diff --git a/ironic/conf/inspector.py b/ironic/conf/inspector.py
index a7f89c994e..f790ea074a 100644
--- a/ironic/conf/inspector.py
+++ b/ironic/conf/inspector.py
@@ -34,11 +34,14 @@ opts = [
                help=_('endpoint to use as a callback for posting back '
                       'introspection data when boot is managed by ironic. '
                       'Standard keystoneauth options are used by default.')),
-    cfg.BoolOpt('require_managed_boot', default=False,
+    cfg.BoolOpt('require_managed_boot', default=None,
                 help=_('require that the in-band inspection boot is fully '
-                       'managed by ironic. Set this to True if your '
-                       'installation of ironic-inspector does not have a '
-                       'separate PXE boot environment.')),
+                       'managed by the node\'s boot interface. Set this to '
+                       'True if your installation does not have a separate '
+                       '(i)PXE boot environment for node discovery. Set '
+                       'to False if you need to inspect nodes that are not '
+                       'supported by boot interfaces (e.g. because they '
+                       'don\'t have ports).')),
 ]
 
 
diff --git a/ironic/drivers/modules/inspector/interface.py b/ironic/drivers/modules/inspector/interface.py
index e720770036..75d51f9711 100644
--- a/ironic/drivers/modules/inspector/interface.py
+++ b/ironic/drivers/modules/inspector/interface.py
@@ -164,6 +164,14 @@ def _start_managed_inspection(task):
 class Inspector(base.InspectInterface):
     """In-band inspection via ironic-inspector project."""
 
+    def __init__(self):
+        super().__init__()
+        if CONF.inspector.require_managed_boot is None:
+            LOG.warning("The option [inspector]require_managed_boot will "
+                        "change its default value to True in the future. "
+                        "Set it to an explicit boolean value to avoid a "
+                        "potential breakage.")
+
     def get_properties(self):
         """Return the properties of the interface.
 
diff --git a/releasenotes/notes/require-managed-boot-7d8965d4ac5fbd21.yaml b/releasenotes/notes/require-managed-boot-7d8965d4ac5fbd21.yaml
new file mode 100644
index 0000000000..106664b8ea
--- /dev/null
+++ b/releasenotes/notes/require-managed-boot-7d8965d4ac5fbd21.yaml
@@ -0,0 +1,8 @@
+---
+deprecations:
+  - |
+    The default value of the ``[inspector]require_managed_boot`` option will
+    change from ``False`` to ``True`` in the future, causing in-band inspection
+    to fail if the boot interface cannot prepare the ramdisk boot (e.g. in case
+    of missing ports). Please set this option to an explicit value to avoid
+    the behavior change.