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Writeable Domain Controller in AD site with Exchange RRS feed

  • Question

  • Hi Experts,

    When I run the ExBPA it will returns the following finding:

    "There were no writeable domain controllers found in Active Directory site 'my site name'. At least one writeable domain controller is required for Exchange to function properly."

    In my case, I have one AD-site where I have number of HUB servers. No mailbox nor CASes roles exist in there. Does anybody knows why the Exchange still requires writable DC and why it is not able to use the closest DC from the next site?

    Or is this again some generic answer when certain combinations are found?

    --

    Petri

    Tuesday, August 9, 2011 2:43 PM

Answers

  • The HT would like to do lookups for such things as routing decisions so a DC is required in that site. We can go all day on why it can’t be an RODC but Microsoft is a very big company and the left hand very often doesn’t know what the right hand is doing. I would say that if you don’t have a DC in that site there’s a pretty good chance the site (i.e. location) doesn’t need to be an AD Site in it’s own right. Obviously YMMV and circumstances you haven’t expanded on  take precedence but take a look, does that need to be a site? Remember that an AD site can be a larger subnet and the actual locations can be a smaller portion; i.e. the AD site could easily be a /16 and the physical sites could be a bunch of /24’s. (numbers made for illustrative simplicity only)
     
    "Petri X" wrote in message news:eabe702f-667e-49c7-8757-2d8a991eeda2...

    Hi Experts,

    When I run the ExBPA it will returns the following finding:

    "There were no writeable domain controllers found in Active Directory site 'my site name'. At least one writeable domain controller is required for Exchange to function properly."

    In my case, I have one AD-site where I have number of HUB servers. No mailbox nor CASes roles exist in there. Does anybody knows why the Exchange still requires writable DC and why it is not able to use the closest DC from the next site?

    Or is this again some generic answer when certain combinations are found?

    --

    Petri


    Mark Arnold, Exchange MVP.
    • Marked as answer by Jerome Xiong Tuesday, August 16, 2011 3:06 PM
    Wednesday, August 10, 2011 1:22 AM
  • It is really hard to say why we need at least one GC in every site.

    Just like we don’t know how every Exchange component works.

    As a general rule, designate at least one domain controller in each site as a global catalog server.

    Placing Servers into Sites


    • Marked as answer by Jerome Xiong Tuesday, August 16, 2011 3:06 PM
    Thursday, August 11, 2011 8:53 AM

All replies

  • The HT would like to do lookups for such things as routing decisions so a DC is required in that site. We can go all day on why it can’t be an RODC but Microsoft is a very big company and the left hand very often doesn’t know what the right hand is doing. I would say that if you don’t have a DC in that site there’s a pretty good chance the site (i.e. location) doesn’t need to be an AD Site in it’s own right. Obviously YMMV and circumstances you haven’t expanded on  take precedence but take a look, does that need to be a site? Remember that an AD site can be a larger subnet and the actual locations can be a smaller portion; i.e. the AD site could easily be a /16 and the physical sites could be a bunch of /24’s. (numbers made for illustrative simplicity only)
     
    "Petri X" wrote in message news:eabe702f-667e-49c7-8757-2d8a991eeda2...

    Hi Experts,

    When I run the ExBPA it will returns the following finding:

    "There were no writeable domain controllers found in Active Directory site 'my site name'. At least one writeable domain controller is required for Exchange to function properly."

    In my case, I have one AD-site where I have number of HUB servers. No mailbox nor CASes roles exist in there. Does anybody knows why the Exchange still requires writable DC and why it is not able to use the closest DC from the next site?

    Or is this again some generic answer when certain combinations are found?

    --

    Petri


    Mark Arnold, Exchange MVP.
    • Marked as answer by Jerome Xiong Tuesday, August 16, 2011 3:06 PM
    Wednesday, August 10, 2011 1:22 AM
  • The reason to have that site for the HTs was to keep client's email traffic away from these servers as they are tiny once :)

    But the message is pretty much like default message when Exchange server is site without DC.

    --

    Petri

    Wednesday, August 10, 2011 10:13 AM
  • It is really hard to say why we need at least one GC in every site.

    Just like we don’t know how every Exchange component works.

    As a general rule, designate at least one domain controller in each site as a global catalog server.

    Placing Servers into Sites


    • Marked as answer by Jerome Xiong Tuesday, August 16, 2011 3:06 PM
    Thursday, August 11, 2011 8:53 AM
  • Personally I like much more if some tools says: "no writable DC in the site" that there are some reasons why it is so. And I though here might be some how might have a deeper knowledge :)

    --

    Petri

    Thursday, August 11, 2011 8:06 PM