Which statement is true about DHCP operation?
a. When a device that is configured to use DHCP boots, the client broadcasts a DHCPDISCOVER message to identify any available DHCP servers on the network.
b. A client must wait for lease expiration before it sends another DHCPREOUEST message.
c. The DHCPDISCOVER message contains the IP address and sub net masK to be assigned, the IP address of the DNS server, and the IP address of the default gateway.
d. If the client receives several DHCPOFFER messages from different servers, it sends a unicast DHCPREOUEST message to the server from which it chooses to obtain the IP information.
The Correct Answer and Explanation is :
The correct answer is:
a. When a device that is configured to use DHCP boots, the client broadcasts a DHCPDISCOVER message to identify any available DHCP servers on the network.
Explanation:
Dynamic Host Configuration Protocol (DHCP) is used in computer networks to automatically assign IP addresses and other configuration information to devices on a network. It simplifies the management of network settings by automating the process of assigning IP addresses, subnet masks, default gateways, and DNS servers to client devices. Here’s a breakdown of the DHCP operation:
- DHCPDISCOVER Message:
When a device boots up or connects to a network for the first time, it does not have an IP address. The client sends a broadcast message, called a DHCPDISCOVER message, to discover available DHCP servers on the network. This message is broadcast because the client does not yet have an IP address and is unaware of any DHCP server’s location. The server(s) that receive the message will respond with a DHCP offer. - DHCPRENEWAL and DHCPREQUEST:
After receiving a DHCPOFFER message from a DHCP server, the client sends a DHCPREQUEST message to request the offered IP configuration. It is important to note that the DHCPREQUEST message is sent to either confirm an offered lease or to request a renewal of the current lease. Regarding statement b: It is false because a client does not need to wait for lease expiration to send another DHCPREQUEST. It can request an extension or a new lease prior to the expiration if needed. - DHCPOFFER and DHCPREQUEST:
If multiple DHCP servers respond with DHCPOFFER messages, the client will choose one server and send a DHCPREQUEST message back to that server to accept the offered IP configuration. This DHCPREQUEST is sent as a broadcast message if the client is requesting new settings or a unicast message if the client is renewing a lease with the same server. Regarding statement d: The DHCPREQUEST is typically broadcast in this scenario, not unicast. The statement is therefore misleading. - DHCPDISCOVER Message Details:
Statement c is incorrect because the DHCPDISCOVER message does not include the IP address, subnet mask, DNS server, or default gateway. These configurations are typically sent in the DHCPOFFER message by the DHCP server, not the DHCPDISCOVER message.
To summarize, the DHCPDISCOVER message initiates the process by broadcasting to find DHCP servers, which is accurately reflected in option a.