How to get Domain Name (pre-Windows 2000) from FQDN (Fully Qualified Domain Name) using C#

By | August 6, 2010

This started when I saw a question on stack overflow and it challenged me to solve it, it may look simple initially but least to say it was challenging.  The question was about getting a list of all domain names in your network and display it in a friendly way like what you see when you log on to windows rather than

All you have to do is to refer to a COM Reference called Active DS Library which contains the IADsNameTranslate  interface which can translate distinguished names (DNs) among various formats.

Now having that tool, its just a matter of getting a list of domain which I can get in FQDN format easily by Getting the DomainCollection from the Forest you are in, now the last issue is converting that FQDN to a DN  format which is easy by using String Methods, we are doing this as the reference I mentioned above can only convert from other formats which is defined here and FQDN is not an option so the easiest would be DN. And here is how I did it.

using System.DirectoryServices.ActiveDirectory;
using ActiveDs;

private void ListDomains()
 string sUserName = "xxxx";
 string sPassword = "xxxx";

 DirectoryContext oDirectoryContext = new DirectoryContext(DirectoryContextType.Domain, sUserName, sPassword);

 Domain oCurrentDomain = Domain.GetDomain(oDirectoryContext);
 Forest oForest = oCurrentDomain.Forest;
 DomainCollection oAddDomainsInForest = oForest.Domains;

 foreach (Domain oDomain in oAddDomainsInForest)

private string GetName(string sDomainName)
 IADsADSystemInfo oSysInfo = new ADSystemInfoClass();
 IADsNameTranslate oNameTranslate = new NameTranslateClass();

 string[] aSplitDN = sDomainName.Split(new Char[] { '.' });
 string sDistinguishedName = "";

 //Convert Domain Name to Distinguished Name
 foreach (string sDomainPart in aSplitDN)
 sDistinguishedName = sDistinguishedName + "DC=" + sDomainPart + ",";

 oNameTranslate.Set((int)ADS_NAME_TYPE_ENUM.ADS_NAME_TYPE_UNKNOWN, sDistinguishedName.Remove(sDistinguishedName.Length - 1));//Remove the last comma
 string sFriendlyName = oNameTranslate.Get((int)ADS_NAME_TYPE_ENUM.ADS_NAME_TYPE_NT4);
 return sFriendlyName.Replace(@"""");
 return "Access Denied";

If theres an easy way just let me know, but for now this works for me!

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