Docker Container FAQ


This blog post covers a brief overview of the topics covered and some common questions asked on Day 1 and Day2 Live Interactive training on Docker and Kubernetes Certification i.e. CKA / CKAD  and CKS.

This post will help you to learn Docker & Kubernetes and prepare you for these certifications and get a better-paid job in the field of Microservices, Containers and Kubernetes.

Through this CKA training program. first, we covered the concepts of Microservices and then we move ahead with Introduction to Docker and Containers. After covering these basic topics, we started with the Docker architecture, Installing Docker on VM and Docker Images. we also covered the first five labs for docker and Kubernetes.

Monolithic and Microservice

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img1We started our training with Monolithic & Microservice Applications, in this we explain different type of deployment methods for applications, what is the monolithic applications and drawback of it, how we can solve these drawbacks using the microservice deployment, what is the difference between Monolithic & Microservice Application, why we are using microservice type application deployment for Kubernetes.

FAQs asked in the session are:

Q1) What is the difference between Microservices architecture and Monolithic architecture.

Ans: A Monolithic Application is built as a single unit that combines the user interface and database into a single program running on a single platform. A monolithic program is self-contained and unrelated to other computer programs.

Advantages of Monolithic application.

  • Easy to Deploy.
  • It can be Scaled with Little Effort.
  • Easy to Test.
  • Development is Easy.

Microservices is an architectural design for developing a distributed application using containers. Microservices get their name from the fact that each function of the program runs as a separate unit. This model enables each service to scale or upgrade independently without interfering with other resources in the framework.

Advantages Of Microservices

  • Every service can be independently scaled.
  • It can be deployed independently.
  • It allows each service to be built separately by a team dedicated to that service.
  • It lowers the barrier to introducing emerging technology because developers are free to select whatever technologies make sense for their service rather than being restricted to the choices made at the outset of the project.

To know more about the Monolithic v/s Microservices

Q2) Is Microservices is only for E-Commerce applications?

Ans: No, We can use it with Many of the services. Net flix is one of the good examples of microservice.

Q3) Is Containers are based on N-Tier Architecture. Also, Microservice is a must for containers?

Ans: No, Container and N-Tier Architecture(monolithic) are different terms. We can use a container to deploy an N-tier application. The microservice application can be deployed without containers.

Q4) Only Microservices applications are for Containers. What about larger applications, I mean more CPU more RAM more storage, those are not for Containers?

Ans: Yes we can, Containers are used to deploy any type of application, it can be small or large. Each application is running through different microservices inside its own container. You can even limit CPU & RAM in a container.

Introduction to Docker and Container

After going through the basics of Monolithic & Microservice Applications, we started to discuss Docker and Container, Docker is a containerization platform that is used to create a container. We can deploy our application into the Container through an image. In this topic, we covered Docker, How to install docker in Virtual machine, why docker is a better option, and how to deploy a container using the docker image.

If you are new to the docker watch video on the Docker Tutorial for Beginners: 5 Hour Full Course [Hands-On Labs]

FAQ’s asked in the session are:

Q5) Is Docker Engine and Hypervisor are used for the same purpose?

Ans: No, they are used for a different purpose. A hypervisor is a kind of emulator, it is computer software, firmware or hardware that creates and runs virtual machines(VM). On the other hand, Docker Engine runs Inside virtual machines(VM).

To know the difference between VM and Container (Docker) Read our blog post

Q6) Can you please explain in Docker how the Thin OS is sufficient to run diverse App?

Ans: In docker thin OS means only the necessary packages are available in the OS at the time of image creation we define which packages we want in our OS to run the application and unnecessary packages not available in OS so the size will automatically decrease.

Q7) What is thin layer OS?

Ans: Thin OS is used by the containers. It is a thin OS that provides only support to run a container. It will not provide a highly orchestrated environment as of OS. Example of the thin layer is OS RedHat CoreOS, VMware Photon and RancherOS.

Q8) What is Containerized Application?

