A Clear-Bit control message is pushed by a node to indicate to its neighbor that it is no longer interested in receiving updates for a particular key from that neighbor.
When a node receives a Clear-Bit message for key K, it clears the interest bit for the neighbor from which the message was sent. If the node's popularity measure for K is low and all of its interest bits are clear, the node also pushes a Clear-Bit message for K. This propagation of Clear-Bit messages toward the authority node for K continues until a node is reached where the popularity of K is high or where at least one interest bit is set.
Clear-Bit messages can be piggybacked onto queries or updates intended for the neighbor, or if there are no pending queries or updates, they can be pushed separately.