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						      2020-06-23					     iRule(1)