Find any AD Server/Domain Controller within local Network

Find any AD Server/Domain Controller within local Network

Hello,

is there a way to find any AD Server/Domain Controller within local Network?

I set up an Domain Controller in Windows 2003 Server. I tried to find some 
Network API to search for AD Servers, but I didn't find any or what I found 
didn't work. I tried to use DsGetDcName, but without success. Result was always 
empty.

There must be a way, any ideas?

Regards,
Benjamin Kalytta

date: Fri, 04 Apr 2008 07:51:09 +0200 author: Benjamin Kalytta

Re: Find any AD Server/Domain Controller within local Network

If DsGetDCName doesn't work, there is likely something wrong with your DNS 
integration with AD.

Joe K.
-- 
Joe Kaplan-MS MVP Directory Services Programming
Co-author of "The .NET Developer's Guide to Directory Services Programming"
http://www.directoryprogramming.net
--
"Benjamin Kalytta"  wrote in message 
news:ft4fkr$l5r$01$1@news.t-online.com...
> Hello,
>
> is there a way to find any AD Server/Domain Controller within local 
> Network?
>
> I set up an Domain Controller in Windows 2003 Server. I tried to find some 
> Network API to search for AD Servers, but I didn't find any or what I 
> found didn't work. I tried to use DsGetDcName, but without success. Result 
> was always empty.
>
> There must be a way, any ideas?
>
> Regards,
> Benjamin Kalytta

date: Fri, 4 Apr 2008 08:34:41 -0500 author: Joe Kaplan

Re: Find any AD Server/Domain Controller within local Network

Hi Joe,

I made a call like this:

DsGetDcName(0, 0, 0, 0, DS_GC_SERVER_REQUIRED, &pdci)

The returned error is ERROR_NO_SUCH_DOMAIN.

In Network Settings I changed the DNS/Nameserver to the address of the DNS 
Server where DC is also running on. What could be the Problem here?

Regards,
Benjamin Kalytta

date: Sun, 06 Apr 2008 01:21:09 +0200 author: Benjamin Kalytta

Re: Find any AD Server/Domain Controller within local Network

Are you logged in with an account from the domain where you are trying to 
locate a DC?  If not, then you have to be if you don't want to supply a 
domain hint in your call.  If you are logged in with a domain account, then 
there is something wrong.  Getting NLTEST and using it to diagnose would 
probably be a good idea.

Joe K.
-- 
Joe Kaplan-MS MVP Directory Services Programming
Co-author of "The .NET Developer's Guide to Directory Services Programming"
http://www.directoryprogramming.net
--
"Benjamin Kalytta"  wrote in message 
news:uX6KEP3lIHA.5080@TK2MSFTNGP02.phx.gbl...
> Hi Joe,
>
> I made a call like this:
>
> DsGetDcName(0, 0, 0, 0, DS_GC_SERVER_REQUIRED, &pdci)
>
> The returned error is ERROR_NO_SUCH_DOMAIN.
>
> In Network Settings I changed the DNS/Nameserver to the address of the DNS 
> Server where DC is also running on. What could be the Problem here?
>
> Regards,
> Benjamin Kalytta
>

date: Sun, 6 Apr 2008 09:18:38 -0500 author: Joe Kaplan

Re: Find any AD Server/Domain Controller within local Network

> Are you logged in with an account from the domain where you are trying to 
> locate a DC?  If not, then you have to be if you don't want to supply a 
> domain hint in your call.

No, the client computer is even NOT joined to a Domain. Otherwise it wouldn't 
make any sense to search for a DC in local network if the client would already 
be joined.

Benjamin Kalytta

date: Mon, 07 Apr 2008 06:56:38 +0200 author: Benjamin Kalytta

Re: Find any AD Server/Domain Controller within local Network

Actually, it makes a lot of sense to search for a DC is the computer is 
joined.  That is actually how a computer FINDS a DC to talk to in the first 
place.  It doesn't happen by magic, it happens by a call to this API.

As I said before, it only makes sense to call DsGetDCName with a null domain 
hint parameter (DomainName) if the current security context is a domain 
account, as that gives the API something to bootstrap a domain name from. 
If the current account isn't a domain account, you must supply a domain name 
here.  When you ask for a GC, you have to specify the name of the forest 
instead.

