This interface supports integration with BIND using RNDC keys.
No explicit handler is required to consume this interface in charms that consume this interface.
This state is set when a relation of type bind-rndc is detected, but the data may not have yet been presented by the providing charm.
This state is set when the providing application unit has set all required data items on the interface.
algorithm - RNDC algorithm to use.
rndckey - key to use to secure RNDC commands.
private_address - address of providing application unit.
In this case, sync_all_zones is a function provided by the consuming charm.