On machines with a coarse monotonic clock (here: TP-Link RE200 powered
by a MediaTek MT7620A) it can happen that the two DNS requests (for A
and AAAA) share the same transaction ID. If this happens the second
reply is wrongly dropped and nslookup reports "No answer".
Fix this by ensuring that the transaction IDs are unique.
Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>