RE: [ActiveDir] Multiple Domain Trees in a Single Forest

[Grillenmeier, Guido]

I'd actually have to say that this is a battle worth fighting because people would try to see something in AD which they shouldn't => a separate tree should certainly not be used simply to put an organisational structure in place which is negative to the business in the longrun. Neither applications which are deployed forest-wide nor the stakeholders who are currently voting for a multi tree forest are really gaining any added value out of this structure - all it does is looking good on paper or a presentation-slide showing some sort of seggregation which doesn't really exist.   As joe very well points out, there are basically no benefits for the end-user (who couldn't care less about the name anyways) and you'd merely have even more administrative burdon on those who have the responsibility to keep your AD forest running.   So if you can't win the fight to keep everything in a single domain (which more than anything else should be the first goal), I'd at least put in the extra effort to keep all domains in a single domain tree in a forest. Certainly a battle worth fighting.    Even better, go for a single domain and do everything via OU structures - I've not found many good arguments recently NOT to use a single domain. Different password policies are certainly not a good one (the domain with the weakest policy in the forest defines your pw-related security). Better use a good overall PW policy and add smartcards for those accounts you want to have added protection. Replication sometimes crops up and could be a reason depending on which data you need onsite in some remote offices - but you should first discuss if you want these sites to have a DC in the first place and then (more often than not) for multi-domain forests you'll want a GC - so what's the point.... Administrative Isolation is definitely not a good one (won't start the list of reasons for this) Better division of _responsibilities_ for Backup/Restore as "the different orgs are responsible for their own data" is one of the worst reasons I've heard recently - not good, not good... - keep it central! A rare reason I did just have recently and had no argument against was the technical neccessity to have the same logonnames (samAccountName) for different regions of an outsourcer, due to some legacy dependencies to a regionally split host system which used these names.  Won't go into details here, but this did actually require multiple domains although the customer would have loved to make it all work in a single one...   /Guido From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Rick Kingslan Sent: Sonntag, 31. Juli 2005 17:38 To: ActiveDir@mail.activedir.org Subject: RE: [ActiveDir] Multiple Domain Trees in a Single Forest Joe said: “WHY??? What do you feel the benefit is?”   In my experience, it’s been not what *I* think the benefit is – it’s more about what management WANTED for reason A, or reason B, or whatever whacked business justification that they had.   I’m not much into creating trees for the heck of it.  However, it does interest me to a) keep my job b) try to convince people that this is purely a business decision, and technically I can provide an invisible ‘separation’ if that’s what they want.   However, as in all business – there is a time to make a decision.  Fight or not.  In the cases that I’ve had to implement additional trees, I’ve allowed it to happen because it wasn’t a battle worth fighting.  However, I pushed to get the tree merged back into the main tree as time and emotions settled.   Sometimes, joe – the only benefit of doing something that you don’t find palatable is because it’s not technically bad enough to warrant the fight that will ensue.   Rick From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of joe Sent: Saturday, July 30, 2005 2:49 PM To: ActiveDir@mail.activedir.org Subject: RE: [ActiveDir] Multiple Domain Trees in a Single Forest   I seriously dislike multi-tree forests. They tend to confuse support admins and some programs just aren't written properly for them and break. For instance I have the domain joe.com, what is the DN for my configuration container? Well you would like to assume cn=configuration,dc=joe,dc=com, however, you look at the rootdse and see that it is actually cn=configuration,dc=someotherdomainname,dc=local. A properly written program or script will work fine with either but that is a hell of an assumption, I still run across scripts and programs that try to parse the domains out to figure out DNs. When you bring in new people to work on your environment, it is silly to have to train them on such silly decisions as it is one more thing that they have to keep in mind that is special for your company.   The main question I like to ask people when they propose a multiple tree forest structure[1] is WHY??? What do you feel the benefit is? It has nothing to do with your email address. It has nothing to do with your userPrincipalName for logon. NetBIOS names can be A whether you have A.root.com or A.com. So what, besides making your support staff have to work harder and recall special things is the purpose behind having multiple trees?   On the LDAP searching part. I have seen programs that assume that the forest root DN is where you can base a GC search and get everything in the forest. This is of course incorrect and can cause failures in multi-tree forests. This is easily corrected by using the null base for the full forest search.   Every time I have encountered a desire for a multitree forest it has been the result of political infighting or an architect that really doesn't understand the product and thinks they are getting something that they aren't. I had one guy once tell me that any admin at the top of a domain tree automatically had full admin rights on every domain in the tree hierarchy... I actually had to get up and walk out of the room for a moment to decide if I really wanted to get too involved with that deployment because heaven knows what other decisions were made on knowledge that was also that wrong. Instead of working out implementation details, it required a complete review of the entire architecture and to understand the end goals. A completely different thing than what I was there for.     joe       [1] Which this is, a disjoint namespace is a different thing. You can have two different disjoints in the name space. The first is between the NetBIOS and DNS names of the domain - say the domain joe.com has a NetBIOS name of UncleBob. The second is on the DNS Suffixes used on the clients. For instance a client of bob in the domain joe.com would normally have a FQDN of bob.joe.com but in a DNS Suffix disjoint could have something like bob.sanfran.cali.joe.com or even bob.somethingelse.local.       From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Thursday, July 28, 2005 7:25 AM To: ActiveDir@mail.activedir.org Subject: [ActiveDir] Multiple Domain Trees in a Single Forest Hello All,     Looking to decide on an AD domain structure in a single forest. The options on the table are; 1.      Dedicated root domain (x.com) and child domains (i.e. a.x.com, b.x.com etc.) based on the regions. 2.      Dedicated root domain (x.com) and other domains (i.e. a.com and b.com etc.) based on the regions. The potential risk for the second option that has been identified is that the deep LDAP search against a regular DC instead of a GC in one domain for a resource in the another domain may not return any results. However, the client intends to take the risk and mitigate it by deploying enough Global Catalogs (GC). In a nutshell, we would like to go with a disjointed namespace for the multiple domains within the forest.  However, I need pro\cons to this approach.  In addition, does the introduction of conditional forwarding and stub zones mitigate many of the issues that plauged disjointed namespaces?   Thanks!   Rob