This is a Windows system installed file with Windows File Protection (WFP) enabled.
There are 45 versions of dsuiext.dll in the wild, the latest version being 6.3.9600.16384 (winblue_rtm.130821-1623). The average file size is about 314.54 KB.
A directory service is a customizable information store that functions as a single point from which users can locate resources and services distributed throughout the network. This customizable information store also gives administrators a single point for managing its objects and their attributes. Although this information store appears as a single point to the users of the network, it is actually most often stored in a distributed form.
(Note, the behaviors below are for all versions of dsuiext.dll, select a unique version for details.)
Located in the registry at 'SOFTWARE\Microsoft\Windows\CurrentVersion\Shell Extensions\Approved'
United States installs about 48.15% of Directory Service Common UI.