2 nic, dynamic ip best practice ?

[dns-slacker]

Hi ppl,

Wut is the best design concept for 2 nic, dynamic ip ?
Am thinking to configure eth0 for resolving private IPs,
eth2 for zone mydomain.com.

Is it ok to run own primary dnsserver, while have the 2nd server
hosted by a ddns/public dns-server (I registered 1 by granite canyon).
Or should I have them both hosted by ddns/public dns server ?

In this case, how can I tell the 2nd dns server about my IP each time?

Can any one post an example of :
/etc/{hosts,resolv.conf}, named.conf, mydomain.zone ?

Am thanking in advands for possible helps ..