hostnamewindows
If I get the fully qualified computer name on a Windows server (2K3 or 2K8) using the GetComputerNameEx() API call, can I rely on that name to be unique on that particular domain? That is, can I assume that only a single active physical or virtual machine will have that fully qualified name at a given time?
As a second question: is it guaranteed that all Windows machines will have such a fully-qualified name?
Your hostname is the name of your computer.
Your fully qualified domain name is your hostname plus the domain your company uses often ending in .local.
So if the name of your computer is bob, and your company's domain is contoso.local, your computer's fully qualified domain name (FQDN) is bob.contoso.local.:
bobcontoso.combob.contoso.com.In the case of a domain like contoso.local I did not use an "external" internet domain name. This name doesn't have to be the only way that you address the server.
If you make it available by its IP address you can use DNS or that IP address to allow external users to access it.
The dot at the end of the FQDN is used to indicate the empty top-level domain.
Some more information on DNS:
Edit: Thanks for the comment on .local domains RobM
Best Answer
A properly functioning Windows Active Directory domain will not allow two computers with the same FQDN to exist within it.
All Windows computer joined to a domain will have a FQDN that includes the Active Directory domain(s) that make up its location in the forest.It might be possible to change the FQDN of a domain member by changing the primary DNS suffix usingnetdom computername /Add:andnetdom computername /MakePrimary:It may also be possible to changeHKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Paramaters\Domainmanually. This will require further testing to see if it's possible to alter a PC's FQDN away from a domain's heirarchy while it is still a member.