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delv(1)                             BIND 9                             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 forward-
       ing.

       By default, responses are validated using built-in DNSSEC trust  anchor
       for the root zone ("."). Records returned by delv are either fully val-
       idated 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 MDASH ANY, A, MX, etc.
              type can be any valid query type. If no type  argument  is  sup-
              plied, 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 alter-
              nate key name can be specified using the +root=NAME options.

              Note:  When  reading  the  trust   anchor   file,   delv   treat
              trust-anchors  initial-key  and static-key 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 val-
              idation 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  speci-
              fied  without  using the -q, it is sometimes necessary to disam-
              biguate 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-delim-
              ited  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 +key-
       word=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 reso-
              lution and validation process: this includes including the orig-
              inal  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 "val-
              idator" 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 near-
              est 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), RFC 4034, RFC 4035, RFC 4431, RFC 5074, RFC 5155.


AUTHOR

       Internet Systems Consortium


COPYRIGHT

       2020, Internet Systems Consortium



9.16.4                            2020-06-10                           delv(1)

bind 9.16.4 - Generated Thu Jun 18 15:29:16 CDT 2020
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