Sequence of events
1) The DHCP server (Option 81 is configured) registers the IPv4 records for the client machine
2) When 6to4 is enabled, then the DNS client registers the AAAA record on the DNS server, however; before the DNS client registers the AAAA record, stale records need to be considered, so the DNS Client sends IPv6 as well as well as a IPv4 record with a Time To Live (TTL) equal to 0.
When the IPv4 A record is registered with a TTL = 0, the TTL = 0 indicates to delete the A record.
1- Disable DHCP server to send IPv4 record if client is registering.
2- Disable 6to4 on the client and keep using DHCP option 81.