Question : benefit of subdomains in active directory?

What's the benefit of having a subdomain in a active directtory network?  Let's say I have two locations...

New York
Indiana

Domain name of location NY would be: companyname.com
Domain name of location IN would be: in.company.com

Why is this better than say having both locations just use the same domain name?  

Thanks,
Bran

Answer : benefit of subdomains in active directory?

Well, actually your setup would be:

Domain:  companyname.com
Subdomain:  in.companyname.com

Regardless, they are in the same Forest, and you do not have to worry about creating Trusts, and all that that implies...

Actually, I just found a pretty good article explaining this and why (and when) to use subdomains..

http://www.samspublishing.com/articles/article.asp?p=32080&seqNum=6&rl=1