A DHCP client on an Ethernet segment with a DHCP server at 192.168.1.1 will obtain an IP by sending which message?

A DHCP client on an Ethernet segment with a DHCP server at 192.168.1.1 will obtain an IP by sending which message?

• A. DHCPDISCOVER to FF-FF-FF-FF-FF-FF
• B. DHCPREQUEST
• C. DHCPACK
• D. DHCPOFFER

Answer: (A)

DHCP uses a discovery phase when a device has no IP address. Because the client doesn’t yet know an IP or a server, it broadcasts a DHCPDISCOVER message to find a DHCP server on the local network. This message is sent to the Ethernet broadcast address (FF:FF:FF:FF:FF:FF) and, at the IP level, to the broadcast address 255.255.255.255, so any DHCP server on the segment can see it. The server at 192.168.1.1 will respond with a DHCPOFFER offering an IP, and then the client proceeds with a DHCPREQUEST to accept the offer, followed by a DHCPACK from the server to finalize the assignment. So the starting message the client sends to obtain an IP is the DHCPDISCOVER to the broadcast address.

DHCP uses a discovery phase when a device has no IP address. Because the client doesn’t yet know an IP or a server, it broadcasts a DHCPDISCOVER message to find a DHCP server on the local network. This message is sent to the Ethernet broadcast address (FF:FF:FF:FF:FF:FF) and, at the IP level, to the broadcast address 255.255.255.255, so any DHCP server on the segment can see it. The server at 192.168.1.1 will respond with a DHCPOFFER offering an IP, and then the client proceeds with a DHCPREQUEST to accept the offer, followed by a DHCPACK from the server to finalize the assignment. So the starting message the client sends to obtain an IP is the DHCPDISCOVER to the broadcast address.