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<div class="refentry">
<a name="man.delv"></a><div class="titlepage"></div>

<div class="refnamediv">
<h2>Name</h2>

 delv
 &#8212; DNS lookup and validation utility
 
</div>

<div class="refsynopsisdiv">
<h2>Synopsis</h2>
 <div class="cmdsynopsis">
 <code class="command">delv</code> 
 [@server]
 [
	[<code class="option">-4</code>]
	 | [<code class="option">-6</code>]
 ]
 [<code class="option">-a <code>anchor-file</code></code>]
 [<code class="option">-b <code>address</code></code>]
 [<code class="option">-c <code>class</code></code>]
 [<code class="option">-d <code>level</code></code>]
 [<code class="option">-i</code>]
 [<code class="option">-m</code>]
 [<code class="option">-p <code>port#</code></code>]
 [<code class="option">-q <code>name</code></code>]
 [<code class="option">-t <code>type</code></code>]
 [<code class="option">-x <code>addr</code></code>]
 [name]
 [type]
 [class]
 [queryopt...]
 </div>

<div class="cmdsynopsis">
 <code class="command">delv</code> 
 [queryopt...]
 [query...]
 </div>
 </div>

<div class="refsection">
<a name="id-1.14.5.7"></a><h2>DESCRIPTION</h2>

delv
 is a tool for sending
 DNS queries and validating the results, using the same internal
 resolver and validator logic as named.
 
 
 delv 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.
 
 
 By default, responses are validated using built-in DNSSEC trust
 anchor for the root zone ("."). Records returned by
 delv 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 delv 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.
 
 
 Unless it is told to query a specific name server,
 delv will try each of the servers listed in
 <code class="filename">/etc/resolv.conf</code>. If no usable server
 addresses are found, delv will send
 queries to the localhost addresses (127.0.0.1 for IPv4, ::1
 for IPv6).
 
 
 When no command line arguments or options are given,
 delv will perform an NS query for "."
 (the root zone).
 
 </div>

<div class="refsection">
<a name="id-1.14.5.8"></a><h2>SIMPLE USAGE</h2>

A typical invocation of delv looks like:
 
<pre class="programlisting"> delv @server name type </pre>

 where:

<div class="variablelist"><dl class="variablelist">
<dt><code class="constant">server</code></dt>
<dd>
	 
	 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
	 <code>server</code> argument is a hostname,
	 delv resolves that name before
	 querying that name server (note, however, that this
	 initial lookup is not validated
	 by DNSSEC).
	 
	 
	 If no <code>server</code> argument is
	 provided, delv 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,
	 delv will send queries to
	 the localhost addresses (127.0.0.1 for IPv4,
	 ::1 for IPv6).
	 
	 </dd>
<dt><code class="constant">name</code></dt>
<dd>
	 
	 is the domain name to be looked up.
	 
	 </dd>
<dt><code class="constant">type</code></dt>
<dd>
	 
	 indicates what type of query is required &#8212;
	 ANY, A, MX, etc.
	 <code>type</code> can be any valid query
	 type. If no
	 <code>type</code> argument is supplied,
	 delv will perform a lookup for an
	 A record.
	 
	 </dd>
</dl></div>

</div>

<div class="refsection">
<a name="id-1.14.5.9"></a><h2>OPTIONS</h2>

<div class="variablelist"><dl class="variablelist">
<dt>-a <code>anchor-file</code></dt>
<dd>
	 
	 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 (".").
	 
	 
	 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.
	 
	 
	 Note: When reading the trust anchor file,
	 delv 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
	 initial key that is trusted; RFC 5011
	 key management is not supported. delv
	 will not consult the managed-keys database maintained by
	 named. 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 delv.
	 
	</dd>
<dt>-b <code>address</code></dt>
<dd>
	 
	 Sets the source IP address of the query to
	 <code>address</code>. 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
	 "#&lt;port&gt;"
	 
	</dd>
<dt>-c <code>class</code></dt>
<dd>
	 
	 Sets the query class for the requested data. Currently,
	 only class "IN" is supported in delv
	 and any other value is ignored.
	 
	</dd>
<dt>-d <code>level</code></dt>
<dd>
	 
	 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 delv 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.
	 
	</dd>
<dt>-h</dt>
<dd>
	 
	 Display the delv help usage output and exit.
	 
	</dd>
<dt>-i</dt>
<dd>
	 
	 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 delv to time out. When it
	 is necessary to examine invalid data to debug a DNSSEC
	 problem, use dig +cd.)
	 
	</dd>
<dt>-m</dt>
<dd>
	 
	 Enables memory usage debugging.
	 
	</dd>
<dt>-p <code>port#</code></dt>
<dd>
	 
	 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.
	 
	</dd>
<dt>-q <code>name</code></dt>
<dd>
	 
	 Sets the query name to <code>name</code>.
	 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).
	 
	</dd>
<dt>-t <code>type</code></dt>
<dd>
	 
	 Sets the query type to <code>type</code>, 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.
	 
	 
	 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".
	 