Joe K.
-- 
Joe Kaplan-MS MVP Directory Services Programming
Co-author of "The .NET Developer's Guide to Directory Services Programming"
http://www.directoryprogramming.net
--
"Benjamin Kalytta"  wrote in message 
news:OREmOvGmIHA.1164@TK2MSFTNGP02.phx.gbl...
>
>> Are you logged in with an account from the domain where you are trying to 
>> locate a DC?  If not, then you have to be if you don't want to supply a 
>> domain hint in your call.
>
> No, the client computer is even NOT joined to a Domain. Otherwise it 
> wouldn't make any sense to search for a DC in local network if the client 
> would already be joined.
>
> Benjamin Kalytta

date: Mon, 7 Apr 2008 08:26:15 -0500 author: Joe Kaplan

Re: Find any AD Server/Domain Controller within local Network

> If the current account isn't a domain account, you must supply a domain name 
> here. 

Sorry to mither you again, but let me explain a scenario.

There is a large network with various Domain Controllers within. Just imagine 
there is a new PC connected to the network, the user or PC don't know anything 
about the network and just want to know if there is any Domain Controller within 
this network to connect with or do something with it. Also imagine that 
DNS/Nameserver is set up already pointing to one of the DNS Servers within 
network (whichs knows about DCs -> since there are DC specifies DNS Records)

So there must be a way to get any of the DC (Domain) without knowing a name or 
something. So what I think what DsGetDcName do is to do a kind of DNS Record 
Query to get DC specific records which returns a list of various DCs. But 
unfortunately it seems not to work.

The Query could look like:

Zones = DNSQueryGetZones(DNSServer, "_msdcs*")
foreach(Zone.Get("Domains") as Domain) {
     ... // Print all Domains
}

But I don't know if such queries are possible.

Regards,
Benjamin Kalytta

date: Mon, 07 Apr 2008 22:37:08 +0200 author: Benjamin Kalytta

Re: Find any AD Server/Domain Controller within local Network

There may be a way to scrub through DNS looking for SRV records that would 
indicate the presense of AD, but I'm not sure how to do that.  DsGetDCName 
can't bootstrap a DC without some sort of domain info to go by though.

If the environment you were in had more than 1 domain or there was more than 
one forest (which is typical in large networks), how would you know whether 
a DC you found was relevant to what you want to do?

I'd suggest asking this question again on the 
microsoft.public.windows.server.active_directory group to see if anyone else 
has any ideas on how you might be able to do this.

Joe K.
-- 
Joe Kaplan-MS MVP Directory Services Programming
Co-author of "The .NET Developer's Guide to Directory Services Programming"
http://www.directoryprogramming.net
--
"Benjamin Kalytta"  wrote in message 
news:u2K7n8OmIHA.5280@TK2MSFTNGP02.phx.gbl...
>> If the current account isn't a domain account, you must supply a domain 
>> name here.
>
> Sorry to mither you again, but let me explain a scenario.
>
> There is a large network with various Domain Controllers within. Just 
> imagine there is a new PC connected to the network, the user or PC don't 
> know anything about the network and just want to know if there is any 
> Domain Controller within this network to connect with or do something with 
> it. Also imagine that DNS/Nameserver is set up already pointing to one of 
> the DNS Servers within network (whichs knows about DCs -> since there are 
> DC specifies DNS Records)
>
> So there must be a way to get any of the DC (Domain) without knowing a 
> name or something. So what I think what DsGetDcName do is to do a kind of 
> DNS Record Query to get DC specific records which returns a list of 
> various DCs. But unfortunately it seems not to work.
>
> The Query could look like:
>
> Zones = DNSQueryGetZones(DNSServer, "_msdcs*")
> foreach(Zone.Get("Domains") as Domain) {
>     ... // Print all Domains
> }
>
> But I don't know if such queries are possible.
>
> Regards,
> Benjamin Kalytta

date: Mon, 7 Apr 2008 21:59:04 -0500 author: Joe Kaplan