'Return the address of a nameserver.
TODO: Weight servers for response time so faster ones can be
preferred.'

def pickServer(self):

    if ((not self.servers) and (not self.dynServers)):
        return None
    serverL = len(self.servers)
    dynL = len(self.dynServers)
    self.index += 1
    self.index %= (serverL + dynL)
    if (self.index < serverL):
        return self.servers[self.index]
    else:
        return self.dynServers[(self.index - serverL)]
