Provided by: bind9_9.10.3.dfsg.P4-8ubuntu1.19_amd64 
NAME
delv - DNS lookup and validation utility
SYNOPSIS
delv [@server] [-4] [-6] [-a anchor-file] [-b address] [-c class] [-d level] [-i] [-m] [-p port#]
[-q name] [-t type] [-x addr] [name] [type] [class] [queryopt...]
delv [-h]
delv [-v]
delv [queryopt...] [query...]
DESCRIPTION
delv (Domain Entity Lookup & Validation) is a tool for sending DNS queries and validating the results,
using the 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 anchors for the root zone (".") and for
the ISC DNSSEC lookaside validation zone ("dlv.isc.org"). 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
/etc/resolv.conf. 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).
SIMPLE USAGE
A typical invocation of delv looks like:
delv @server name type
where:
server
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 server 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 server argument is provided, delv consults /etc/resolv.conf; if an address is found there, it
queries the name server at that address. If either of the -4 or -6 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).
name
is the domain name to be looked up.
type
indicates what type of query is required — ANY, A, MX, etc. type can be any valid query type. If no
type argument is supplied, delv will perform a lookup for an A record.
OPTIONS
-a anchor-file
Specifies a file from which to read DNSSEC trust anchors. The default is /etc/bind.keys, which is
included with BIND 9 and contains trust anchors for the root zone (".") and for the ISC DNSSEC
lookaside validation zone ("dlv.isc.org").
Keys that do not match the root or DLV trust-anchor names are ignored; these key names can be
overridden using the +dlv=NAME or +root=NAME options.
Note: When reading the trust anchor file, delv treats managed-keys statements and trusted-keys
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 /etc/bind.keys is revoked and rolled over, it will be
necessary to update /etc/bind.keys to use DNSSEC validation in delv.
-b address
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 source port may be specified by appending
"#<port>"
-c class
Sets the query class for the requested data. Currently, only class "IN" is supported in delv and any
other value is ignored.
-d level
Set the systemwide debug level to level. 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
+mtrace, +rtrace, and +vtrace options below for additional debugging details.
-h
Display the delv help usage output and exit.
-i
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.)
-m
Enables memory usage debugging.
-p port#
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.
-q name
Sets the query name to name. While the query name can be specified without using the -q, 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).
-t type
Sets the query type to type, which can be any valid query type supported in BIND 9 except for zone
transfer types AXFR and IXFR. As with -q, 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 -x option is supplied to indicate a reverse lookup, in
which case it is "PTR".
-v
Print the delv version and exit.
-x addr
Performs a reverse lookup, mapping an addresses to a name. addr is an IPv4 address in dotted-decimal
notation, or a colon-delimited IPv6 address. When -x is used, there is no need to provide the name or
type arguments. delv automatically performs a lookup for a name like 11.12.13.10.in-addr.arpa and
sets the query type to PTR. IPv6 addresses are looked up using nibble format under the IP6.ARPA
domain.
-4
Forces delv to only use IPv4.
-6
Forces delv to only use IPv6.
QUERY OPTIONS
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 (+). Some keywords set or reset an
option. These may be preceded by the string no to negate the meaning of that keyword. Other keywords
assign values to options like the timeout interval. They have the form +keyword=value. The query options
are:
+[no]cdflag
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.
+[no]class
Controls whether to display the CLASS when printing a record. The default is to display the CLASS.
+[no]ttl
Controls whether to display the TTL when printing a record. The default is to display the TTL.
+[no]rtrace
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 -d option will product the same output (but will affect other
logging categories as well).
+[no]mtrace
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 the "packets" module of the "resolver"
logging category. Setting the systemwide debug level to 10 using the -d option will produce the same
output (but will affect other logging categories as well).
+[no]vtrace
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 the "validator" module of the "dnssec"
logging category. Setting the systemwide debug level to 3 using the -d option will produce the same
output (but will affect other logging categories as well).
+[no]short
Provide a terse answer. The default is to print the answer in a verbose form.
+[no]comments
Toggle the display of comment lines in the output. The default is to print comments.
+[no]rrcomments
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.
+[no]crypto
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
]".
+[no]trust
Controls whether to display the trust level when printing a record. The default is to display the
trust level.
+[no]split[=W]
Split 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 at
all. The default is 56 characters, or 44 characters when multiline mode is active.
+[no]all
Set or clear the display options +[no]comments, +[no]rrcomments, and +[no]trust as a group.
+[no]multiline
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.
+[no]dnssec
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
-i or +noroot and +nodlv.
+[no]root[=ROOT]
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 -a must be used to
specify a file containing the key.
+[no]dlv[=DLV]
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 -a must be used to specify a
file containing the DLV key.
FILES
/etc/bind.keys
/etc/resolv.conf
SEE ALSO
dig(1), named(8), RFC4034, RFC4035, RFC4431, RFC5074, RFC5155.
COPYRIGHT
Copyright © 2014 Internet Systems Consortium, Inc. ("ISC")