Indicates whether to perform conventional (non-lookaside)
DNSSEC validation, and if so, specifies the
name of a trust anchor. The default is to validate using
a trust anchor of "." (the root zone), for which there is
a built-in key. If specifying a different trust anchor,
then <code class="option">-a</code> must be used to specify a file
containing the key.
</p>
</dd>
<dt><span class="term"><code class="option">+[no]dlv[=DLV]</code></span></dt>
<dd>
<p>
Indicates whether to perform DNSSEC lookaside validation,
and if so, specifies the name of the DLV trust anchor.
The <code class="option">-a</code> option must also be used to specify
a file containing the DLV key.
</p>
</dd>
<dt><span class="term"><code class="option">+[no]tcp</code></span></dt>
<dd>
<p>
Controls whether to use TCP when sending queries.
The default is to use UDP unless a truncated
response has been received.
</p>
</dd>
<dt><span class="term"><code class="option">+[no]unknownformat</code></span></dt>
<dd>
<p>
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.
</p>
</dd>
</dl></div>
<p>
</p>
</div>
<div class="refsection">
<a name="id-1.14.5.11"></a><h2>FILES</h2>
<p><code class="filename">/etc/bind.keys</code></p>
<p><code class="filename">/etc/resolv.conf</code></p>
</div>
<div class="refsection">
<a name="id-1.14.5.12"></a><h2>SEE ALSO</h2>
<p><span class="citerefentry">
<span class="refentrytitle">dig</span>(1)
</span>,
<span class="citerefentry">
<span class="refentrytitle">named</span>(8)
</span>,
<em class="citetitle">RFC4034</em>,
<em class="citetitle">RFC4035</em>,
<em class="citetitle">RFC4431</em>,
<em class="citetitle">RFC5074</em>,
<em class="citetitle">RFC5155</em>.
</p>
</div>
</div>
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