DHCP exhaustion is a situation where the DHCP server runs out of available IP addresses to assign to clients. This can happen due to misconfiguration, malicious attacks, or high demand. When a client requests an IP address from the DHCP server and does not receive a response, it may resort to using an APIPA address, which is a self-assigned address in the range of 169.254.0.1 to 169.254.255.254. APIPA addresses are only valid for local communication and cannot access the internet or other networks. Therefore, a workstation showing an APIPA address indicates that it failed to obtain a valid IP address from the DHCP server, most likely due to DHCP exhaustion