MySQL keeps crashing randomly - recent errors in error logs says this

160626 21:50:42 [Warning] IP address '113.108.21.*' could not be resolved: Name or service not known
160626 22:42:57 [Warning] IP address '124.172.137.*' could not be resolved: Temporary failure in name resolution
160626 22:43:10 [Warning] IP address '124.172.137.*' could not be resolved: Temporary failure in name resolution
160626 22:43:25 [Warning] IP address '124.172.137.*' could not be resolved: Temporary failure in name resolution
160626 22:43:41 [Warning] IP address '124.172.137.*' could not be resolved: Temporary failure in name resolution
160626 22:43:54 [Warning] IP address '124.172.137.*' could not be resolved: Temporary failure in name resolution
160626 22:44:09 [Warning] IP address '124.172.137.*' could not be resolved: Temporary failure in name resolution
160627  0:45:24 [Warning] IP address '117.79.84.*' could not be resolved: Name or service not known

In my.cnf are this lanes, which can resolve this somehow?

key_buffer              = 16M
max_allowed_packet      = 16M
thread_stack            = 192K
thread_cache_size       = 8
# This replaces the startup script and checks MyISAM tables if needed
# the first time they are touched
myisam-recover         = BACKUP
#max_connections        = 100
#table_cache            = 64
#thread_concurrency     = 10
#
# * Query Cache Configuration
#
query_cache_limit       = 1M
query_cache_size        = 16M

Server have CPUs with 20cores and 258450MB of RAM