All major system log files are located in the /var/log directory in Centos Linux. Below is a list of the standard log files that are located on a clean Centos install along with a short description.

cron — Logs for all cronjobs that are run on the server
dmesg — Logs from dmesg program which is used to examine or control the kernel ring buffer.
lastlog — The binary log that contains all of the last login information. (Type “last” to view)
messages — System logs from syslogd
mysqld.log — Logs from the mysqld process
secure — Access logs from the sshd process
yum.log — Logs from system updates via yum