When people install programs without fully realizing what they are doing, bad things tend to happen. Installing Exchange can be a tedious process – it has so many prerequisites that it can take several hours just to get to the point that exchange actually starts to install.

As we all know, Exchange 2007 requires a 64bit operating system. At least it’s required in a production environment since Microsoft will not support 32bit 2007 servers. We also know that Exchange 2007 does not read from the Global Catalog if the GC is running on a Windows 2000 Server. The newest Exchange requires a minimum of 2003 standard in order to read fully from Active Directory. And we all know that AD is required for Exchange to be happy. These are things we know.

If you open the Exchange Management Console and navigate to Server Configuration. In the main reading pane you should see your Exchange Server(s). Right click on your Exchange Server and select properties. The bottom two text boxes will show you the current Domain Controller(s) and Global Catalog(s). If you have more than one Domain controller and Exchange is only showing one, you have a problem.

First thing to check is always the Eventviewer. Check the eventvwr!!!
Second thing to check is if you can ping your DC from the Exchange Server, and that you can ping your Exchange Server from your DC.
Third thing is to run the command “dcdiag” on the DC not showing up in Exchange:
Start - Run - CMD - dcdiag - press enter
IF all of those pass with flying colors, you can add the DC and GC manually to Exchange using the PowerShell.

PowerShell Fix Steps:

On the Exchange Server, open the Exchange Management Shell.
set-exchangeserver -identity Name_Of_Server -staticDomainControllers ‘dc.domain.com’, ‘dc2.domain.com’
set-exchangeserver -identity Name_Of_Server -staticglobalcatalogs ‘dc.domain.com’, ‘dc2.domain.com’

IMPORTANT NOTE!!!
the Name_Of_Server MUST BE the name of your server. If you named it exchange07, use that name!
the ‘dc.domain.com’ MUST BE the FQDN Fully Qualified Domain Name of your server. If the servername is exchange07, the FQDN would be something like exchange07.mydomain.local!

Then recheck in the Exchange Management Console to verify that the GC and DCs are properly imported.

If you ever need to remove the additions:
get-exchangeserver -identity Name_of_server -staticdomaincontrollers $NULL
get-exchangeserver -identity Name_of_server -staticglobalcatalogs $NULL
After roughly 15 minutes, the “real” GC and DC’s should be populating. If not, check the eventviewer!

ARP, or Address Resolution Protocol, is the primary method for your computer to talk with other network devices. Basically, your computer has an IP address (192.168.1.100) and wants to talk with your email server (192.168.1.101). Your computer will send out an ARP request for the owner of 192.168.1.101. A message will come back saying that 192.168.1.101 has a MAC address of xx-xx-xx-xx-xx-x1. That’s basically how they communicate. It obviously gets a lot more tedious when you add gateways, routers, and switches to the mix. Then add internet devices too with different masks. Oh man!

But there is a problem – broadcast addresses are always the last available IP in a subnet (in our example it’d be 192.168.1.255 with a mac address of FF:FF:FF:FF:FF:FF). Gateway addresses are always the first available IP in the subnet (once again, 192.168.1.1). If someone wanted to poison the ARP cache, they could easily point to the gateway address and spoof everyone else on the network to believe that they’re the gateway.

Computer: Hi everyone, I’m looking for the gateway
Poison: I’M THE GATEWAY!!!
Poison: I’M THE GATEWAY!!!
Computer2: Hi everyone, I’m looking…
Poison: I’M THE GATEWAY!!!
Computer2: … for the gateway
Poison: I’M THE GATEWAY!!!

You can see why the poisoning of ARP can actually work. The poison programs will flood the network with broadcasts saying I’M THE GATEWAY!!!

So, how do you protect against this? The easiest way is to push a startup script to all your machines that deletes the current ARP and puts a static route in for your gateway. The only problem with this approach is if you ever change gateways or switches – the MAC address you enter as the static ARP will no longer be valid, and the routing for internet will cease.

Windows 2000/XP/Vista:

Start -> Run -> CMD
arp -d
arp -s 192.168.1.1 00-18-00-18-00-18

-d is for delete
-s is for static
obviously put your own gateway IP address in there and MAC address. If you need to find it, you can type arp -a and locate the MAC address associated with your gateway.

Vista requires elevated privs to run the arp commands. Right click on your command prompt and that will help with many of the problems.

Vista may require the following:

netsh -c “interface ipv4”
set neighbors “Local Area Connection” “192.168.1.1” “00-18-00-18-00-18”

Then check to make sure with:

arp -a