Caveats when dealing with ifcfg files

Caveats when dealing with ifcfg files

What are certain "Gotcha's" when dealing with Linux's network service, and
configuring the corresponding ifcfg-* files?
for example one of the caveats I came across was:
Lot of time people take backup of configuration file in same folder with
appending '.bak' for indicating that it is backup. But ini- tialization
scripts load all ifcfg-* files on boot and hence even ifcfg-eth0.bak will
get loaded and may interfere with configura- tion specified in ifcfg-eth0
file.
Anything else someone just starting out with Linux's network service
should know, look out for?
(I'm using/dealing mostly with CentOS and Fedora (RHEL-style systems I
guess))