Try like:
TextBetween( DN, 'CN=', ',') as [Site Name]
Case sensitive search in qlik has some issues (bug). I have tried an alternate method. Few of the string functions in qlik are case sensitive, we can probably use it with a little trick and find a way of case sensitive search. May be some easier solution would be there too, some experts can suggest. The way I tried is like:
Count( {<DN={"=SubStringCount(Replace(DN, 'ADM_', 'xxx'),'xxx')"}>} DN)
Note: Assuming there would be no 'xxx' in your DN field, otherwise you can use anything that is not possible (may be like '%%%%') in the DN as sub string.
Update: Substringcount() itself is case sensitive, so we can remove the replace() and make it bit simpler, like:
Count( {<DN={"=SubStringCount(DN, 'ADM_')"}>} DN)
