newbie: format for sub-C-class

[birgitt]

I have a a.b.c.64/27 sub-C class of IPs and write my zone files. I am not quite sure if my 
format is correct.

My primary name server will be at a.b.c.67 under domain me1.my-1-domain.com. I have a router
at a.b.c.65. a.b.c. 66 is used for something else, and my secondary name server will be a.b.c.68
on another Linux box under.me2.my-2-domain.com.

On my  me1.my-1-domain.com I want to virtually host my-3-domain.com to my-20-domain.com.
and run a mail and ftp server, so that each account has ftp and mail. I don't want to run mail on 
me2.my-2-domain.com Linux box, which is my ns1.name server too.

I do in my db.my-1-domain.com files something like

my-1-domain.com.    in    SOA      ns.my-1-domain.com.   me1.my-1.domain
my-1-domain.com.    in    NS        ns.my-1-domain.com.
my-1-domain.com     in    MX 10  smtp.my-1-domain.com
my-1-domain.com     in    MX  20  smpt.my-ISP-domain.com.
my-1-domain.com.    in    A           a.b.c.67/27
ns.my-1-domain.com.in    A           a.b.c.67/27

pop                            in CNAME        my-1-domain.com.
smtp                           in CNAME        my-1-domain.com.
ftp                               in CNAME        my-1-domain.com.
mail                             in CNAME        my-1-domain.com.

Then I do in my db.d.c.b.a.-in-addr.arpa files something like

67.27.c.b.a.in-addr.arpa   in SOA     my-1-domain.com.   me.my-1-domain.com  
67.27.c.b.a.in-addr.arpa   in NS        ns.my-1-domain.com
67.27.c.b.a.in-addr.arpa   in NS        ns1.my-2-doamin.com
67.27.c.b.a.in-addr.arpa   in NS        ns2.my-ISPs-domain.com
67.27.c.b.a.in-addr.arpa   in PTR       my-1-domain.com

First question I have if the 67/27 notation is legitimite and if the 67.27.c.b.a.in-addr.arpa 
format is correct too. 

Second question I have if for my virtually hosted domain names on my first server.
Do I need to point mail and ftp aliases in the CNAME entries to their own domains 
or instead to the real domain of  the server which is my-1-domain.com 
under IP a.b.c.67

Would for example in db.my-15-domain.com  with IP a.b.c.82/27 this be correct ?

my-15-domain.com   in  SOA    ns.my-1-domain.com.  me.my-1-domain.com
my-15-domain.com   in  NS       ns.my-1-domain.com
my-15-domain.com   in  NS       ns1.my-2-domain.com.

my-15-domain.com.     in  A        a.b.c.82/27
ns.my-15-domain.com  in A         a.b.c.67/27    the ns server having IP 67
     (do I need above line at all ?)

my-15-domain.com       in  MX  10  smtp.my-1-domain.com
my-15-domain.com       in  MX   20  smtp.my-IPS-domain.com
     (my mail server on my-1-domain.com and a back-up mail server at my ISP?)

pop.my-15-domain.com.  in  CNAME    pop.my-1-domain.com.
ftp.my-15-domain.com     in  CNAME    ftp.my-1-domain.com..
smtp.my-15-domain.com. in  CNAME    smtp.my-1-domain.com  
mail,my-15-domain.com.   in  CNAME    mail.my-15-domain.com
                                                                     ^^^^^^^^^^^
Where should I point the mail alias to ? To the mail server's domain, which is my-1-domain ?
Or  to its own domain, which is my-15-domain. ?
Sorry for the long mail, I haven't read yet about setting up the mail and
ftp servers, but wanted to finish up with the ns server files. Is that round about
right.

I want my ISP just to be back-up for secondary name service and allow me
to to reverse mapping and do back-up mail service.

Thanks, Birgitt Funk