FWIW this has served me very well when any new update comes out, whether there is a yum upgrade or not.
yum clean all yum update yum yum clean all yum update
or
yum check-update | more
and make choices later... etc
man yum
can help of course...
I tend to wait until the highest traffic is gone too unless there is something specific I need bug or security wise.
Also, it is a good idea to make wise use of your yum.conf and specifically the exclude= area (see below yum.conf file listing)
[main] cachedir=/var/cache/yum debuglevel=2 logfile=/var/log/yum.log pkgpolicy=newest exclude=clam* exim perl* postfix sendmail spamassassin distroverpkg=centos-release tolerant=1 exactarch=1 retries=20 obsoletes=1 gpgcheck=1
# PUT YOUR REPOS HERE OR IN separate files named file.repo # in /etc/yum.repos.d
- rh
-- Robert - Abba Communications Computer & Internet Services (509) 624-7159 - www.abbacomm.net