trusted nslookup

[Webmaster]

Running DNS 8.1.2 on Sun Solaris 2.5.1 here. I have two 
questions for the list:

Is there a way to allow only a trusted source nslookup access
(and thereby barring all others) without interfering with
basic services? If yes, how?

Are there any 'holes' in an improperly configured DNS which 
would allow outsiders to remotely generate a complete list
of hosted domains? If yes, how to close the hole?

Thank you in advance!

- Christian