William Woods writes:
5.4 ? really???. 5.4 ? you have a lot of other issues to worry about.
Repeating it three times doesn't make an arrogant statement more true.
There are corporate environments that cannot upgrade for various reasons. Also, the history and performance of e.g autofs on RHEL/CentOS is truly awful. 5.4 does quite well in this regard, and later releases don't.
Obviously, there is no excuse for not upgrading Internet facing systems.