If the client receives a DHCPNAK message, the client restarts the configuration process. The client times out and retransmits the DHCPREQUEST message if the client receives neither a DHCPACK or a DHCPNAK message. The client retransmits the DHCPREQUEST according to the retransmission algorithm in section 4.1. The client should choose to retransmit the DHCPREQUEST enough times to give adequate probability of contacting the server without causing the client (and the user of that client) to wait overly long before giving up; e.g., a client retransmitting as described in section 4.1 might retransmit the DHCPREQUEST message four times, for a total delay of 60 seconds, before restarting the initialization procedure. If the client receives neither a DHCPACK or a DHCPNAK message after employing the retransmission algorithm, the client reverts to INIT state and restarts the initialization process. The client SHOULD notify the user that the initialization process has failed and is restarting. 6. The client may choose to relinquish its lease on a network address by sending a DHCPRELEASE message to the server. The client identifies the lease to be released with its 'client identifier', or 'chaddr' and network address in the DHCPRELEASE message. If the client used a 'client identifier' when it obtained the lease, it MUST use the same 'client identifier' in the DHCPRELEASE message. 3.2 Client-server interaction - reusing a previously allocated network address If a client remembers and wishes to reuse a previously allocated network address, a client may choose to omit some of the steps described in the previous section. The timeline diagram in figure 4 shows the timing relationships in a typical client-server interaction for a client reusing a previously allocated network address.