Using the circular overlay in Figure 1(a), now suppose that peer 3 wants to determine which peer in the DHT is responsible for key 11 [either for inserting or querying for a (key-value) pair]. Using the circular overlay, the origin peer (peer 3) creates a message saying "Who is responsible for key 11?" and sends this message to its successor, peer 4. Whenever a peer receives such a message, because it knows the identifier of its successor, it can determine whether it is responsible (that is, Closest to) the key in question. If a peer is not responsible for the key, it simply sends the message to its successor. So, for instance, when peer 4 receives the message asking about key 11, it determines that it is not responsible for the key (because its successor is closer to the key), so it just passes the message to its own successor, namely, peer 5. This process continues until the message arrives at peer 12, who determines that it is the closest peer to key 11. At this point, peer 12 can send a message back to the origin, peer 3, indicating that it is responsible for key 11.