ddns hosts and flapping status...

hello all,

i'm trying to monitor some ddns hosts, but i get some strange results..
in hosts.cfg i have

subpage Metron6-Gateways Metron 6 Gateways
title Metron 6 Gateways
0.0.0.0 metron6-vdsl1.ddns.net
0.0.0.0 metron6-vdsl2.ddns.net
0.0.0.0 metron6-adsl1.ddns.net

and the results are:
WARNING: Flapping status
Tue Sep 12 02:26:15 2017 conn NOT ok : DNS lookup failed
Unable to resolve hostname metron6-adsl1.ddns.net
System unreachable for 287 poll periods (83744 seconds)
0.0.0.0 is alive (23.0 ms)regards,

the hostname is certainly resolvable...
the graph attached is more strange...


Metron 6 (six)

user-17e4b93d552a@xymon.invalid