The following key points are important for a better understanding of Azure reverse DNS zone:

• It's commonly known that to create a classless reverse DNS zone in a DNS server, you need to put a forward slash in the zone name. However, when you create the reverse zone in Azure, you will have to replace the forward slash with a hyphen, because Azure does not support zones with forward slashes in their names.
• Like IPv4 record set names for PTR records, IPv6 record set names must be written in reverse order.
• Zero compression is not supported for IPv6 while writing the record set name for a PTR record.