Maximum number of child domains

[Brian Bagley]

Is there any official information that states the maximum
number of child domains a single forest may have? I've
received some third-hand info that I'm not too sure about
that puts it around 130. It's been suggested that
having too many more domains would cause the structure to
collapse in on itself.

Does the number of domains increase with 2003?

 

[Simon Geary]

There is a limit to the length of an FQDN which in turn leads to a limit to
the number of child domains in any one tree. Check out this article.
http://support.microsoft.com/?id=245809

This only becomes a problem if you have lots of child domains in the same
tree, it does not apply if you have hundreds of different domain trees in
the same forest. I've not heard of any such limit although that's not to say
there isn't one..

 

[Jim Singh]

MS w2k had some restrictions including 5000 users per group, no. of domains
to 5000 (recomened was 500) and no. of sites you could have in w2k was
totally depending upon how many domain you have in the forest. Meaning, the
more domains the less sites you could have that is because the fact that KCC
process an algorithm to generate replication in w2k. Those algorithms have
been modified in 2k3 so the limit of no. domains has gone up from 5000, and
no. of domain controllers that you can have per domain has also gone up to
1000+. The users restriction in also no longer in place. MS has tested
having more than 5000 child domains and havent seen any KCC replication
degradation. Obviously, you need powerfull servers to hold this big of a
database and processing.

-Jim

 

[ptwilliams]

Some nice info. here that I'd not come across before. Can you point me in
the direction of the literature that talks about these limits please?

Also, the whole number of sites wasn't so much a limit for AD, it was just a
limit for the KCC. If you were to manually configure you're connection
objects you could have a lot more than the 100 mark. Like you've said, the
algorithm that does this has been simplified and is now more efficient; thus
the 100 auto-site limit has ceased (or at least been extended).

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MS w2k had some restrictions including 5000 users per group, no. of domains
to 5000 (recomened was 500) and no. of sites you could have in w2k was
totally depending upon how many domain you have in the forest. Meaning, the
more domains the less sites you could have that is because the fact that KCC
process an algorithm to generate replication in w2k. Those algorithms have
been modified in 2k3 so the limit of no. domains has gone up from 5000, and
no. of domain controllers that you can have per domain has also gone up to
1000+. The users restriction in also no longer in place. MS has tested
having more than 5000 child domains and havent seen any KCC replication
degradation. Obviously, you need powerfull servers to hold this big of a
database and processing.

-Jim

 

[Brian Bagley]

Could you point me to any documenation of Microsoft's
test of 5000 domains?