4. End of transaction: DHCP ACK

Here the server acknowledges the client's request for an IP address. The basics of the packet are the same as for a DHCP OFFER. Once a client receives this packet, it keeps the IP address given until the expiry of the DHCP lease or until it sends a subsequent DHCP request.

   UDP 163.1.15.254:67 (00:D0:BC:00:11:22) > 
       163.1.15.99:68 (00:00:39:1C:0C:32) DHCP ACK

A variation at this stage is for the server to send a DHCP NAK (not acknowledged) which denies the client the IP address it requested.

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