When communicating between the client and the server by the DHCP client in the options box specifies the last issued to the client IP address. That is, the client computer remembers your last received address and reports it to the dhcp server. The DHCP server can score on this field and give any address of the range, but in most cases it will check and try to give the old address.
Read more about the work of the Protocol DHCP: https://ru.wikipedia.org/wiki/DHCP
The answer to your question starts with "Consider the example of the process of obtaining the IP address by the client from the DHCP server."