newbie help needed

[Steve Rudometkin]

Thanks in advance. I have a simple question about DNS setup files.

I need to setup DNS entries for "mycompany.com" which are hosted 
on "dns.othercompany.com". I have seen the following different setups,

and don't know which to use. Let's say there is currently one machine 
running everything for now, with plans for future expansion.

If sombody could give me the +/- of each option, I would appreciate it

very much. I just ordered the DNS/BIND book.
--------------

mycompany.com. IN SOA dns.othercompany.com.
IN A 123.45.67.89

Option 1)	
mail.mycompany.com.	IN A 123.45.67.89
www.mycompany.com.	IN A 123.45.67.89
images.mycompany.com.	IN A 123.45.67.89

Option 2)
mail      IN A 123.45.67.89
www    IN A 123.45.67.89
images IN A 123.45.67.89

Optino 3)
mail.mycompany.com.      IN CNAME mycompany.com.
www.mycompany.com.    IN CNAME mycompany.com. 
images.mycompany.com. IN CNAME mycompany.com.