what it is directory
What is a directory? Common-sense examples: printed (offline) directories: phone book, TV Guide Online directories are dynamic, flexible, can be secure, can be personalized Some different kinds of directories: NOS-based: Novell NDS, MS Active Directory Application-specific: Lotus Notes, MS Exchange Purpose-specific: narrow scope, not extensible, e. ... databases: directories have a higher read-to-write ratio directories are more easily extended directories are more widely distributed directories are replicated on a higher scale directories have very different performance characteristics support for standards is more important in directories Summary: "A directory is a specialized database that is read or searched far more often than it is written to.