DHCP is a network protocol used to automate the process of assigning IP addresses and other communication parameters (like available servers, for example, dns servers, file servers, etc.).

DORA process:

1. Discover (client looks for dhcp servers using broadcast)
2. Offer (dhcp server responds with an available IP address)
3. Request (client accepts the offer)
4. Acknowledge (the server confirms the assignment)

Server can check with ping if the ip address it's trying to reuse is already taken. Clients check with ARP if the given ip address isn't already taken by another host in the network.