Unity NAS Server failover / DNS issue

We have currently deployed our Unity650F arrays and we are performing NAS failover testing between our Primary and DR sites. Each site has a different VLAN / IP range for our NAS environment and as such we have clicked on the option on the DR NAS “Override address” to specify a different IP once in DR.

The NAS failover works as expected however it appears that the Unity system is not performing a DNS remove before adding the DR DNS entry.

We have performed the same NAS failover test on our VNX arrays and performed a capture of the DNS packets and we can clearly see that under the VNX array the original source datamover performs a DNS removal and the datamover receiving the NAS performs a DNS add.

We have had to manually adjust the NAS server settings using the svc_nas commands directly on the array so that the NAS automatically creates a PTR record:

svc_nas SLO-NAS-F02P-P -param -facility dns -modify updatePTRrecord -value 1

However again on failover its simply adding an additional PTR record. Is there something else you need to configure either through the GUI or cli which gives the Unity array the option to perform a DNS delete then add when performing a NAS failover?