multiple domains on one ip?

[Nate]

Is it possible to have multiple domain names pointintg to one ip?  I have
this set up now, and it SORTA works.  Some people can resolve all the names
fine, but others can't.  I have domain1.com set up as the primary name
server for all of them, and also as the SOA for all of them.  then I have A
records in each zone and CNAMES.  It seems that everyone doesn't have a
problem looking up domain1.com, but they do the other domains I have
pointing there.

here's another weird thing: when querying with different DNS servers, I'll
try domain.com and it won't find it, but then I try http://www.domain.com
and it finds it right away, then after that the server has cached domain.com

Please help, i've been pulling my hair out for a month, have read the whole
o'reilly dns and bind book, and read through a couple RFCs too.  I just
don't get it.

Thanks,
Nate