Standard practice with DNS is to lookup either A or AAAA records
	and use the results if it succeeds. Only looking up the other if
	the first attempt fails or otherwise produces no results.

	That policy however will cause squid to produce error pages for some
	servers that advertise AAAA but are unreachable over IPv6.

	If this is ON  squid will always lookup both AAAA and A, using both.
	If this is OFF squid will lookup AAAA and only try A if none found.

	WARNING: There are some possibly unwanted side-effects with this on:
		*) Doubles the load placed by squid on the DNS network.
		*) May negatively impact connection delay times.