Member Avatar for Jebcrack

Using VM workstation 9. I have setup 2 domain controllers each running exchange 2010.one has IP 192.168.1.1 and the other 192.168.2.1.exchange is running fine and the users in the respective domains can email each thru outlook.but the problem is; how do I route the 2 networks to have users email across the domains.I tried to configure 2 servers as routers but am stuck.. This my school project. Guys help:-)

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  • Latest Post Latest Post by CimmerianX

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Short, practical checklist to get the two subnets talking and Exchange delivering between them (builds on ’s routing idea and ’s DNS/MX point).

Create the networks and a router VM

  • In VMware Workstation’s Virtual Network Editor create two separate host-only networks (one per subnet) and attach each DC/Exchange VM to the correct VMnet.
  • Build a dedicated router VM (Windows with RRAS or a small appliance like pfSense) with two NICs — one in each VMnet. Give the router static IPs (example: 192.168.1.254/24 and 192.168.2.254/24). Avoid turning a domain controller into the router in anything but a lab; running Exchange on DCs is also not recommended outside a lab.

IP/gateway/routing

  • Set each server’s default gateway to the router IP on its subnet (or add a persistent static route pointing at the router). This makes the subnets routable without touching NAT.
  • Enable IP routing on the router VM (RRAS: enable LAN routing; pfSense does this by default when interfaces are configured).

Exchange and DNS specifics

  • Ensure each mail domain has internal DNS records: an A record for the Exchange host and an MX pointing to that A record (internal DNS on your DCs). Exchange will use DNS MX lookups to find the other server. If not using DNS, create a Send Connector that targets the other server’s IP (smart host). Open TCP/25 on the Exchange hosts and any intermediate firewall/router.

Quick troubleshooting checks

ping 192.168.2.1
tracert 192.168.2.1
nslookup -type=mx setup2.com
telnet 192.168.2.1 25

Check Windows Firewall inbound rules, Exchange Receive Connector remote IP restrictions, and Exchange Queue Viewer/message tracking for delivery failures. These steps will let mail flow between 192.168.1.0/24 and 192.168.2.0/24 once routing and DNS (or send connectors) are correctly set.

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Member Avatar for JorgeM

You can create a router using one additional VM running windows server with two NICs. One NIC on each subnet. Enable RRAS, no special router are needed since the networks will be local to the RRAS server

Then configure the hosts on each subnet with their default gateway address which will be the interface of the RRAS server on their subnet.

Here is a video on how to set this up: Enable LAN Routing on Windows Server 2008 R2

Edited by JorgeM
Member Avatar for CimmerianX

Routing is just step 1. You do need to have the something act as the router.... plenty of ISOs for linux based systems as well if you don't want to follow JorgeM's good advice.

After which, you need to setup DNS with the proper MX records so that each exchange server for setup1.com and setup2.com can find the Mail handler for the other domain. user@setup1.com emails user@setup2.com, setup1.com must be able to run a lookup for the MX of setup2.com to find the mail server to service email for that address.

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