I know that, run level=0  =>     Halt/Shuts down systemrun level=1  =>     Single-User Moderun level=2  =>     Multi-User Moderun level=3  =>     Multi-User Mode with Networkingrun level=4  =>     Undefinedrun level=5  =>     level 3 + display managersrun level=6  =>     Rebootwhat I am interested to know is,What is the difference in both the configurations for httpd service?  (additional general description is fine)Is it a good practice to use all run levels for a particular service?and anything important that one should to know about?Thank you
linux run levels: what is impact of running a httpd service on 35 and on 0123456
rhel;apache httpd;runlevel
Generally the httpd service will not distinguish between the different run levels, with the exception that it will only be started in some of the levels.chkconfig --list httpdshould list which levels the the httpd service will be running under.As to which levels to run under.  This really does not matter much since most machines spend 99.9% of their life at a single runlevel.(Docs)