If set to ``yes``, DNSSEC validation is enabled, but a trust anchor must be
manually configured using a :any:`trust-anchors` statement (or the
:any:`managed-keys` or :any:`trusted-keys` statements, both deprecated). If
- there is no configured trust anchor, validation does not take place.
+ :any:`trust-anchors` is not configured, it is a configuration error. If
+ :any:`trust-anchors` does not include a valid root key, then validation does
+ not take place for names which are not covered by any of the configured trust
+ anchors.
If set to ``no``, DNSSEC validation is disabled. (Note: the resolver
will still set the DO bit in outgoing queries indicating that it can
trust anchors, discussed in :ref:`trust_anchors_description`)
up-to-date without intervention from the DNS administrator.
+When using *yes*, please note that if :any:`trust-anchors` does not include a
+valid root key, then validation does not take place for names which are not
+covered by any of the configured trust anchors.
+
We recommend using the default *auto* unless there is a good reason to
require a manual trust anchor. To learn more about trust anchors,
please refer to :ref:`trusted_keys_and_managed_keys`.