If this is also a domain controller, trust anchors for this zone will be distributed to all other DNS servers running on ...

If this is also a domain controller, trust anchors for this zone will be distributed to all other DNS servers running on domain controllers in the forest. If this DNS server is not a domain controller, a trust anchor for this zone will be added only to the local trust anchor store. Selecting this option enables DNSSEC validation for this zone on all the servers where trust anchors are distributed.