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Get Global Catalog from DNS

Posted by: | March 18, 2012 | No Comment |

One option for finding global catalog servers is often overlooked – DNS.  In an AD environment DNS stores the SRV records that advertise the services domain controllers can deliver

$dnsserver = "dc02"            
Get-WmiObject -Namespace 'root\MicrosoftDNS' -Class  MicrosoftDNS_SRVType `
-ComputerName $dnsserver -Filter "ContainerName = 'Manticore.org'" |             
Where {$_.OwnerName -like "_gc*"} |            
select TextRepresentation

We are interested in the ‘root\MicrosoftDNS’ name space and the MicrosoftDNS_SRVType records. We want the manticore.org zone and all records where the Ownername is like “_gc*”

The results look like this

_gc._tcp.Site1._sites.Manticore.org IN SRV 0 100 3268 dc02.manticore.org.

_gc._tcp.Site1._sites.Manticore.org IN SRV 0 100 3268 server02.manticore.org.  
_gc._tcp.Manticore.org IN SRV 0 100 3268 dc02.manticore.org.  
_gc._tcp.Manticore.org IN SRV 0 100 3268 server02.manticore.org. 

under: DNS, PowerShell and Active Directory, PowerShell and WMI