An authentication method based on a time stamp is executed by at least one processor of a server. At least two force renew messages are generated in turn when a configuration of Dynamic Host Configuration Protocol (DHCP) of the server is changed. The at least two force renew messages are encrypted asymmetrically with a private key of the server. The encrypted force renew messages are sent to a client according to a generating order of the force renew messages. A reply message is sent to the client when receiving a renew message from the client.