The DNS chapters in Administering Windows Server Hybrid Core Infrastructure describe conditional forwarders as a way to direct queries for specific namespaces to authoritative DNS servers. The text notes:
"A conditional forwarder forwards queries for a designated DNS domain to specified DNS servers," which is used to "integrate split or private namespaces across sites or forests." In this design, Server1 hosts contoso.local and delegates east and west to Server2 and Server3. By configuring Server2 and Server3 with a conditional forwarder for contoso.local pointing to Server1 , any query for contoso.local (including child names like east.contoso.local or west.contoso.local when not answered locally) is sent to Server1.
Server1, being authoritative for the parent, uses the existing delegations to return referrals/answers from the proper child zones. For Internet hosts , all three server s already use root hints , which the course material confirms remains valid alongside conditional forwarding. The documentation also stresses that "authoritative data is answered locally first; forwarding applies only to names the server is not authoritativ e for," so Server2 continues to answer east locally while leveraging Server1 to reach parent and sibling zones . This configuration ensures that all servers can resolve all internal namespaces and Internet hosts .