Multiple NICs on Exchange 2007

katredrum used Ask the Experts™
Hello Experts,

I have a single all role Exchange Server 2007 SP2 that has 4 NICs installed. I have configured each NIC as a internal private subnet.

Our network consists of 4 subnets to decrease the broadcast domain via VLANs on the switch. Some of my users are receiving Event ID 5000 showing up. When I researched Event ID 5000, it seems that Outlook is having trouble trying to send email.

Would having 4 internal NICs cause end users from having trouble sending emails? The server is not doing any routing. Each NIC acts as if it were on its own subnet.
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4 seperate NICs should not be an issue. From the user's workstation, make sure that you can resolve the Exchange Server through DNS. Then if that works, begin eliminating if the necessary ports are being blocked.


In DNS there are 4 host records for EXCH2007:
The workstations all can ping their respective subnet using the Exchange host name. I will check and purge DNS for outdated entries.
Assign Default Gateway to a single NIC. leave all other three's defauld gateway blank. This will fix the problem.
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How does Exchange know how to send email if say a user on subnet 192.168.3.X sends out email and only default gateway is
Exchange should try to send based on the nic that is assigned to the Gateway you specify. So make sure the default gateway you set up to use the .1.X net is the nic for that net.

I don't recomend multihomed installation's of services, simply because of the fact that DNS create's a problem in this scenario. (A record of the hostname consist of 4 ipadresses, which one does outlook use?)
i woul'd suggest using a single subnet for all your servers and using a router to divide your ip domains
This create's a SPOF, but that can be solved by a failback router

Hope this helps


Thanks for your input. The only reason why I wanted to use these ports is to have each subnet access the server without having to go throught the router. The router is already taxed with VOIP.
I understand why people do not configure multihomed servers. In my experience, DNS is fine when all services is up and running. It only causes a trouble when a connection goes down and usually then, the router is able to redirect to another interface on the same router so we are okay here with it.

Aha, so your router is maxed out with VOIP traffic now i understand your problem more clearly.
An other way to solve this is to configure each subnet with clients with a different configuration for outlook.
Let each subnet of clients connect to it's own exchange ip address in other words (client connects to instead of the hostname)
or, more maintanable, create a extra a-record (without creating a ptr record) exchange1,exchange2,exchange3,exchange4 and let the users connect to these hostnames.
If you assign Gateway to only one NIC, the rest of routes should direct using Static Routes

eg: route add mask metric 2 (Repalce xxx with matching net mask)

You can do the same for other two cards. This will sort the routing problem.

You can find more information about the static route adding in this article

Although this article for XP still you can use in server environment.

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