Find Domin User Information

System.DirectoryServices class will help finding the information of a Domain User.

Function which will help retriving Active Directory Object:

       private DirectoryEntry GetActiveDirectoryObject(string filter, string domain, string[] properties)

            /// Running LADAP query to get the directory entry
            DirectoryEntry adsRoot = new DirectoryEntry("LDAP://" + domain, null, null, AuthenticationTypes.Secure);

            DirectorySearcher searcher = new DirectorySearcher(adsRoot);
            searcher.SearchScope = SearchScope.Subtree;
            searcher.ReferralChasing = ReferralChasingOption.All;
            searcher.Filter = filter;

            SearchResult result = searcher.FindOne();
            DirectoryEntry directoryEntry = result.GetDirectoryEntry();

            return directoryEntry;

        Parameters one has to pass to GetActiveDirectoryObject funtion:

string filter = string.Format("(&(ObjectClass={0})(sAMAccountName={1}))","person", username);

string domain = Current User's Domain

string[] properties = One can pass string array of properties, for Example: string[] properties = new string[] { "memberOf" };

Retriving data from the DirectoryEntry object:

      DirectoryEntry directoryEntry = GetActiveDirectoryObject(filter, domain, properties);
      if (directoryEntry != null)
                    directoryEntry.AuthenticationType = AuthenticationTypes.None;
                    string displayName = directoryEntry.Properties["displayName"][0].ToString();
                    string firstName = directoryEntry.Properties["givenName"][0].ToString();
                    string lastName = directoryEntry.Properties["sn"][0].ToString();
                    string email = directoryEntry.Properties["mail"][0].ToString();

I have also attached the sample code. For more information on the System.DirectoryServices please refere MSDN, it has detailed description about it.