# yum update
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: centosz3.centos.org
 * extras: centost5.centos.org
 * updates: centosb5.centos.org
Resolving Dependencies
--> Running transaction check
---> Package centos-release.x86_64 0:7-0.1406.el7.centos.2.3 will be updated
---> Package centos-release.x86_64 0:7-0.1406.el7.centos.2.4 will be an update
--> Finished Dependency Resolution

Dependencies Resolved

================================================================================================================
 Package                    Arch               Version                                Repository           Size
================================================================================================================
Updating:
 centos-release             x86_64             7-0.1406.el7.centos.2.4                updates              21 k

Transaction Summary
================================================================================================================
Upgrade  1 Package

Total download size: 21 k
Is this ok [y/d/N]: y
Downloading packages:
Delta RPMs disabled because /usr/bin/applydeltarpm not installed.
centos-release-7-0.1406.el7.centos.2.4.x86_64.rpm                                        |  21 kB  00:00:00
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Updating   : centos-release-7-0.1406.el7.centos.2.4.x86_64                                                1/2
  Cleanup    : centos-release-7-0.1406.el7.centos.2.3.x86_64                                                2/2
  Verifying  : centos-release-7-0.1406.el7.centos.2.4.x86_64                                                1/2
  Verifying  : centos-release-7-0.1406.el7.centos.2.3.x86_64                                                2/2

Updated:
  centos-release.x86_64 0:7-0.1406.el7.centos.2.4

Complete!