cPanel Forums

I have server with specification
core : 16
ram : 32 gb

total account in my whm :
113 account

my problem
i can not open all website in my whm account . when i access cpanel it shows up. example
open a.com -> fail
open a.com/cpanel ->success
open whm -> success
ping a.com from cmd -> success

what i have been trying
reboot apache -> still error
reboot mysql server-> still error
reboot server -> still error
tu off firewall -> still error

i hope you can help me. thank you