🌐 Domains
What is a domain?
First of all, what we have been calling an Active Directory network is what is usually known as a Domain. A domain is a set of connected computers that shares an Active Directory database, which is managed by the central servers of a domain, that are called Domain Controllers.
Domain name
Each domain has a DNS name. In many companies, the name of the domain is the same as their web site, for example etherdrake.com, while others have a different internal domain such as etherdrake.local.
PS C:\Users\User> $env:USERDNSDOMAIN
ETHERDRAKE.LOCAL
PS C:\Users\User> (Get-ADDomain).DNSRoot
etherdrake.local
Identify current user domain from Powershell
Identify current computer domain from Powershell
In addition to its DNS name, every domain can also be identified with NetBIOS name. For example, the domain etherdrake.local could have the NetBIOS name ETHERDRAKE. You can see the NetBIOS name being used in log in operations, where the user is identified with something like ETHERDRAKE\Administrator, where the first part is the NetBIOS name and the second one is the username.
Finally, a domain can be identified by its SID (Security Identifier). The SID is more used by programs (using the Windows API) than users, but you should know how to obtain it in case you require it.
PS C:\Users\User> Get-ADDomain | select DNSRoot,NetBIOSName,DomainSID
DNSRoot NetBIOSName DomainSID
------- ----------- ---------
etherdrake.local ETHERDRAKE S-1-5-21-1372086773-2238746523-2939299801
Get DNS name, NetBIOS name and SID of domain