How to prevent a second network interface from updating DNS with its IP address

I can't create the zone superwebsite.mycorp.com inside the intranet: this would cause the AD DNS server to consider itself authoritative and ignore the real authoritative server outside of the intranet.

You can, and that's the only way you're going to get what you want. I've had similar setups in the past, and as dirty as doing this will make you feel, I've never had issues doing it.

The key is to create a zone whose name matches the FQDN, superwebsite.mycorp.com, not for mycorp.com as a whole. Then create a new A record in the zone with the relevant IP.

The only time this will present a problem is:

• When the IP changes, you must remember to update it internally.
• If you ever use 4th level names, i.e. something.superwebsite.mycorp.com, you also need to maintain these both in the Internet DNS and the internal DNS.

DNS settings are incorrect. DNS IP's point to DNS servers, the terminology of "DNS gateways" is incorrect and misleading as DNS servers only respond to queries, they don't do any packet routing.

On Windows Server:
-In IPv4 TCP/IP properties change primary DNS server to 192.168.0.8 (no secondary DNS)
-Do an "ipconfig /registerDNS", reboot.

In DHCP server scope (currently this is the router):
-Change primary DNS server to be 192.168.0.8 (Windows Server IP)
-Do not use a secondary DNS server unless there is a 2nd AD DNS server on the LAN.

Note that w/ a Windows server in place then network browsing works better if DHCP is done on server & DDNS is enabled. See:
http://technet.microsoft.com/en-us/library/cc771255.aspx http://en.wikipedia.org/wiki/Dynamic_DNS#Function

Workstations:
Reboot or "ipconfig /renew" after above changes are completed.

Yes, if the Windows DNS server goes down then the internet is also down. If that's the case then there will be larger issues and the DHCP scope on the router can be enabled at that time.

Because AD depends on DNS internal workstations should only use internal AD DNS servers. Having an external 2ndary DNS will cause unpredictable browsing, logon and network performance issues in an AD domain.

Using a .com like BVOffice.com for an AD name is often problematic and not recommended IMO. Currently there are no public DNS records but if this is not your domain name then I would either buy it, but I would still change the internal AD name to bvoffice.local. Using .com for an AD name can be managed (mostly...) but requires a good understanding of DNS and TCP/IP.