Comparison of Docker base mirror CENTOS6 and centos6.x

When writing dockerfile, the more commonly used base mirrors are centos. In the CentOS version, it is mainly divided into major and minor versions. The mirror versions currently provided by CentOS Docker are as follows: Latest, CENTOS7, 7 centos6, 6 centos7.4.1708, 7.4.1708 centos7.3.1611, 7.3.1611 centos7.2.151 1, 7.2.1511 centos7.1.1503, 7.1.1503 centos7.0.1406, 7.0.1406 centos6.9, 6.9 centos6.8, 6.8 centos6.7, 6.7 centos6.6, 6.6
such as CENTOS7/CENTOS6 is the main version, centos6.7/centos6.8 is the minor version. For a rolling build of a CentOS mirror, the official has the following statement: The CentOS Project offers regularly updated for all active images. These images is updated monthly or as needed for emergency fixes. These rolling updates are tagged with the major version. For Example:docker pull centos:6 or Docker pull Centos:7
Translated as follows: The CentOS project provides periodic updates to all releases. These mirrors are updated on a monthly or emergency repair basis. These rolling updates are marked with only the major version number. Like "Docker pull Centos:6" or "Docker pull centos:7."

The official description of the minor version number is as follows: Additionally, images with minor version tags, this correspond to install media are also. These images don't recieve updates as they are intended to match installation ISO contents. If you are choose to use this images it is highly recommended this include RUN yum-y update && yum clean all in Your dockerfile, or otherwise address any potential security concerns. To use this images, please specify the minor version tag:for Example:docker pull centos:5.11 or Docker pull
The translation is as follows: In addition, the image of the minor version number is also provided. These mirrors do not receive updates because they are intended to match the contents of the installation ISO. If you choose a mirror image of these minor version numbers as the base image, it is highly recommended that you add "RUN yum-y update && yum clean all" to the dockerfile, or locate any potential problems. Using these mirrors, specify the following tag for the minor version number: "Docker pull centos:5.11" or "Docker pull centos:6.6".

Therefore, according to Docker's official recommendation, it is recommended that you use the major version number CENTOS6,CENTOS7 as the underlying mirror, rather than using this version of centos6.7.