Help - Bind 9.3.2 use a lot of memory

[Alex Tang]

Hi All

I upgrade the cache only dns server  to bind 9.3.2. All of them is normal but it use a lot of memory, the named use 1.2G memory, is it normal ?

load averages:  0.41,  0.42,  0.43                                                dns3                                                16:27:54
38 processes:  36 sleeping, 1 stopped, 1 on cpu
CPU states: 80.2% idle, 14.3% user,  5.5% kernel,  0.0% iowait,  0.0% swap
Memory: 2.0G real, 281M free, 1.3G swap in use, 4.3G swap free

   PID USERNAME THR PR NCE  SIZE   RES STATE   TIME FLTS    CPU COMMAND
  7839 named      7 43   0  1.2G  1.2G sleep  26.4H    0 21.60% named

the  cleaning-interval is 3 days. 

i change it to default , reload the config by rndc and flush the database by rndc but the database size cannot decrease.

Is it normal ? Please help

thx very much