lsnrctl start or status command very slow need more than 3 mins can display result;

hi

   i meet a very strange problem:on the SUSE 10 OS and Oracle 11gR1 

   when problem happen run lsnrctl start or status or stop need more than 3 mins can display but the command is success;

   when is comment the file /etc/resovle.conf the lsnrctl command exeucte very quickly;

   i guess the lsnrctl need read file resovle.conf;

  who can tell me more information about lsnrctl and /etc/resovle.conf

  i check my listener.ora file the host use IP and /etc/hosts file is right;