You have to decide which accounts you want to read. Using the filter
(cn=*), you are telling AD to give you every object where the
cn attribute has a value. That will match to almost every AD object in your domain, including computers, which I don't think you want.
If you want to find all users on the domain, you can use this:
If you want to find one specific user, the query will depend on what identifier you have for that user. For example, if you know their username (let's say "PeimanF"), then the query would look like this: