Which statement is correct regarding the operation of DHCP?

D

DHCP stands for Dynamic Host Configuration Protocol. It is a protocol used by hosts (such as computers, printers, etc.) to obtain IP addresses and other network configuration information automatically from a DHCP server. In the context of the given question, we will discuss the operation of DHCP in detecting and resolving address conflicts.

An address conflict occurs when two or more hosts are assigned the same IP address. This can happen due to various reasons, such as a misconfigured DHCP server, a rogue DHCP server, or manual IP address assignment that overlaps with the DHCP pool. Address conflicts can cause network connectivity issues and must be resolved promptly.

Let's go through each of the options and see which statement is correct regarding the operation of DHCP:

A. A DHCP client uses a ping to detect address conflicts. This statement is not correct. DHCP clients do not use a ping to detect address conflicts. Instead, they rely on a process called Address Resolution Protocol (ARP) to detect conflicts. When a DHCP client receives an IP address from a DHCP server, it sends an ARP request to check if the IP address is already in use. If it receives a response, it knows that there is an address conflict.

B. A DHCP server uses a gratuitous ARP to detect DHCP clients. This statement is not correct either. Gratuitous ARP is a type of ARP message in which a host sends an ARP request for its own IP address. It is used for various purposes, such as updating ARP caches or detecting IP address conflicts. However, DHCP servers do not use gratuitous ARP to detect DHCP clients. Instead, they rely on DHCP Discover messages sent by clients to detect them.

C. A DHCP client uses a gratuitous ARP to detect a DHCP server. This statement is also not correct. A gratuitous ARP message is not used by DHCP clients to detect DHCP servers. Instead, when a client needs an IP address, it sends a DHCP Discover message broadcast on the local network. The DHCP server(s) on the network respond with a DHCP Offer message, and the client selects one of them based on various criteria.

D. If an address conflict is detected, the address is removed from the pool and an administrator must resolve the conflict. This statement is partially correct. When a DHCP server detects an address conflict, it marks the IP address as "bad" or "used" in its database. The IP address is then removed from the pool, which means that the DHCP server will not assign it to any other client. However, the resolution of the conflict depends on the DHCP server's configuration. Some DHCP servers may notify the administrator or log the conflict, while others may not. It is up to the administrator to resolve the conflict, either by reconfiguring the DHCP server or manually assigning a new IP address to one of the conflicting hosts.

E. If an address conflict is detected, the address is removed from the pool for an amount of time configurable by the administrator. This statement is not correct. DHCP servers do not typically remove the conflicting IP address from the pool for a configurable amount of time. Instead, the address is marked as "bad" or "used" and is not assigned to any other client until the administrator resolves the conflict.

F. If an address conflict is detected, the address is removed from the pool and will not be reused until the server is rebooted. This statement is not correct either. DHCP servers do not typically reuse bad or used IP addresses even after a reboot. The IP address remains marked as "bad" or "used" in the DHCP server's database until the administrator resolves the conflict or manually removes the entry from the database.

In summary, option D is the correct statement regarding the operation of DHCP in detecting and resolving address conflicts.