Juniper JN0-213 Cloud Associate (JNCIA-Cloud) Exam Practice Test

This manifest is used to create a deployment, which is a Kubernetes resource that manages a set of pods with the same configuration. A deployment can also provide declarative updates, scaling, and rolling back for the pods. The created pods are not receiving traffic on port 80, because the manifest does not specify a service or a selector for the deployment. A service is another Kubernetes resource that defines a logical set of pods and a policy to access them. A selector is a label query that matches the pods that belong to the service. Four pods are created as a result of applying this manifest, because the manifest specifies replicas: 4 in the spec section of the deployment

The default container runtime engine used by OpenShift is cri-o. CRI-O is an open source, community-driven container engine. Its primary goal is to replace the Docker service as the container engine for Kubernetes implementations, such as OpenShift Container Platform3.

Overlay networks are indeed virtual networks. They are logical constructs that stitch together disparate, dispersed network infrastructure, often referred to as underlay1. Underlay networks refer to the physical network infrastructure, while overlay networks implement network virtualization concepts2. References from Juniper site: Baeldung on Computer Science, PacketFabric, Cisco, HPE Aruba Networking

The forwarding plane (also known as the data plane) of a software-defined networking (SDN) controller is responsible for forwarding data packets based on the instructions given by the control plane23. It handles all activities involving data packets sent by the end-user, including forwarding of packets2. References from Juniper site: GeeksforGeeks, SDxCentral

In computer science, hierarchical protection domains, often called protection rings, are mechanisms to protect data and functionality from faults and malicious behavior. Rings are arranged in a hierarchy from most privileged (most trusted, usually numbered zero) to least privileged (least trusted, usually with the highest ring number). On most operating systems, Ring 0 is the level with the most privileges and interacts most directly with the physical hardware12. References from Juniper site: Wikipedia, GeeksforGeeks, Notes

 KubeVirt is a Kubernetes add-on that allows you to run and manage legacy virtual machine workloads alongside container workloads within a Kubernetes deployment. According to the KubeVirt website, KubeVirt is “a virtual machine management add-on for Kubernetes” that “aims to provide a common ground for virtualization solutions on top of Kubernetes”. Other Kubernetes add-ons that are mentioned in the question are Canal, which is a network policy provider that combines Flannel and Calico; ADOT, which is a distribution of the OpenTelemetry Collector that supports tracing and metrics collection for AWS services; and Romana, which is a network and security automation solution that supports multiple network topologies and policies.

he free -h command in Linux displays the total amount of free and used physical and swap memory in the system, as well as the buffers used by the kernel89. The cat /proc/meminfo command displays real-time information about the system’s memory usage as well as the buffers and shared memory used by the kernel1

A Kubernetes deployment is a resource object in Kubernetes that provides declarative updates to applications. It allows you to describe an application’s life cycle, such as which images to use for the app, the number of pods there should be, and the way in which they should be updated1. Two reasons to create a Kubernetes deployment rather than work with pods directly are:

• A deployment ensures that the desired number of pods is running at all times1. If a pod crashes, the Deployment will automatically re-create it.
• A deployment simplifies pod updates and roll-outs1. It allows you to describe a desired state in its specification and the Deployment controller changes the actual state to the desired state at a controlled rate1. References from Juniper site: Kubernetes Documentation

In Juniper Cloud-Native Contrail Networking (CN2), isolated namespaces are used to isolate a pod from other pods without explicitly configuring a network policy3. Pods in an isolated namespace can only communicate with pods in the same namespace3. They cannot reach pods or services in other isolated or non-isolated namespaces3.

 This technique allows multiple isolated user-space instances to be created by the host operating system. Unlike full virtualization, where the entire system’s hardware is emulated, OS-level virtualization shares the host’s operating system kernel but isolates the application processes12.

Network Functions Virtualization (NFV) is a network architecture concept that uses IT virtualization technologies to virtualize entire classes of network node functions into building blocks that may connect or chain together to create communication services3. The NFV framework explains how Virtual Network Functions (VNFs) fit into the whole solution4. The NFV Infrastructure (NFVI) is a component of NFV that consists of the infrastructure components —compute, storage, networking—on a platform to support software4. References from Juniper site: Red Hat, VMware, Wikipedia

Docker containers are designed to be ephemeral, meaning they run based on their current configuration. When a Docker container is stopped, it does not automatically save changes made during its runtime. When you execute docker run, it starts a new instance of the container, not an existing version with its changes[14-16]. If you want to persist changes between runs, you need to commit changes to a new Docker image or use Docker volumes for data persistence[14-16]. References from Juniper site: Stack Overflow, Docker Docs

An overlay network is a virtual network that is built on top of another network. Nodes in the overlay network are connected by virtual or logical links, each of which corresponds to a path, perhaps through many physical links, in the underlying network45. For example, distributed systems such as peer-to-peer networks and client-server applications often overlay their own network connections over the physical network connections provided by the Internet

The kubelet is a component of Kubernetes that runs on all nodes in the cluster and ensures that containers are running in a pod910. It takes a set of PodSpecs that are provided through various mechanisms and ensures that the containers described in those PodSpecs are running and healthy

Virtual networks are logical networks that are decoupled from the underlying network hardware. This decoupling allows network administrators to manage their networks independently of the physical network topology. As such, virtual networks can span multiple devices, allowing for a high degree of flexibility and scalability. Furthermore, virtual networks are available on common Linux distributions, allowing for easy deployment and management. 

OpenShift includes a preconfigured, preinstalled, and self-updating monitoring stack that provides monitoring for core platform components4. You also have the option to enable monitoring for user-defined projects4. This means OpenShift has its own monitoring framework (B) and is able to configure customized alerts (D). References from Juniper site: OpenShift Container Platform

Control groups (cgroups) is a Linux kernel feature that limits, accounts for, and isolates the CPU, memory, disk I/O, and network usage of one or more processes678. It allows you to allocate resources among user-defined groups of processes running on a system. You can monitor the groups of processes, deny the groups of processes access to certain resources, or even freeze groups of processes

The openstack user list command uses the Keystone service, which is the identity service for OpenStack. Keystone provides authentication, authorization, and service discovery for OpenStack. It also manages projects, users, roles, and endpoints for the OpenStack services