If the interface is connected to a network other than the one on which the configuration was received, one of two things can happen.
However, because the client has received no outside confirmation that this configuration is valid, there is no guarantee that the IP address, router address, and other information are valid. If it has, and if the lease is still valid, the client will use the cached data to configure the interface. When a client and a server cannot communicate with each other, the consequences depend on whether or not the client has a configuration cached from an earlier DHCP transaction. Client Cannot Communicate With the Server Problems can also occur later in the life of a DHCP lease if the client cannot renew its IP addresses. DHCP may fail to configure the client properly, either because DHCP could not communicate with a server, or because, although configuration responses were received, they were incorrect.
When troubleshooting a DHCP client, you must understand certain issues about configuring the client and client-server communication.
