beginner questions...for example, recursion on or off? sample zone file.

[Mike]

I have a dns server running with a few domains.  It seems to be
working
well, and I have tested it with dig.

First question, I have seen millions of posting in reference to
recursion.  I am getting the feeling that if a dns server is the
primary master or primary secondary (if that makes sense) then
recursion should be off.  What problems will one see if it is on?

Also, all my zone records are based off an old example I had copies
ages ago and look like this:

$TTL 3D
@       IN      SOA     myzone.com. root.myzone.com. (
                        0530200302      ; serial, todays date + todays
serial #
                        8H              ; refresh, seconds
                        2H              ; retry, seconds
                        4W              ; expire, seconds
                        1D )            ; minimum, seconds
                MX      10 my_other_zone.com.  ; Primary Mail
Exchanger
                TXT     "myzone"
                NS      ns2.myotherzone.com.
                NS      ns3.myotherzone.com.
localhost       A       127.0.0.1
myzone.com.      A       24.123.125.4
www             CNAME   myzone.com.
ftp             CNAME   myzone.com.
myzone.fr303.com. A       24.123.125.4

I have seen recent examples where the IN is put on each line.  As I
said, dig seems to be happy, but is there some other problem I may be
missing?

Thank you in advance.

-Mike