Using DNS Services on an internal network and still using an outside DNS

Question

I have just started using Mac OSX Server for the first time and I am trying to set up an internal DNS server so I can set up an LDAP Directory master and replica. However, I am running into some problems in setting up the DNS server on our network.
This is where it gets a little confusing to me here and i have to explain some things. We have a shared web hosting ISP, which means that our mail services and web hosting services are not hosted on site. To access our mail services using a FQDN I would point Outlook to mail.xxx-xxx.net. However, I want to use that domain, xxx-xxx.net, as our internal network as well because it is the name of our company.
I can get all of the DNS names to propogate to their assigned IP's on the internal network and can ping everything using fully qualified domain names, but whenever I go to use services such as mail., it cannot find the server which is hosting that service because it is obviously not on our internal network. This makes sense that I cannot ping it, but how do I set up the alias mail.xxx-xxx.net to point to the ip address of the mail servers hosted by our ISP instead of something hosted on our internal network?
Sorry I can't clarify better, I'll try some cliff's instead;
1) Trying to set up internal dns server so I can use LDAP Directory Master and Replica Services.
2) The domain, xxx-xxx.net is currently being used for web hosting and mail services not hosted at our site.
3) Want to use the domain xxx-xxx.net as our internal domain because it is the name of our company, and eventually we will be hosting our own content.
4) Can set up internal DNS server and get all IP's to propagate just fine, but services such as mail.xxx-xxx.net cannot be used because they are not hosted on the internal network.
5) How do I set up DNS to point certain services to point to an external DNS servers, or to the IP address of the server itself so I don't have to use the ip address i.e. mail.216.256.33.24?

Answer 1

Ok I got it
Here's my walkthrough for all the other tormented souls, that might find this thread and require help:
Introduction:
Internet-card: ra0 192.168.16.64
Internet-gateway, nameserver 192.168.16.1
local-network-card eth1 192.168.15.1
[1] modprobe capabilty
   -> /etc/rc.conf
[2] pacman -S
   * dhcpd (DHCP daemon)
   * bind (Berkeley Domain Name Server)
[3] vi /etc/dhcpd.conf
ddns-update-style ad-hoc;
option domain-name "example.org";
option domain-name-servers ns1.example.org, ns2.example.org;
default-lease-time 600;
max-lease-time 7200;
subnet 192.168.15.0 netmask 255.255.255.0
# --- default gateway
option routers 192.168.15.1;
option subnet-mask 255.255.255.0;
option broadcast-address 192.168.15.255;
option domain-name-servers 192.168.15.1;
range 192.168.15.2 192.168.15.254;
default-lease-time 21600;
max-lease-time 43200;
[4] vi /etc/named.conf
acl micro
192.168.15.0/24;
options {
directory "/var/named";
pid-file "/var/run/named/named.pid";
auth-nxdomain yes;
datasize default;
allow-query{ micro; };
allow-recursion { micro; };
[5]
/etc/rc.d/dhcpd start
/etc/rc.d/named start
    -> rc.conf
[6] iptables
vi /etc/sysctl.conf
net.ipv4.ip_forward = 1
iptables -t nat -A POSTROUTING -o ra0 -j SNAT --to 192.168.16.64
iptables -A INPUT -j DROP -m state --state NEW,INVALID -i ippp0
iptables -A FORWARD -j DROP -m state --state NEW,INVALID -i ippp0
make it a script that is run in /etc/rc.local