I'm aware that it is good to run
yum update from time to time to keep my Centos server updated, and I even see that there is way to automate this update. My question is, is it necessary to restart the server after the update? Is it a good idea? What happens if I keep updating and never restart?
So from the answers, I believe it is correct to say that I need to restart the server if the Kernel, libc, glibc has been updated. Alternatively use KSplice.