DHCP automatically assigns IP configuration to clients. DORA process: Discover (broadcast) → Offer → Request → Acknowledge. Server: UDP 67. Client: UDP 68.
DHCP starvation floods the server with fake MAC addresses exhausting the IP pool. Rogue DHCP server attack assigns attacker's IP as the default gateway (MITM). DHCP snooping on switches prevents both attacks by only allowing DHCP from trusted ports.