<!DOCTYPE book [

<!ENTITY mdash "&#8212;">]>

<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="man.delv">

<info>

<date>2014-04-23</date>

</info>

<refentryinfo>

<corpname>ISC</corpname>

<corpauthor>Internet Systems Consortium, Inc.</corpauthor>

</refentryinfo>

<refmeta>

<refentrytitle>delv</refentrytitle>

<manvolnum>1</manvolnum>

<refmiscinfo>BIND9</refmiscinfo>

</refmeta>

<refnamediv>

<refname>delv</refname>

<refpurpose>DNS lookup and validation utility</refpurpose>

</refnamediv>

<docinfo>

<copyright>

<year>2014</year>

<year>2015</year>

<holder>Internet Systems Consortium, Inc. ("ISC")</holder>

</copyright>

</docinfo>

<refsynopsisdiv>

<cmdsynopsis sepchar=" ">

<command>delv</command>

<arg choice="opt" rep="norepeat">@server</arg>

<arg choice="opt" rep="norepeat"><option>-4</option></arg>

<arg choice="opt" rep="norepeat"><option>-6</option></arg>

<arg choice="opt" rep="norepeat"><option>-a <replaceable class="parameter">anchor-file</replaceable></option></arg>

<arg choice="opt" rep="norepeat"><option>-b <replaceable class="parameter">address</replaceable></option></arg>

<arg choice="opt" rep="norepeat"><option>-c <replaceable class="parameter">class</replaceable></option></arg>

<arg choice="opt" rep="norepeat"><option>-d <replaceable class="parameter">level</replaceable></option></arg>

<arg choice="opt" rep="norepeat"><option>-i</option></arg>

<arg choice="opt" rep="norepeat"><option>-m</option></arg>

<arg choice="opt" rep="norepeat"><option>-p <replaceable class="parameter">port#</replaceable></option></arg>

<arg choice="opt" rep="norepeat"><option>-q <replaceable class="parameter">name</replaceable></option></arg>

<arg choice="opt" rep="norepeat"><option>-t <replaceable class="parameter">type</replaceable></option></arg>

<arg choice="opt" rep="norepeat"><option>-x <replaceable class="parameter">addr</replaceable></option></arg>

<arg choice="opt" rep="norepeat">name</arg>

<arg choice="opt" rep="norepeat">type</arg>

<arg choice="opt" rep="norepeat">class</arg>

<arg choice="opt" rep="repeat">queryopt</arg>

</cmdsynopsis>

<cmdsynopsis sepchar=" ">

<command>delv</command>

<arg choice="opt" rep="norepeat"><option>-h</option></arg>

</cmdsynopsis>

<cmdsynopsis sepchar=" ">

<command>delv</command>

<arg choice="opt" rep="norepeat"><option>-v</option></arg>

</cmdsynopsis>

<cmdsynopsis sepchar=" ">

<command>delv</command>

<arg choice="opt" rep="repeat">queryopt</arg>

<arg choice="opt" rep="repeat">query</arg>

</cmdsynopsis>

</refsynopsisdiv>

<refsection><info><title>DESCRIPTION</title></info>

<para><command>delv</command>

(Domain Entity Lookup &amp; Validation) is a tool for sending

DNS queries and validating the results, using the same internal

resolver and validator logic as <command>named</command>.

</para>

<para>

<command>delv</command> 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.

</para>

<para>

By default, responses are validated using built-in DNSSEC trust

anchors for the root zone (".") and for the ISC DNSSEC lookaside

validation zone ("dlv.isc.org"). Records returned by

<command>delv</command> 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 <command>delv</command> 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.

</para>

<para>

Unless it is told to query a specific name server,

<command>delv</command> will try each of the servers listed in

<filename>/etc/resolv.conf</filename>. If no usable server

addresses are found, <command>delv</command> will send

queries to the localhost addresses (127.0.0.1 for IPv4, ::1

for IPv6).

</para>

<para>

When no command line arguments or options are given,

<command>delv</command> will perform an NS query for "."

(the root zone).

</para>

</refsection>

<refsection><info><title>SIMPLE USAGE</title></info>

<para>

A typical invocation of <command>delv</command> looks like:

<programlisting> delv @server name type </programlisting>

where:

<variablelist>

<varlistentry>

<term><constant>server</constant></term>

<listitem>

<para>

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

<parameter>server</parameter> argument is a hostname,

<command>delv</command> resolves that name before

querying that name server (note, however, that this

initial lookup is <emphasis>not</emphasis> validated

by DNSSEC).

</para>

<para>

If no <parameter>server</parameter> argument is

provided, <command>delv</command> consults

<filename>/etc/resolv.conf</filename>; if an

address is found there, it queries the name server at

that address. If either of the <option>-4</option> or

<option>-6</option> options are in use, then

only addresses for the corresponding transport

will be tried. If no usable addresses are found,

<command>delv</command> will send queries to

the localhost addresses (127.0.0.1 for IPv4,

::1 for IPv6).

