How do I connect a DUAL WAN router to 2 different networks?

I need to setup a DUAL WAN router (Cisco RV042) to connect to 2 different networks.
RV042 on WAN Port 1:
Broadband Wireless Cable Router:
DHCP enabled
DNS Server 1:
DNS Server 2:
Connected to cable Internet connection

RV042 on WAN Port 2:
Cisco VPN Router:
No DHCP, static IP range available: – 253
DNS Server 1:
DNS Server 2:
Connected via ADSL to OPTUS Network

RV042 LAN ports:
All computers on LAN need to access Internet via WAN Port 1 and OPTUS Network via WAN Port 2 (some of them are wireless clients only).

How can the DUAL WAN router be setup to allow access to both external networks on WAN 1 and WAN 2?
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vivigattConnect With a Mentor Commented:
I don't know this particular DUAL WAN router, but I configured some other Dual Wan routers in the past.

I assume that the router has a single "internal" IP address. This must be the "default gateway" for your clients.
So enabling static routes will be the easier thing to do.
Route to (default route) should be attached to WAN1
Route to the 172.16 network (or to the real subnet assigned to WAN2 interface if the VPN is beyond this interface) must be assigned to WAN 2 interface.

As Garry G mentioned, DNS might be an issue. With such configuration, I usually set a local (non authoritative) DNS, which forwards DNS requests to the appropriate DNS servers (based on the domain name in the request)

Now, there is something I don't get...
What is the "Broadband Wireless Cable Router:" about?

Garry GlendownConnect With a Mentor Consulting and Network/Security SpecialistCommented:
Check whether you can configure static routes on the RV042 ... if so, add a default route towards gateway and the route for the OPTUS network towards gateway The "smaller" OPTUS subnet is "more specific" than the default route to the internet, so IPs in that range will preferably take the WAN2 route, while all remaining routes remain towards the WAN1 link. Problem might be the DNS lookups, not sure whether you can do a decent DNS on the router, which will use the Optus DNS entries for certain TLDs, while using the internet DNS addresses for all other names ...
michelhumairAuthor Commented:
Thanks vivigatt and Garry-G. That makes sense.
The Broadband Wireless Cable router does not need to be on WAN 1 and can simply be used on a LAN port as a wireless Access Point. I don't fully understand how to setup the DNS. Can either of you please elaborate. Thank you.
I assume you have a MS Windows server, right?
This will be your DNS.
Install the DNS "role".
For Win2003:
For Win2008:

Your DNS server will need to have at least 2 zones. One per subnet.
Create the zones and the associated forward looking zones. Use the default settings all teh time.
For resolving the other DNS queries (the one that are not for hosts in your zones) you have to use forwarders:
The DNS server sends the DNS requests it receives to some other DNS servers.
To enable forwarders
on Windows 2003

How to Configure Forwarders
Windows Server 2003 can take advantage of DNS forwarders. This feature forwards DNS requests to external servers. If a DNS server cannot find a resource record in its zones, it can send the request to another DNS server for additional attempts at resolution. A common scenario might be to configure forwarders to your ISP's DNS servers.

    Click Start, point to Administrative Tools, and then click DNS.
    Right-click ServerName, where ServerName is the name of the server, and then click the Forwarders tab.
    Click a DNS domain in the DNS domain list. Or, click New, type the name of the DNS domain for which you want to forward queries in the DNS domain box, and then click OK.
    In the Selected domain's forwarder IP address box, type the IP address of the first DNS server to which you want to forward, and then click Add.
    Repeat step 4 to add the DNS servers to which you want to forward.
    Click OK.

On Windows 2008:

Your DNS server will serve ALL your client. They must then be configured to use it. If you have an Active Directory domain, the DNS server must also be a domain controller (actually, the first DNS server listed in a client IP config must be a DC)
If your client get their DNS servers address with DHCP, , configure the DHCP accordingly.

Then you have to make sure that each client is set to record its own entry in the DNS zones.
DHCP configuration is your best choice for that (otherwise you would have to configure each client individually.

If you are not familiar with DNS, it may take a little time before the setting is working as expected. But it should work correctly.
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