+dit(bf(reverse lookup)) Controls whether the daemon performs a reverse lookup
+on the client's IP address to determine its hostname, which is used for
+"hosts allow"/"hosts deny" checks and the "%h" log escape. This is enabled by
+default, but you may wish to disable it to save time if you know the lookup will
+not return a useful result, in which case the daemon will use the name
+"UNDETERMINED" instead.
+
+If this parameter is enabled globally (even by default), rsync performs the
+lookup as soon as a client connects, so disabling it for a module will not
+avoid the lookup. Thus, you probably want to disable it globally and then
+enable it for modules that need the information.
+