delv

DELV(1)                              BIND9                             DELV(1)

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 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 and DS 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 /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 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 +root=NAME options.

           Note: When reading the trust anchor file, delv treats
           trust-anchorsinitial-key and static-key entries identically. That
           is, even if a key is configured with initial-key, indicating that
           it is meant to be used only as an initializing key for RFC 5011 key
           maintenance, it is still treated by delv as if it had been
           configured as a static-key.  delv does 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
           "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
           "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.

       +[no]root[=ROOT]
           Indicates whether to perform conventional 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]tcp
           Controls whether to use TCP when sending queries. The default is to
           use UDP unless a truncated response has been received.

       +[no]unknownformat
           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.

       +[no]yaml
           Print response data in YAML format.

FILES
       /etc/bind.keys

       /etc/resolv.conf

SEE ALSO
       dig(1), named(8), RFC4034, RFC4035, RFC4431, RFC5074, RFC5155.

AUTHOR
       Internet Systems Consortium, Inc.

COPYRIGHT
       Copyright (C) 2014-2020 Internet Systems Consortium, Inc. ("ISC")

ISC                               2014-04-23                           DELV(1)