ltm rule command DNS header

iRule(1)		      BIG-IP TMSH Manual		      iRule(1)



DNS::header
       Gets (v11.0+) or sets (v11.1+) simple bits or byte fields.

SYNOPSIS
       DNS::header (('id' (UNSIGNED_SHORT)?)
			    | ('qr' (BOOLEAN)?)
			    | ('opcode' ('query' | 'QUERY' | 'iquery' |
       'IQUERY'
					 | 'status' | 'STATUS' | 'notify' |
       'NOTIFY'
					 | 'update' | 'UPDATE')?)
			    | ('aa' (BOOLEAN)?)
			    | ('tc' (BOOLEAN)?)
			    | ('rd' (BOOLEAN)?)
			    | ('ra' (BOOLEAN)?)
			    | ('ad' (BOOLEAN)?)
			    | ('cd' (BOOLEAN)?)
			    | ('rcode' ('noerror' | 'NOERROR' | 'formerr' |
       'FORMERR'
					| 'servfail' | 'SERVFAIL' | 'nxdomain'
       | 'NXDOMAIN'
					| 'notimpl' | 'NOTIMPL' | 'refused' |
       'REFUSED' | 'yxdomain'
					| 'YXDOMAIN' | 'yxrrset' | 'YXRRSET' |
       'nxrrset' | 'NXRRSET'
					| 'notauth' | 'NOTAUTH' | 'notzone' |
       'NOTZONE')?)
			    | ('qdcount' (UNSIGNED_SHORT)?)
			    | ('ancount' (UNSIGNED_SHORT)?)
			    | ('nscount' (UNSIGNED_SHORT)?)
			    | ('arcount' (UNSIGNED_SHORT)?))

DESCRIPTION
       This iRules command gets or sets simple bits or byte fields. Read-only
       form introduced in v11.0, Read-write capability added in v11.1.

       Note: This command requires the DNS Profile, which is only enabled as
       part of GTM or the DNS Services add-on.

       Syntax

       DNS::header
       
       [value]

	    * Gets or sets simple bits or byte fields. Return value is always an
	      integer except for successful recognition of the rcode or opcode
	      fields, where a string is returned
		 + rcode
		      o NOERROR
		      o FORMERR
		      o SERVFAIL
		      o NXDOMAIN
		      o NOTIMPL
		      o REFUSED
		      o YXDOMAIN
		      o YXRRSET
		      o NXRRSET
		      o NOTAUTH
		      o NOTZONE
		 + opcode
		      o QUERY
		      o IQUERY
		      o STATUS
		      o NOTIFY
		      o UPDATE

RETURN VALUE
VALID DURING
       DNS_REQUEST, DNS_RESPONSE, GLOBAL_GTM

EXAMPLES
	# Refuse all queries from a specific ip
	when DNS_REQUEST {
	    if { [IP::client_addr] equals "192.168.1.245" } {
		DNS::answer clear
		DNS::header rcode REFUSED
		DNS::return
		return
	    }
	}

HINTS
SEE ALSO
CHANGE LOG
       @BIGIP-11.0.0 --First introduced the command.



BIG-IP				  2017-01-31			      iRule(1)