	</dd>
<dt>-v</dt>
<dd>
	 
	 Print the delv version and exit.
	 
	</dd>
<dt>-x <code>addr</code></dt>
<dd>
	 
	 Performs a reverse lookup, mapping an addresses to
	 a name. <code>addr</code> 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 <code>name</code> or <code>type</code>
	 arguments. delv 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.
	 
	</dd>
<dt>-4</dt>
<dd>
	 
	 Forces delv to only use IPv4.
	 
	</dd>
<dt>-6</dt>
<dd>
	 
	 Forces delv to only use IPv6.
	 
	</dd>
</dl></div>
 </div>

<div class="refsection">
<a name="id-1.14.5.10"></a><h2>QUERY OPTIONS</h2>

delv
 provides a number of query options which affect the way results are
 displayed, and in some cases the way lookups are performed.

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:

<div class="variablelist"><dl class="variablelist">
<dt><code class="option">+[no]cdflag</code></dt>
<dd>
	 
	 Controls whether to set the CD (checking disabled) bit in
	 queries sent by delv. 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 delv can then
	 validate internally and report the errors in detail.
	 
	 </dd>
<dt><code class="option">+[no]class</code></dt>
<dd>
	 
	 Controls whether to display the CLASS when printing
	 a record. The default is to display the CLASS.
	 
	 </dd>
<dt><code class="option">+[no]ttl</code></dt>
<dd>
	 
	 Controls whether to display the TTL when printing
	 a record. The default is to display the TTL.
	 
	 </dd>
<dt><code class="option">+[no]rtrace</code></dt>
<dd>
	 
	 Toggle resolver fetch logging. This reports the
	 name and type of each query sent by delv
	 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.
	 
	 
	 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).
	 
	 </dd>
<dt><code class="option">+[no]mtrace</code></dt>
<dd>
	 
	 Toggle message logging. This produces a detailed dump of
	 the responses received by delv in the
	 process of carrying out the resolution and validation process.
	 
	 
	 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).
	 
	 </dd>
<dt><code class="option">+[no]vtrace</code></dt>
<dd>
	 
	 Toggle validation logging. This shows the internal
	 process of the validator as it determines whether an
	 answer is validly signed, unsigned, or invalid.
	 
	 
	 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).
	 
	 </dd>
<dt><code class="option">+[no]short</code></dt>
<dd>
	 
	 Provide a terse answer. The default is to print the answer in a
	 verbose form.
	 
	 </dd>
<dt><code class="option">+[no]comments</code></dt>
<dd>
	 
	 Toggle the display of comment lines in the output. The default
	 is to print comments.
	 
	 </dd>
<dt><code class="option">+[no]rrcomments</code></dt>
<dd>
	 
	 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.
	 
	 </dd>
<dt><code class="option">+[no]crypto</code></dt>
<dd>
	 
	 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 ]".
	 
	 </dd>
<dt><code class="option">+[no]trust</code></dt>
<dd>
	 
	 Controls whether to display the trust level when printing
	 a record. The default is to display the trust level.
	 
	 </dd>
<dt><code class="option">+[no]split[=W]</code></dt>
<dd>
	 
	 Split long hex- or base64-formatted fields in resource
	 records into chunks of <code>W</code> characters
	 (where <code>W</code> is rounded up to the nearest
	 multiple of 4).
	 <code>+nosplit</code> or
	 <code>+split=0</code> causes fields not to be
	 split at all. The default is 56 characters, or 44 characters
	 when multiline mode is active.
	 
	 </dd>
<dt><code class="option">+[no]all</code></dt>
<dd>
	 
	 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.
	 
	 </dd>
<dt><code class="option">+[no]multiline</code></dt>
<dd>
	 
	 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 delv
	 output.
	 
	 </dd>
<dt><code class="option">+[no]dnssec</code></dt>
<dd>
	 
	 Indicates whether to display RRSIG records in the
	 delv output. The default is to
	 do so. Note that (unlike in dig)
	 this does not 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>.
	 
	 </dd>
<dt><code class="option">+[no]root[=ROOT]</code></dt>
<dd>
	 
	 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.
	 
	 </dd>
<dt><code class="option">+[no]dlv[=DLV]</code></dt>
<dd>
	 
	 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.
	 
	 </dd>
<dt><code class="option">+[no]tcp</code></dt>
<dd>
	 
	 Controls whether to use TCP when sending queries.
	 The default is to use UDP unless a truncated
	 response has been received.
	 
	 </dd>
<dt><code class="option">+[no]unknownformat</code></dt>
<dd>
	 
	 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.
	 
	 </dd>
</dl></div>

</div>

<div class="refsection">
<a name="id-1.14.5.11"></a><h2>FILES</h2>

<code class="filename">/etc/bind.keys</code>
 <code class="filename">/etc/resolv.conf</code>
 </div>

dig(1)
 ,
 
	named(8)
 ,
 RFC4034,
 RFC4035,
 RFC4431,
 RFC5074,
 RFC5155.
 
 </div>

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