Rotating high CPU

On one of my servers the cpu is starting to jump, happend a 20 minutes ago.

I went into top and started watching what was going on; basically it was jumping between 3 programs;

Mysql
httpd
bind

all were jumping to 99% cpu.

I did a reboot of each system and check out my mail reports, things looked okay. I waited around 5 min and things looked okay after the reboot, then one by one they started jumping again.

Anyone have suggestions on the issue? Do you think its inbound or outbound?

I had a hunch it could be spam, but am not sure at this point. Do you think it could be an inbound attack?

Thanks for any suggestions.

 

 

 

 

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