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><constant>name</constant></term>

<listitem>

<para>

is the domain name to be looked up.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><constant>type</constant></term>

<listitem>

<para>

indicates what type of query is required &mdash;

ANY, A, MX, etc.

<parameter>type</parameter> can be any valid query

type. If no

<parameter>type</parameter> argument is supplied,

<command>delv</command> will perform a lookup for an

A record.

</para>

</listitem>

</varlistentry>

</variablelist>

</para>

</refsection>

<refsection><info><title>OPTIONS</title></info>

<variablelist>

<varlistentry>

<term>-a <replaceable class="parameter">anchor-file</replaceable></term>

<listitem>

<para>

Specifies a file from which to read DNSSEC trust anchors.

The default is <filename>/etc/bind.keys</filename>, which

is included with <acronym>BIND</acronym> 9 and contains

trust anchors for the root zone (".") and for the ISC

DNSSEC lookaside validation zone ("dlv.isc.org").

</para>

<para>

Keys that do not match the root or DLV trust-anchor

names are ignored; these key names can be overridden

using the <option>+dlv=NAME</option> or

<option>+root=NAME</option> options.

</para>

<para>

Note: When reading the trust anchor file,

<command>delv</command> treats <option>managed-keys</option>

statements and <option>trusted-keys</option> statements

identically. That is, for a managed key, it is the

<emphasis>initial</emphasis> key that is trusted; RFC 5011

key management is not supported. <command>delv</command>

will not consult the managed-keys database maintained by

<command>named</command>. This means that if either of the

keys in <filename>/etc/bind.keys</filename> is revoked

and rolled over, it will be necessary to update

<filename>/etc/bind.keys</filename> to use DNSSEC

validation in <command>delv</command>.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-b <replaceable class="parameter">address</replaceable></term>

<listitem>

<para>

Sets the source IP address of the query to

<parameter>address</parameter>. 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;"

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-c <replaceable class="parameter">class</replaceable></term>

<listitem>

<para>

Sets the query class for the requested data. Currently,

only class "IN" is supported in <command>delv</command>

and any other value is ignored.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-d <replaceable class="parameter">level</replaceable></term>

<listitem>

<para>

Set the systemwide debug level to <option>level</option>.

The allowed range is from 0 to 99.

The default is 0 (no debugging).

Debugging traces from <command>delv</command> become

more verbose as the debug level increases.

See the <option>+mtrace</option>, <option>+rtrace</option>,

and <option>+vtrace</option> options below for additional

debugging details.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-h</term>

<listitem>

<para>

Display the <command>delv</command> help usage output and exit.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-i</term>

<listitem>

<para>

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 <command>delv</command> to time out. When it

is necessary to examine invalid data to debug a DNSSEC

problem, use <command>dig +cd</command>.)

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-m</term>

<listitem>

<para>

Enables memory usage debugging.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-p <replaceable class="parameter">port#</replaceable></term>

<listitem>

<para>

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.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-q <replaceable class="parameter">name</replaceable></term>

<listitem>

<para>

Sets the query name to <parameter>name</parameter>.

While the query name can be specified without using the

<option>-q</option>, 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).

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-t <replaceable class="parameter">type</replaceable></term>

<listitem>

<para>

Sets the query type to <parameter>type</parameter>, which

can be any valid query type supported in BIND 9 except

for zone transfer types AXFR and IXFR. As with

<option>-q</option>, this is useful to distinguish

query name type or class when they are ambiguous.

it is sometimes necessary to disambiguate names from types.

</para>

<para>

The default query type is "A", unless the <option>-x</option>

option is supplied to indicate a reverse lookup, in which case

it is "PTR".

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-v</term>

<listitem>

<para>

Print the <command>delv</command> version and exit.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-x <replaceable class="parameter">addr</replaceable></term>

<listitem>

<para>

Performs a reverse lookup, mapping an addresses to

a name. <parameter>addr</parameter> is an IPv4 address in

dotted-decimal notation, or a colon-delimited IPv6 address.

When <option>-x</option> is used, there is no need to provide

the <parameter>name</parameter> or <parameter>type</parameter>

arguments. <command>delv</command> automatically performs a

lookup for a name like <literal>11.12.13.10.in-addr.arpa</literal>

and sets the query type to PTR. IPv6 addresses are looked up

using nibble format under the IP6.ARPA domain.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-4</term>

<listitem>

<para>

Forces <command>delv</command> to only use IPv4.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-6</term>

<listitem>

<para>

Forces <command>delv</command> to only use IPv6.

</para>

</listitem>

</varlistentry>

</variablelist>

</refsection>

<refsection><info><title>QUERY OPTIONS</title></info>

<para><command>delv</command>

provides a number of query options which affect the way results are

displayed, and in some cases the way lookups are performed.

