Cgroups (control groups) is a core Linux concept that reflects the ability to limit resource allocation to containers, such as CPU, memory, disk I/O, or network bandwidth. Cgroups can help prevent resource exhaustion scenarios on the Docker host due to a single application that is overconsuming available resources, as it can enforce quotas or priorities for each container or group of containers. Union filesystem overlay is not a core Linux concept that reflects the ability to limit resource allocation to containers, but a technique that allows multiple filesystems to be mounted on the same mount point, creating a layered representation of files and directories. Linux namespaces is not a core Linux concept that reflects the ability to limit resource allocation to containers, but a feature that isolates and virtualizes system resources for each process or group of processes, creating independent instances of global resources. Device mapper is not a core Linux concept that reflects the ability to limit resource allocation to containers, but a framework that provides logical volume management, encryption, or snapshotting capabilities for block devices. Verified Reference: https://www.comptia.org/blog/what-is-cgroups https://partners.comptia.org/docs/default-source/resources/casp-content-guide