DNS: List all sub-zones in a zone

I need to use PS to list all the subdomains of a DNS domain. For example:

. domain1
. domain_1.1
. domain_1.2
. domain_1.3
. domain2

Using the Get-DnsServerZone -ComputerName myserver list only "domain1" and "domain2". I need to list all domains and subdomains.

Can anyone help me?

Thank you.