The easiest way to find out the different roles and features installed in your 2008 sevrer is to issue a command either in the exchange shell (if it is an exchange server) or command prompt.
ServerManagerCmd -q
All the installed role and features will be highlighted in green colour.
You can output the details onto a text file by adding a switch
ServerManagerCmd -q>C:roles.txt
If you need to find all DNS serves installed at your network (or other networks) you can use this tool and in a second you will have the complete DNS servers list and status (Open/Close)
http://efficient-it-resources.blogspot.com/2010/05/dns-locator.html