is sub domain = child domain?


when I ran dcpromo, it's asking me if I want  to add it as a new domain tree or a child domain...
I'm not sure which one to choose.. What is a child domain?

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Is there another Domain Controller on the network. If not you have to set it up as a new domain.

If you have a domain already e.g. and you want to set up a another domain within that domain e.g. (for another office).. that will be the child domain
mikestevenAuthor Commented:
I'm trying to add a sub domain in ny ( to handle the emails for that address and then another in japan ( Does this mean I want the child domain option? so that I can only have 1 address book for the entire AD?

Creating both a new domain tree or a child domain will create a brand-new Active Directory domain, but within the same forest as your present domain.

Are you trying to simply promote another Domain Controller into your existing domain? If so, you need to back out of the dcpromo, start again, and choose the option 'Additional Domain Controller in Existing Domain'.

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You dont actually need a child domain. It really depends how you want to set it up. What tigermatt said above is correvt but you can also do the following

You can add the subdomain name into you recipient policy in Exchange and you will receive the emails as long as a DNS server is pointing MX records for the subdomain name to you Exchange server.
mikestevenAuthor Commented:

I have two locations new york and japan. I have the main DC ( in NY and now I want to join ( do I join it as a child? this will be handling our mail in NY.

then another will be in japan, to handle Having only 1 AD so it is centrally controlled...

3 servers
1 - Main DC -NY
1 - Mail - NY
1 - Mail - JP
mikestevenAuthor Commented:
but I want to have only 1 address book.

To create a subdomain, you'd need to use a child domain, yes.

However, a subdomain would probably be way over-the-top for what you describe. You could still achieve or email addresses using Exchange, without having to create separate child domains in Active Directory. Child domains will simply confuse the situation - and also mean that for resilience, you will need more servers running than you will ever need.

mikestevenAuthor Commented:

how can we get only 1 address book? if we have individual domains within one forest? is it still possible?

I'm still a tad confused why you're going down the multiple child domains route. How large is your network? How many users? If you don't have more than several thousand users, it would be more appropriate to retain a single-domain, single-forest environment, which is simply split up into separate Active Directory Sites. This is the best practice - it is perfectly acceptable to spread a single domain across multiple sites.

You might want to take a look at for information on the deployment of Exchange infrastructure across multiple domains. That link seems to suggest separate domains for different geographic locations is a good approach, but that would only apply if there are hundreds or thousands of users in each geographic region.

You would, however, be able to achieve a single GAL with recipients pulled from across all the child domains, if you went down this route.

mikestevenAuthor Commented:
is that possible on ms exchange 2000? to host two email addresses

Yes, you can have an unlimited number of email domains in Exchange. You'd simply need to configure the recipient policy accordingly, and configure the MX records to have inbound email hit the Exchange Server.

mikestevenAuthor Commented:
awsome, and how will the addressbook look like? can everyone see each other? ny and jp ?
mikestevenAuthor Commented:
but with this setup, I won't be able to setup exchange mode connection suing ms outlook for JP site...or there's a way to enable this in exchange 2000 thru the internet?
mikestevenAuthor Commented:
thanks much for the insight, now i have a better understanding. with this one AD & one ms exchange setup. Will I add this as a new domain controller or as a sub domain?

if with a new domain controller, then where will I add the new users? MainDC  server or where I installed MS Exchange server?

two servers
-Main DC
-MS Exchange (as new DC)
mikestevenAuthor Commented:
i hope u guys haven't abandoned me.

You'd simply add the DCs for the other sites as 'Additional Domain Controllers in an Existing Domain' (in the dcpromo wizard). You'd then need to create separate sites for each geographical location, and configure the appropriate subnets for each site in Active Directory Sites and Services:

Exchange can be deployed anywhere on the network. Each other site should have a direct hardware VPN, so Outlook could create a direct MAPI connection to Exchange.

Is there any reason why you're using Exchange 2000? There would be significant performance benefits if you used Exchange 2003/2007 with Cached Exchange Mode and all the other various features.


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