Question on # of child domains

  • Thread starter Thread starter Rick T
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R

Rick T

I would like to setup multiple child domains underneath a
root domain being used as a namespace holder. My question
is:

Is there an optimum number of second level domains that
can be added before proformance issues become a problem?

Can I install 10 child domains under the single domain?
25?

Thanks in advance for any opinions.
Rick
 
10 child domains is usually considered optimum. More
important are the number of domain controllers and the
pipeline between the DC's. As you add domain controllers
the KCC (Knowledge Consistency Checker) must keep up with
who has replicated what to whom. I have a client I am
helping right now that has 400 remote sites, each must
operate independently - IE: own DC. We are turning the KCC
off. The major drawback is if you plan to implement
software that requires schema mods (Ex: Exchange 2000, you
will need to make them prior to turning the KCC off. Also
keep in mind that most child domains are created to solve
office politics rather than having a distinct technical
need.
 
Every domain you add adds another entry to the logon dropdown list which is a pain. Also consider your global catalog
replication and size. At one point we had 9 child domains, we are slowly trimming this back as we realized it wasn't
needed and are down to 6 child domains now with one or possibly two more to be removed.
 
You probably won't have to turn off your KCC for 400 sites. I know what the docs say but that is for people who don't
take the time to properly set up their topology. Turn off site link bridging and set up good site links with proper
metrics and sites and replication schedules and you should be fine. We have well over 400 sites defined with hundreds of
domain controllers and the KCC is fine.

If you set it all up and you find the KCC keeps screwing the topology up, most likely you haven't configured something
properly. You can retry or turn it off and then see if you can do a better job manually.
 
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