Are you well-versed in Container deployment and how Host machine resources are utilized? Test your knowledge by answering these 10 questions.

In the realm of IT operations and DevOps, the true measure of an application’s performance lies in its production environment. Achieving smooth deployments requires a deep understanding of container host machines.

Containers, the workhorses of modern application deployment, abstract applications from the underlying hardware. They encapsulate application code along with all the necessary libraries and components, making it possible to run the application on various operating systems. For developers, this means they can focus solely on designing the application, without being concerned about the specifics of the host machine. However, IT administrators don’t have it quite as easy.

Their role involves deploying containers that communicate seamlessly, scale efficiently, maintain consistent application performance, and seamlessly update with new application code. The performance of the host machine plays a pivotal role in this process.

This 10-question quiz is designed to evaluate your knowledge of container host machines, ranging from the fundamentals to crucial aspects like network setup and resource allocation. Sharpen your skills and test your expertise!

Question 1

What is a host machine?

A. The set of policies that governs where and how a VM, container or other logical unit of code runs
B. A software supervisor that divides workloads among computing resources based on utilization rates or prioritization rules
C. The physical computing resources upon which an application, VM, container or other logical unit of code runs
D. A gracious robot that serves drinks and initiates small talk at any size function

Answer

C. The physical computing resources upon which an application, VM, container or other logical unit of code runs

Explanation

Whether virtual, containerized or even serverless, every computing workload runs on hardware. Servers — whether a single-U pizza box in a rack or a massive mainframe — are host machines for applications. Through various networking and virtualization strategies, organizations may present a pool of resources from multiple hosts to workloads.

In some situations, such as infrastructure as a service (IaaS) deployments, host machine will refer to a virtual host. This is the set of resources that the cloud administrator sees available for their workloads from the IaaS provider.

Question 2

Containers that share a host can always talk to each other.

A. True
B. False

Answer

B. False

Explanation

Containers are isolated by default. It is possible to run multiple containers for multiple applications on one host. However, to take advantage of communications speed, operations teams should deploy containers that work together in close proximity, in the same cluster or on the same host.

Question 3

Which of the following OSes can run as a Docker container host?

A. Alpine Linux
B. Red Hat Atomic Host
C. Windows Server 2016
D. All of the above
E. None of the above

Answer

D. All of the above

Explanation

Docker containers run natively on multipurpose Linux OSes, such as SUSE Linux Enterprise Server; pared-down OSes targeting small footprints, such as Alpine Linux and Boot2Docker; and on Linux OSes designed for containers with Docker functionality baked in, such as Red Hat Atomic Host. While containers originated in Linux, Microsoft created native Docker host machine capability in the Windows Server 2016 and Windows 10 OSes. Windows Server also comes in smaller-footprint designs with Server Core and Nano Server.

Question 4

Because containers don’t virtualize an OS like a VM does, administrators cut down on ­______.

A. Hybrid cloud architectures
B. Application performance monitoring
C. Host machine resource consumption
D. Details in the programming language of the application

Answer

C. Host machine resource consumption

Explanation

One of the main arguments for containerization from the sys admin side of the IT organization is reduced overhead for applications. A host machine typically runs more containers on given resources than VMs, because each VM includes a full OS — sometimes, a rather resource-heavy one.

But just because containers don’t encapsulate the OS doesn’t mean they are strictly low consumers of resources. A container has no defined resource limits until administrators impose them through the configuration. Docker enables the container administrator to set hard resource limits or soft limits, wherein the container can consume endless amounts of memory, for example, until a negative condition, such as memory content, occurs.

To avoid overwhelming a host machine, IT ops must understand their application workloads over time, any additional resource demands — such as a VM layer that underpins the containers — and container management settings and utilities available to allocate resources. The planning discussions between developers and operations, wherein resource expectations are set, are as critical for containerized apps as for those running in VMs or on bare metal.

Question 5

This kind of network (above) is installed by default with Docker Engine and creates a private network on the host machine.

A. Round robin
B. Overlay
C. Bridge
D. Macvlan

Answer

C. Bridge

Explanation

The Docker bridge network is a simple setup suited to pilot and proof-of-concept deployments, as well as development. Containers connected to a bridge network are isolated from containers on another network, but the user can allow external access by exposing ports. Other native Docker Engine network drivers include overlay and Macvlan.

Question 6

Docker container hosts can be bare metal, VMs or cloud. Which of the following statements is NOT true?

A. Enterprises concerned about compliance or new modes of operations can run Docker containers on VMs using virtualization management technologies.
B. Bare-metal containerization provides the most economical use of resources compared to hosting containers on VMs.
C. Public cloud providers offer containers as a service, which package management tooling with containerization technology.
D. Docker containers can run on any OS, including Windows Server 2008 and other older versions, so long as the host machine is Docker-compatible.

Answer

D. Docker containers can run on any OS, including Windows Server 2008 and other older versions, so long as the host machine is Docker-compatible.

