Remove IPv6 Address from Forward Lookup Zone


I have disabled IPv6 in the network settings on a 5.0.1:


Nevertheless, I find an IPv6 entry in the forward lookup zone:


This means that a ping srv01 returns an IPv6 address:

root@lt001:/home/s.gehr# ping srv01
PING srv01(fd2d:caef:b987:4a90:1418:6aff:fe6f:b673 (fd2d:caef:b987:4a90:1418:6aff:fe6f:b673)) 56 Datenbytes
64 Bytes von fd2d:caef:b987:4a90:1418:6aff:fe6f:b673 (fd2d:caef:b987:4a90:1418:6aff:fe6f:b673): icmp_seq=1 ttl=64 Zeit=11.9 ms
64 Bytes von fd2d:caef:b987:4a90:1418:6aff:fe6f:b673 (fd2d:caef:b987:4a90:1418:6aff:fe6f:b673): icmp_seq=2 ttl=64 Zeit=1.26 ms

If I remove the IPv6 address from the forward lookup zone, the ping returns the IPv4 address. After the master has been restarted, the entry is available again.

Where does this come from although IPv6 is deactivated and how can I get rid of it?

with best