Editing Dynamic Host Configuration Protocol (section)

===Selecting and configuring IP addresses===
When the server is reusing an IP address from its pool, it may first check (using [[Ping (networking utility)|ping]]) to see if it is not taken already.{{Ref RFC|2131}}{{rp|sec. 2.2}} This may happen if a host is configured manually with an IP address that lies within the DHCP scope.

Before claiming an IP address, the client should probe the newly received address (e.g. with [[Address Resolution Protocol|ARP]]), in order to find if there is another host present in the network with the proposed IP address.{{Ref RFC|2131}}{{rp|sec. 2.2}} If there is no reply, this address does not conflict with that of another host, so it is free to be used. If this probe finds another computer using that address, the client should broadcast a DHCPDECLINE to the DHCP server(s).