While the FLDB can only contain up to four addresses for a given File Server or FL Server, such servers can have more than four connections to the network. In such instances, the DCE RPC mechanism can allow the IP layer to choose a source address for a server response that is different, and presumably more efficient, than the specified destination of the corresponding request. In this case, the chosen server address is likely to be a function of the client address to which the response is being set; however, the exact algorithm for choosing the address will differ for each operating system vendor. Such a routing decision is observed by the Cache Manager as a change in the server-binding's address.
Should the IP layer select a different server address, then this connection becomes the connection used by the Cache Manager, regardless of its preference rank or whether or not it is one of the addresses listed in the FLDB for a given server. This scenario is shown in the following figure.
An Example of the IP Layer Overriding the Cache Manager's Preference
Should the IP layer select a different connection and override the preference choice, the cm getpreferences command returns the address of the currently used connections (the connection selected by the IP layer) as the entry in the preference list, even though it may not be listed in the FLDB.