An opportunistic directory cache and method of usage reduce the number of calls between a client and server for file information, reducing the wastage of network resources and server resources. The expirable directory cache can be refreshed any time an appropriate directory enumeration call is made to the server, and is capable of being partially rather than completely invalidated in response to an indication that the file information of a file listed in the cache has or will change. If the affected file is identifiable, the entry in the cache for that file is invalidated, i.e. it is no longer useful for serving file information. If the affected file is not identifiable, then a first character projection of the file name is invalidated in the cache. In this manner, the directory cache is maintained with minimum resources and is persisted to the greatest extent possible, increasing its likelihood of usefulness.