Explanation

Application code and libraries packaged into a container rely on the OS kernel. Docker has expanded its supported OS list in the Enterprise Edition, but that does not mean that every OS fits the bill. Windows containers did not exist until Windows Server 2016, and older Microsoft OSes will not run them. The underlying hardware resources are not specified as Docker-compatible or container-ready, because containers are abstracted from hardware by the OS. This is a departure from hypervisor-based virtualization, wherein the hypervisor creates resource allocations for each VM that look to the application like complete servers. Administrators can mix bare metal, virtualization and containerization in the data center or cloud to meet specific goals and needs.

Question 7

What role does a registry play in the relationship between container images and host machines?

A. The container registry stores immutable container images, preventing changes and configuration drift from occurring in live production environments.
B. The registry validates that a container image meets compliance and security goals through randomized vulnerability attacks.
C. Container images maintain a network connection to their source registry, where stateful data for the application is stored.
D. The registry of moving virtualization (RMV) holds containers for an interminable amount of time before they obtain licensing information and updates.

Answer

A. The container registry stores immutable container images, preventing changes and configuration drift from occurring in live production environments.

Explanation

Registries store container image files and can be public or private. A container image includes all the necessary information for a software package to run on its host machine and OS. Updates to the live production hosts are made in these images, which Docker pulls from the registry. Registries host images in repositories, typically organizing all the versions of one image together in one repo.

A registry isn’t absolutely necessary, however. Paige Bernier, a software engineer on New Relic’s internal Demotron team, which simulates users with buggy systems, spins up container images on the host system with Docker Compose. “We’re sending up the app with the Dockerfile and building and starting the container on its host itself,” she said, because the particular use case doesn’t need to scale. Without a registry, Demotron’s engineers circumvent the steps of image versioning, builds and registry access management.

Registries are useful to share images with other team members or external users and to clamp down on image customization that can occur. Registries get the right image version deployed on all nodes, maintaining an immutable configuration at scale.

Question 8

Enterprise IT organizations that want to run containers on public cloud host systems must use the as-a-service (aaS) container management offering of the vendor, such as Amazon Web Services (AWS) EC2 Container Service (ECS).

A. True
B. False

Answer

B. False

Explanation

Major public cloud providers each offer a containers as a service (CaaS) hosting feature: AWS ECS, Google Container Engine (GKE) and Microsoft Azure Container Service (ACS). These managed environments use container scheduling technology to optimize resource utilization from the host VMs. The offerings vary — GKE relies on Kubernetes, while AWS ECS builds on Blox — and are rapidly evolving to attract enterprises that want to run containerized applications but don’t have built-up expertise in container cluster and host management. While an aaS choice creates some vendor lock-in for users, the degree of choice varies from vendor to vendor. For example, ACS users tie their containerized fate to Microsoft’s cloud resources but pick from Kubernetes, Apache Mesos (DC/OS) or Docker’s swarm mode for container management technology.

While cloud providers expect enterprises to follow the CaaS path, there’s nothing to stop a savvy administrator from designing and implementing an independent container provisioning and management system atop cloud host machines. Collaboration and troubleshooting software maker Atlassian built a Kubernetes infrastructure on AWS, for example, with compliance at the forefront. Tools such as Kubernetes Operations — known as Kops — ease the difficulty of getting container clusters up and running on AWS.

Question 9

Which three design elements will best help applications scale effectively in containers?

A. Privileged access and autoscaling host machines and containers
B. Microservices and autoscaling host machines and containers
C. Microservices and privileged access on a firewalled private cloud
D. Monolithic architecture, autoscaling host machines and Kubernetes APIs

Answer

B. Microservices and autoscaling host machines and containers

Explanation

Application containerization reaches a zenith of scalability and elasticity when the application is distributed into independent microservices, each of which is packaged in a container. The application’s architecture allows for only the in-demand components to scale up, saving on resource use and protecting performance. Containers often appear alongside the DevOps approach to an application lifecycle because they enable a partnership between developers and operations on scaling and resource consumption. The more logically an application’s code is distributed into microservices, the more efficiently operations teams can schedule, network and monitor containers.

Containerization abstracts the application from host machine resources more than ever before, but underneath it all, there is still hardware. As the application’s demand scales up, new container instances must appear — and new hosts as well — to supply the processing power and memory space users request.

Question 10

Container deployments must run inside VMs to achieve high availability.

A. True
B. False

Answer

B. False

Explanation

High availability is a concept implemented at every layer of an application deployment — from the power systems that keep data center server lights blinking to the structure of an app’s code. While many organizations choose to deploy containers into VMs — because virtualization management technologies and practices are well-understood and entrenched in the organization’s structure — VMs are just one way to ensure high availability. Docker Datacenter, for example, can replicate services across Universal Control Plane controllers on different hosts. Container setups with load balancing and resource monitoring also help distribute traffic to prevent crashes. An IT organization can use virtualization for high availability — and probably already does — but it is not required.

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