Newbie Zone File Question

[tnaves at linkwest.net]

I finally got my first dns server working.  YeeHaa!

I am using BIND 8 and have the following files:

named.conf (with a forwarder defined, a nameserver at my isp)

named.ca (My cache file with only my name server as root server)

my_domain.zone (I have four hosts in this file counting the name server
and localhost)

my_domain_rev.zone (I have three hosts in this file counting the name
server)

local.rev (I have one host in this file, 1.0.0.127.in-addr.arpa.) 

It works fine.

I have a couple of questions with respect to expanding my nameserver.

Currently I am providing name resolution for one subnet only, 192.168.1.0

I have two others: 192.168.2.0 and 192.168.3.0

My question is:

Can I just add hosts on these other subnets to my zone file
(my_domain.zone above) or do I need a zone for each subnet?

How about the in-addr.arpa file for my zone (my_domain.zone above)?

Thanks,

Tom Naves