Ans: A containerization is a form of operating system virtualization in which programs are run in an isolated user-space called containers while sharing the same operating system (OS). A container is a fully packaged and compact computing environment.

Q9) What is Namespace?

Ans: Namespaces provide isolation for running processes, limiting their access to system resources without the running process being aware of the limitations.

Docker Uses the following namespace:

  • PID – It is Used for Process Isolation.
  • NET – It is Used for managing Network Interface.
  • IPC – It is Used to isolate IPC resources.
  • MNT – It is Used for filesystem mount.
  • UTS – It is Used for Isolating Kernel and version Identifiers.

 

Q10) What is SELinux?

Ans: Security-Enhanced Linux(SELinux) is a Linux kernel security module that provides a mechanism for supporting access control security policies, including mandatory access controls. SELinux is a set of kernel modifications and user-space tools that have been added to various Linux distributions.

Q10) What is SELinux?

Ans: Security-Enhanced Linux(SELinux) is a Linux kernel security module that provides a mechanism for supporting access control security policies, including mandatory access controls. SELinux is a set of kernel modifications and user-space tools that have been added to various Linux distributions.

Q11) Can we have multiple Container?

Ans: Yes, you can have multiple containers for a single application.

Q12) Can we run Linux OS Container inside Windows OS and in Reverse also?

Ans: Yes, you can use a Linux container in windows or a windows container in Linux. To run the container in different operating systems, OS must support container applications running inside the container.

Q13) Is Container is the product of Docker?

Ans: No, Container is not a product of Docker. A container is a standard unit of software that packages up code and all its dependencies so the application runs quickly and reliably from one computing environment to another.

To Know More about Docker Container.

Docker Installation & Architecture

Through these topics, we are Going to Install Docker In Virtual Machine. In our Session, we demonstrated Installing Docker on a Ubuntu machine Using Azure Cloud Resource.

Docker is available for download and installation on Windows OS, Linux, and macOS. You can choose any of the following Machine to Install Docker.

To know how to install docker on your machine read our blog on Docker Installation.

Q14) What do you mean by Docker daemon?

Ans: A context loop that handles Docker images, containers, networks, and storage volumes. The Docker daemon is the one listening for Docker API requests and processing them.

Q15) What is seccomp?

Ans: Secure computing mode (seccomp) is a Linux kernel feature. You can use it to restrict the actions available within the container. seccomp allows a process to make a one-way transition into a “secure” state. In seccomp only limited system calls are possible for example exit(),sigreturn(),read() and write().

seccomp is covered in detail in our Certified Kubernetes Security (CKS) training program, register for this FREE Class to know more about CKS & How to prepare for the exam.

Docker images

A Docker image is a read-only template containing instructions for building a container that can run on the Docker platform. It offers an easy way to package up the software and preconfigured cloud environments that you can use privately or openly with other Docker users.

To know more about the docker image Read our blog post

Q16) What is the difference between Docker Registry and Repository?

Ans: A Docker repository is where you can store one or more versions of a specific Docker image. An image can have one or more versions (tags) and a registry is a place where it stores a collection of repositories.

Q17) Can I have multiple images inside a container.

Ans: Yes, you can have multiple images inside a single container.

Quiz Time (Sample Exam Questions)

With the CKA training program, we are going to cover 100+ sample exam questions to help you prepare for CKA certification.

Check out one of the questions and see if you can solve this.

Ques)What command should you run to see all running container in Docker?

A. $ docker ps

B.$ docker rm

C.$ docker sudo

D.$ docker add

Comment your answer in the comment box.

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Next Task For You

To know about what is the Roles and Responsibilities of Kubernetes administrator, why you should learn Docker and Kubernetes, Job opportunities for Kubernetes administrator in the market, and what to study Including Hands-On labs you must perform to clear the Certified Kubernetes Administrator (CKA) Certification exam by registering for our FREE Masterclass.

Click on the below image to Register for our FREE Masterclass Now!



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