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canonical: https://enum.co/learn
locale: en
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# Learn. Cloud concepts, explained.

Storage, Kubernetes, network and operations concepts in plain terms: what each one is, how it works and how enum runs it.

### Storage

- [What is S3 versioning?](https://enum.co/learn/what-is-s3-versioning) (updated 2026-10-18)
  S3 versioning keeps every version of an object in a bucket, so overwrites and deletes can be undone by restoring an earlier version.
- [What is S3 Object Lock?](https://enum.co/learn/what-is-s3-object-lock) (updated 2026-10-17)
  S3 Object Lock stores object versions as write-once-read-many (WORM), so a locked version cannot be overwritten or deleted until its retention period ends or its legal hold is removed.
- [What is erasure coding?](https://enum.co/learn/what-is-erasure-coding) (updated 2026-10-16)
  Erasure coding protects stored data by splitting it into data and parity fragments on different servers, so it can be rebuilt after some fragments are lost.
- [What is S3-compatible storage?](https://enum.co/learn/what-is-s3-compatible-storage) (updated 2026-10-15)
  S3-compatible storage is object storage that accepts the S3 API, so existing S3 tools, SDKs and backup software work after you change the endpoint and keys.

### Kubernetes

- [What is a CNI plugin?](https://enum.co/learn/what-is-a-cni-plugin) (updated 2026-10-19)
  A CNI plugin connects Kubernetes pods to the network: it creates each pod's interface, assigns its IP address and often enforces network policies.
- [What is a Kubernetes cluster upgrade?](https://enum.co/learn/what-is-a-kubernetes-cluster-upgrade) (updated 2026-10-18)
  A Kubernetes cluster upgrade moves the control plane and then the worker nodes to a newer Kubernetes version, one minor release at a time.
- [What is a node pool?](https://enum.co/learn/what-is-a-node-pool) (updated 2026-10-17)
  A node pool is a group of Kubernetes worker nodes with the same machine type and settings, managed as one unit for sizing, upgrades and workload placement.
- [What is the Kubernetes control plane?](https://enum.co/learn/what-is-kubernetes-control-plane) (updated 2026-10-16)
  The Kubernetes control plane manages a cluster's state through the API server, etcd, the scheduler and the controller managers. Worker nodes run pods; the control plane decides what runs where.
- [What is managed Kubernetes?](https://enum.co/learn/what-is-managed-kubernetes) (updated 2026-10-15)
  Managed Kubernetes is Kubernetes where a provider runs the control plane, etcd and upgrades, while you deploy and run your own workloads on the worker nodes.

### Network

- [What is a CAA record?](https://enum.co/learn/what-is-a-caa-record) (updated 2026-10-20)
  A CAA record is a DNS record that names which certificate authorities may issue TLS certificates for a domain, so other authorities refuse to issue.
- [What is DNSSEC?](https://enum.co/learn/what-is-dnssec) (updated 2026-10-20)
  DNSSEC adds digital signatures to DNS records, so resolvers can check that an answer came from the zone owner and was not changed on the way.
- [What is a DNS zone file?](https://enum.co/learn/what-is-a-dns-zone-file) (updated 2026-10-19)
  A DNS zone file is a plain text file that lists every record of a DNS zone, in a standard format nameservers load and providers import and export.

### Operations

- [What is vendor lock-in?](https://enum.co/learn/what-is-vendor-lock-in) (updated 2026-10-22)
  Vendor lock-in is the cost and effort that keeps you on one cloud provider, built up through proprietary APIs, provider-specific identity and the price of moving data out.
- [What are egress fees?](https://enum.co/learn/what-are-egress-fees) (updated 2026-10-21)
  Egress fees are per-gigabyte charges for data leaving a cloud provider's network, usually to the internet, while data coming in is typically free.
- [What is a cloud exit?](https://enum.co/learn/what-is-a-cloud-exit) (updated 2026-10-21)
  A cloud exit is the planned move of workloads and data off a cloud provider, onto another platform or your own servers, without losing data or service.