ltm rule command DNS return

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



DNS::return
       Skips all further processing after TCL execution and sends the DNS
       packet in the opposite direction.

SYNOPSIS
       DNS::return

DESCRIPTION
       This iRules command skips all further processing after TCL execution
       and sends the DNS packet in the opposite direction.  In the DNS_REQUEST
       context, DNS::return signals that no further DNS resolution should
       occur for this request upon completion of the event.  To provide a
       useful response, resource record and header changes must be made in the
       iRule. The next event triggered is the DNS_RESPONSE event.  In the
       DNS_RESPONSE context, DNS::return sends a request back for additional
       processing. This is typically done after the answer, authority and
       additional sections have been cleared and the query changed to obtain a
       different response. Great care must be taken to avoid an infinite loop,
       which can easily occur if the query is not changed before being
       returned to the resolver.  In both contexts, the use of DNS::return
       signals what to do after the event has completed, but does not stop
       processing the current event.

       Note: This command should not be confused with the global command
       return which immediately exits the current event.

       Note: This command functions only in the context of LTM iRules and
       requires the DNS Profile, which is only enabled as part of GTM or the
       DNS Services add-on.

       Syntax

       DNS::return

	    * Skips all further processing after TCL execution and sends the dns
	      packet in the opposite direction.

RETURN VALUE
VALID DURING
       DNS_REQUEST, DNS_RESPONSE

EXAMPLES
	# Send one or more IP addresses for a response to an A query
	# Use on an LTM virtual server with a DNS profile enabled
	when DNS_REQUEST {
		# Log query details
		log local0. "\[DNS::question name\]: [DNS::question name],\
			\[DNS::question class\]: [DNS::question class],
			\[DNS::question type\]: [DNS::question type]"

		# Generate an answer with two A records
		DNS::answer insert "[DNS::question name]. 111 [DNS::question class] [DNS::question type] 1.1.1.1"
		DNS::answer insert "[DNS::question name]. 111 [DNS::question class] [DNS::question type] 1.1.1.2"

		# Stop further processing of the query after this iRule and send the answer to the client
		DNS::return
		return
	}

HINTS
SEE ALSO
CHANGE LOG
       @BIGIP-11.1.0 --First introduced the command.



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