code: def determine_hostname(display_name=None):
      
      if display_name:
          # if display_name is provided, just return the given name
          return display_name
      else:
          socket_gethostname = socket.gethostname()
          socket_fqdn = socket.getfqdn()
  
          try:
              socket_ex = socket.gethostbyname_ex(socket_gethostname)[0]
          except (LookupError, socket.gaierror):
              socket_ex = ''
  
          gethostname_len = len(socket_gethostname)
          fqdn_len = len(socket_fqdn)
          ex_len = len(socket_ex)
  
          if fqdn_len > gethostname_len or ex_len > gethostname_len:
              if "localhost" not in socket_ex and len(socket_ex):
                  return socket_ex
              if "localhost" not in socket_fqdn:
                  return socket_fqdn
  
          return socket_gethostname
docs: Find fqdn if we can