JN0-213 Cloud Associate (JNCIA-Cloud) Questions and Answers

In OpenShift, the worker node is used to host your application containers1. Worker nodes are where all your coding adventures happen, and they can be virtual or physical1. References from Juniper site: IBM Developer

The Docker component that builds, runs, and distributes Docker containers is dockerd. Dockerd is the persistent process that manages containers. Docker uses different binaries for different tasks. For example, it uses the docker binary for CLI commands and dockerd for the daemon process.

A CN2 controller communicates with CN2 vRouters using XMPP (Extensible Messaging and Presence Protocol) and with other CN2 controllers using BGP (Border Gateway Protocol). XMPP is used for control plane communication, while BGP is used for routing updates between controllers.

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

The name of the Docker container runtime is containerd, which is a daemon that manages the complete container lifecycle of its host system, from image transfer and storage to container execution and supervision to low-level storage to network attachments and beyond. Dockerd is the Docker daemon that acts as the primary user interface for Docker. Docker cl is not a valid name for any Docker component. Cri-o is another container runtime that implements the Kubernetes Container Runtime Interface (CRI) to enable using OCI (Open Container Initiative) compatible runtimes

The term that identifies to which network a virtual machine interface is connected is the virtual network ID (VNID). The VNID is a unique identifier assigned to each virtual network. It is used to differentiate between different virtual networks and to ensure that each virtual machine interface is connected to the correct network.

 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.

A vRouter uses virtual routing and forwarding (VRF) instances to create individual routing tables for each tenant. A VRF is a logical partition of a router’s routing table that allows multiple instances of routing information to coexist on the same router. A vRouter can provide connections to multiple tenants’ VMs by using different VRFs for each tenant

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.

The Kubernetes object definition file is in YAML format789. Kubernetes objects are represented in the Kubernetes API, and you can express them in .yaml format7. You can execute kubectl get deployment -o yaml to get the deployment definition in a yaml format8.

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 a cloud-native microservices-based architecture, the various modules of an application communicate through application programming interface (API) calls5. Each service is autonomous and self-contained and runs a unique process6. References from Juniper site: Microsoft Learn, Palo Alto Networks

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

MPLSoUDP (Multiprotocol Label Switching over User Datagram Protocol) and VXLAN (Virtual Extensible LAN) are two protocols that provide tunneling in the overlay and support multipath capabilities45. MPLSoUDP is an encapsulation protocol that allows MPLS packets to be encapsulated in UDP packets. VXLAN is a network virtualization technology that attempts to address the scalability problems associated with large cloud computing deployments

Overlay virtual networks are virtual logical networks constructed on top of an existing network using network virtualization technologies45. They decouple network services from the physical networking and interconnection technologies on the underlay network45. Two true statements about overlay virtual networks are:

• Overlay virtual networks work well on an IP spine-and-leaf topology6. They can be created over underlay networks using network virtualization technologies4.
• Overlay virtual networks allow both Layer 2 and Layer 3 communication65. They can serve not only different services (such as multiple departments) of the same tenant but also different tenants4. References from Juniper site: Microsoft Learn, Huawei IP Encyclopedia, Network Insight

To run a container in a Kubernetes environment, you should define a YAML manifest for the container and its resources2. YAML manifests are used to define Kubernetes objects, such as pods or services. These manifests describe the desired state of the system2.