Resolve Azure and on-premises domains
Azure DNS Private Resolver
The Azure DNS Private Resolver is a service that can resolve on-premises DNS queries for Azure DNS private zones. Previously, it was necessary to deploy a VM-based custom DNS resolver, or use non-Microsoft DNS, DHCP, and IPAM (DDI) solutions to perform this function.
Configure on-premises DNS conditional forwarders
The procedure to configure on-premises DNS depends on the type of DNS server you're using. In the following example, a Windows DNS server at 10.100.0.2 is configured with a conditional forwarder for the private DNS zone azure.contoso.com. The conditional forwarder is set to forward queries to 10.10.0.4, which is the inbound endpoint IP address for your Azure DNS Private Resolver. There's another IP address also configured here to enable DNS failover.

Reference:
https://learn.microsoft.com/en-us/azure/dns/private-resolver-hybrid-dns