- Comma separated list of netmasks
- Default: 0.0.0.0/0, ::, !127.0.0.0/8, !10.0.0.0/8, !100.64.0.0/10, !169.254.0.0/16, !192.168.0.0/16, !172.16.0.0/12, !::1/128, !fc00::/7, !fe80::/10
-List of requestor netmasks for which the requestor IP Address should be used as the :rfc:`EDNS Client Subnet <7871>` for outgoing queries. Instead, `ecs-scope-zero-address`_ would be used.
+List of requestor netmasks for which the requestor IP Address should be used as the :rfc:`EDNS Client Subnet <7871>` for outgoing queries. Outgoing queries for requestors that do not match this list will use the `ecs-scope-zero-address`_ instead.
Valid incoming ECS values from `use-incoming-edns-subnet`_ are not replaced.
+Regardless of the value of this setting, ECS values are only sent for outgoing queries matching the conditions in the `edns-subnet-whitelist`_ setting. This setting only controls the actual value being sent.
+
This defaults to not using the requestor address inside RFC1918 and similar "private" IP address spaces.
.. _setting-ecs-ipv4-bits: