Question

We have a domain with full name, e.g. long-domainname.com; this domain name is replaced with alias short. this alias can be retrieved using netapi32.dll, like this:

[DllImport("Netapi32.dll")]
static extern int NetApiBufferFree(IntPtr Buffer);

// Returns the domain name the computer is joined to, or "" if not joined.
public static string GetJoinedDomain()
{
    int result = 0;
    string domain = null;
    IntPtr pDomain = IntPtr.Zero;
    NetJoinStatus status = NetJoinStatus.NetSetupUnknownStatus;
    try
    {
        result = NetGetJoinInformation(null, out pDomain, out status);
        if (result == ErrorSuccess &&
            status == NetJoinStatus.NetSetupDomainName)
        {
            domain = Marshal.PtrToStringAuto(pDomain);
        }
    }
    finally
    {
        if (pDomain != IntPtr.Zero) NetApiBufferFree(pDomain);
    }
    if (domain == null) domain = "";
    return domain;
}

This method return the sort value. But using the System.DirectoryServices.ActiveDirectory.Domain class, and its Name property, I get long-domainname.com value. Searching the properties under the Debug mode, I couldn’t find any short value field or property. Is it possible with System.DirectoryServices.ActiveDirectory.Domain class? Or may be it is possible with some other class of System.DirectoryServices namespace? How to get the short domain name value without importing external *.dll?

Answer 1

private string GetNetbiosDomainName(string dnsDomainName)
    {
        string netbiosDomainName = string.Empty;

        DirectoryEntry rootDSE = new DirectoryEntry("LDAP://RootDSE");

        string configurationNamingContext = rootDSE.Properties["configurationNamingContext"][0].ToString();

        DirectoryEntry searchRoot = new DirectoryEntry("LDAP://cn=Partitions," + configurationNamingContext);

        DirectorySearcher searcher = new DirectorySearcher(searchRoot);
        searcher.SearchScope = SearchScope.OneLevel;
        searcher.PropertiesToLoad.Add("netbiosname");
        searcher.Filter = string.Format("(&(objectcategory=Crossref)(dnsRoot={0})(netBIOSName=*))", dnsDomainName);

        SearchResult result = searcher.FindOne();

        if (result != null)
        {
            netbiosDomainName = result.Properties["netbiosname"][0].ToString();
        }

        return netbiosDomainName;
    }