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Net::DNS::Header(3)   User Contributed Perl Documentation  Net::DNS::Header(3)
NAME
       Net::DNS::Header - DNS packet header
SYNOPSIS
           use Net::DNS;
           $packet = new Net::DNS::Packet;
           $header = $packet->header;
DESCRIPTION
       "Net::DNS::Header" represents the header portion of a DNS packet.
METHODS
   $packet->header
           $packet = new Net::DNS::Packet;
           $header = $packet->header;
       Net::DNS::Header objects emanate from the Net::DNS::Packet header()
       method, and contain an opaque reference to the parent Packet object.
       Header objects may be assigned to suitably scoped lexical variables.
       They should never be stored in global variables or persistent data
       structures.
   string
           print $packet->header->string;
       Returns a string representation of the packet header.
   print
           $packet->header->print;
       Prints the string representation of the packet header.
   id
           print "query id = ", $packet->header->id, "\n";
           $packet->header->id(1234);
       Gets or sets the query identification number.
       A random value is assigned if the argument value is undefined.
   opcode
           print "query opcode = ", $packet->header->opcode, "\n";
           $packet->header->opcode("UPDATE");
       Gets or sets the query opcode (the purpose of the query).
   rcode
           print "query response code = ", $packet->header->rcode, "\n";
           $packet->header->rcode("SERVFAIL");
       Gets or sets the query response code (the status of the query).
   qr
           print "query response flag = ", $packet->header->qr, "\n";
           $packet->header->qr(0);
       Gets or sets the query response flag.
   aa
           print "answer is ", $packet->header->aa ? "" : "non-", "authoritative\n";
           $packet->header->aa(0);
       Gets or sets the authoritative answer flag.
   tc
           print "packet is ", $packet->header->tc ? "" : "not ", "truncated\n";
           $packet->header->tc(0);
       Gets or sets the truncated packet flag.
   rd
           print "recursion was ", $packet->header->rd ? "" : "not ", "desired\n";
           $packet->header->rd(0);
       Gets or sets the recursion desired flag.
   ra
           print "recursion is ", $packet->header->ra ? "" : "not ", "available\n";
           $packet->header->ra(0);
       Gets or sets the recursion available flag.
   z
       Unassigned bit, should always be zero.
   ad
           print "The result has ", $packet->header->ad ? "" : "not", "been verified\n";
       Relevant in DNSSEC context.
       (The AD bit is only set on answers where signatures have been
       cryptographically verified or the server is authoritative for the data
       and is allowed to set the bit by policy.)
   cd
           print "checking was ", $packet->header->cd ? "not" : "", "desired\n";
           $packet->header->cd(0);
       Gets or sets the checking disabled flag.
   qdcount, zocount
           print "# of question records: ", $packet->header->qdcount, "\n";
       Returns the number of records in the question section of the packet.
       In dynamic update packets, this field is known as "zocount" and refers
       to the number of RRs in the zone section.
   ancount, prcount
           print "# of answer records: ", $packet->header->ancount, "\n";
       Returns the number of records in the answer section of the packet which
       may, in the case of corrupt packets, differ from the actual number of
       records.  In dynamic update packets, this field is known as "prcount"
       and refers to the number of RRs in the prerequisite section.
   nscount, upcount
           print "# of authority records: ", $packet->header->nscount, "\n";
       Returns the number of records in the authority section of the packet
       which may, in the case of corrupt packets, differ from the actual
       number of records.  In dynamic update packets, this field is known as
       "upcount" and refers to the number of RRs in the update section.
   arcount, adcount
           print "# of additional records: ", $packet->header->arcount, "\n";
       Returns the number of records in the additional section of the packet
       which may, in the case of corrupt packets, differ from the actual
       number of records.  In dynamic update packets, this field is known as
       "adcount".
EDNS Protocol Extensions
   do
           print "DNSSEC_OK flag was ", $packet->header->do ? "not" : "", "set\n";
           $packet->header->do(1);
       Gets or sets the EDNS DNSSEC OK flag.
   Extended rcode
       EDNS extended rcodes are handled transparently by
       $packet->header->rcode().
   UDP packet size
           $udp_max = $packet->header->size;
           $udp_max = $packet->edns->size;
       EDNS offers a mechanism to advertise the maximum UDP packet size which
       can be assembled by the local network stack.
       UDP size advertisement can be viewed as either a header extension or an
       EDNS feature.  Endless debate is avoided by supporting both views.
   edns
           $header  = $packet->header;
           $version = $header->edns->version;
           @options = $header->edns->options;
           $option  = $header->edns->option(n);
           $udp_max = $packet->edns->size;
       Auxiliary function which provides access to the EDNS protocol extension
       OPT RR.
COPYRIGHT
       Copyright (c)1997 Michael Fuhr.
       Portions Copyright (c)2002,2003 Chris Reinhardt.
       Portions Copyright (c)2012 Dick Franks.
       All rights reserved.
LICENSE
       Permission to use, copy, modify, and distribute this software and its
       documentation for any purpose and without fee is hereby granted,
       provided that the above copyright notice appear in all copies and that
       both that copyright notice and this permission notice appear in
       supporting documentation, and that the name of the author not be used
       in advertising or publicity pertaining to distribution of the software
       without specific prior written permission.
       THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
       OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
       MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
       IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
       CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
       TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
SEE ALSO
       perl, Net::DNS, Net::DNS::Packet, Net::DNS::RR::OPT RFC 1035 Section
       4.1.1
perl v5.26.3                      2018-02-09               Net::DNS::Header(3)