</para>

<para>

Each query option is identified by a keyword preceded by a plus sign

(<literal>+</literal>). Some keywords set or reset an

option. These may be preceded by the string

<literal>no</literal> to negate the meaning of that keyword.

Other keywords assign values to options like the timeout interval.

They have the form <option>+keyword=value</option>.

The query options are:

<variablelist>

<varlistentry>

<term><option>+[no]cdflag</option></term>

<listitem>

<para>

Controls whether to set the CD (checking disabled) bit in

queries sent by <command>delv</command>. 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 <command>delv</command> can then

validate internally and report the errors in detail.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>+[no]class</option></term>

<listitem>

<para>

Controls whether to display the CLASS when printing

a record. The default is to display the CLASS.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>+[no]ttl</option></term>

<listitem>

<para>

Controls whether to display the TTL when printing

a record. The default is to display the TTL.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>+[no]rtrace</option></term>

<listitem>

<para>

Toggle resolver fetch logging. This reports the

name and type of each query sent by <command>delv</command>

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.

</para>

<para>

This is equivalent to setting the debug level to 1 in

the "resolver" logging category. Setting the systemwide

debug level to 1 using the <option>-d</option> option will

product the same output (but will affect other logging

categories as well).

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>+[no]mtrace</option></term>

<listitem>

<para>

Toggle message logging. This produces a detailed dump of

the responses received by <command>delv</command> in the

process of carrying out the resolution and validation process.

</para>

<para>

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 <option>-d</option> option will produce the same output

(but will affect other logging categories as well).

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>+[no]vtrace</option></term>

<listitem>

<para>

Toggle validation logging. This shows the internal

process of the validator as it determines whether an

answer is validly signed, unsigned, or invalid.

</para>

<para>

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 <option>-d</option> option will produce the same output

(but will affect other logging categories as well).

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>+[no]short</option></term>

<listitem>

<para>

Provide a terse answer. The default is to print the answer in a

verbose form.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>+[no]comments</option></term>

<listitem>

<para>

Toggle the display of comment lines in the output. The default

is to print comments.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>+[no]rrcomments</option></term>

<listitem>

<para>

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.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>+[no]crypto</option></term>

<listitem>

<para>

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 ]".

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>+[no]trust</option></term>

<listitem>

<para>

Controls whether to display the trust level when printing

a record. The default is to display the trust level.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>+[no]split[=W]</option></term>

<listitem>

<para>

Split long hex- or base64-formatted fields in resource

records into chunks of <parameter>W</parameter> characters

(where <parameter>W</parameter> is rounded up to the nearest

multiple of 4).

<parameter>+nosplit</parameter> or

<parameter>+split=0</parameter> causes fields not to be

split at all. The default is 56 characters, or 44 characters

when multiline mode is active.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>+[no]all</option></term>

<listitem>

<para>

Set or clear the display options

<option>+[no]comments</option>,

<option>+[no]rrcomments</option>, and

<option>+[no]trust</option> as a group.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>+[no]multiline</option></term>

<listitem>

<para>

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 <command>delv</command>

output.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>+[no]dnssec</option></term>

<listitem>

<para>

Indicates whether to display RRSIG records in the

<command>delv</command> output. The default is to

do so. Note that (unlike in <command>dig</command>)

this does <emphasis>not</emphasis> 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

<option>-i</option> or <option>+noroot</option> and

<option>+nodlv</option>.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>+[no]root[=ROOT]</option></term>

<listitem>

<para>

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 <option>-a</option> must be used to specify a file

containing the key.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>+[no]dlv[=DLV]</option></term>

<listitem>

<para>

Indicates whether to perform DNSSEC lookaside validation,

and if so, specifies the name of the DLV trust anchor.

The default is to perform lookaside validation using

a trust anchor of "dlv.isc.org", for which there is a

built-in key. If specifying a different name, then

<option>-a</option> must be used to specify a file

containing the DLV key.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>+[no]tcp</option></term>

<listitem>

<para>

Controls whether to use TCP when sending queries.

The default is to use UDP unless a truncated

response has been received.

</para>

</listitem>

</varlistentry>

</variablelist>

</para>

</refsection>

<refsection><info><title>FILES</title></info>

<para><filename>/etc/bind.keys</filename></para>

<para><filename>/etc/resolv.conf</filename></para>

</refsection>

<refsection><info><title>SEE ALSO</title></info>

<para><citerefentry>

<refentrytitle>dig</refentrytitle><manvolnum>1</manvolnum>

</citerefentry>,

<citerefentry>

<refentrytitle>named</refentrytitle><manvolnum>8</manvolnum>

</citerefentry>,

<citetitle>RFC4034</citetitle>,

<citetitle>RFC4035</citetitle>,

<citetitle>RFC4431</citetitle>,

<citetitle>RFC5074</citetitle>,

<citetitle>RFC5155</citetitle>.

</para>

</refsection>

</refentry>