There are several ways to check what CentOS version is running on your linux VPS. Below are some examples of how to determine the CentOS version. The following command works with all CentOS versions.
How to Check OS Version in Linux
# cat /etc/redhat-release CentOS Linux release 7.3.1611 (Core)
How to check the kernel version
# uname -a Linux vps.linodelinux.com 4.9.15-x86_64-linode81 #1 SMP Fri M