Docker Interview Questions and Answer Part – 15

Which fundamental networking technology does the native (local) overlay driver leverage when creating multi-host container networks?

• VLAN
• Token Ring
• VXLAN (Ans)
• FCoE

You need to create a singe container network that spans multiple hosts and gives all containers on the network IP addresses from the same L2 subnet.
Which built-in Docker networking driver would you use?

• bridge
• overlay (Ans)
• ipvlan
• l2-overlay

Which of the following commands would you use to display all networks present on a particular Docker host?

• docker networks get
• docker network ls (Ans)
• docker network display
• docker network show

In which of the following scenarios will the built-in Docker name resolution allow two containers to resolve each other by name?

• Two containers created with the –name flag and both containers are on the same container network (Ans)
• Two containers created with the –name flag and both containers are part of the same Swarm Service
• Two containers created with the –name flag and both containers are part of the same Swarm
• Both containers are on the same Docker host

You manage a production Docker estate and want to make sure all of the nodes in a particular Swarm can handle and process requests for a particular service. You
need this to work even if nodes in the Swarm are not running a task for the service. Which technology should you use to accomplish this?

• IPVLAN
• Service Discovery
• The Routing Mesh (Ans)
• An traditional external load balancer

Which of the following container networks is used by Swarm Mode for internal routing of traffic?

• overlay
• nat
• ingress (Ans)
• bridge

Which core Docker component contains the bulk of networking code and is the de facto implementation of the CNM?

• bridgenetwork
• containerbridge
• libnetwork (Ans)
• libcontainer

Which of the following describes a sandbox in the context of Docker networking?

• A container within a container that contains a shared network stack
• A ring-fenced area of the Host OS that contains an isolated network stack (Ans)
• An area of virtual memory used as scratch space by Libnetwork
• A ring-fenced area of a container made available to all other containers on the same network

In which programming language is Libnetwork written?

• C
• Pascal
• Python
• Golang (Ans)

You have a container network called m1-prd that is scoped to “swarm.” However, when you are logged onto a node in the Swarm, you cannot see the network. Why
might this be the case?

• The node you are logged onto is not running a task that is using the network, so the network has not been extended to the node yet. (Ans)
• Docker takes a lazy approach to creating networks on all nodes in the Swarm. You probably haven’t waited the 30 minutes it takes to infect the entire Swarm
  with the network.
• The m1-prd network is encrypted and therefore not visible in the output of regular docker network commands.
• The docker network ls command does not display networks scoped to to “swarm.”

What is the purpose of the MACVLAN driver?

• To put containers on existing networks and VLANs
• To create multi-host overlay networks
• To enhance container networking for Docker Engines running on Docker for Mac (DFM) (Ans)

Which of the following open source specification documents forms the foundation of Docker networking?

• The Docker Network Model (DNM)
• The Container Network Interface (CNI)
• The Container Network Model (CNM) (Ans)
• Virtual Extensible LAN (VXLAN)

Which of the following are the three major constructs defined in the Container Network Model (CNM)?

• Container, endpoint, network
• Sandbox, endpoint, network (Ans)
• Service, endpoint, network
• Sandbox, container, network

Which native Docker feature simplifies and enhances creation and management of Docker networks?

• The Docker Remote API
• Content Trust
• The volume driver interface
• Swarm Mode (Ans)

Which of the following will display the specific command that created each layer in an image?

• docker build -th imagename
• docker history imagename (Ans)
• docker search imagename
• docker images -t imagename

What is accomplished by running the following command?
docker run -p 5000:5000 registry:latest

• Docker Engine will run a “hot update” on the live Registry image.
• The Docker Registry image will (if necessary) be pulled and then run, exposing port 5000. (Ans)
• Only if the Docker Registry image has already been pulled will it be run, exposing port 5000.
• The Docker Registry image will be pulled from Docker Hub using port 5000.

You would prepare an image called hello-world for uploading to a local Docker Registry using which of the following commands?

• docker tag hello-world localhost:5000/hello-world:latest (Ans)
• docker tag hello-world localhost/hello-world:latest
• docker -tag 127.0.0.1/hello-world:latest
• docker -t hello-world localhost:5000/hello-world:latest

To add encryption using a self-signed certificate to your Docker Registry infrastructure, to which directory must the certificate be copied (assuming your domain is
domain.com)?

• /etc/docker/certs.d/domain.com:5000/ (Ans)
• /etc/docker/cert.d/domain.com:5000/
• /var/lib/docker/certs.d/domain.com:5000/
• /etc/docker/certs.d/domain.com/

Which of these is the correct command to display a list images currently stored in a Docker Registry using a self-signed certificate?

• curl –insecure http://192.168.1.16:5000/v2/_catalog
• curl -i https://192.168.1.16:5000/v2/_catalog
• curl -i https://192.168.1.16:5000/v2/_data
• curl –insecure https://192.168.1.16:5000/v2/_catalog (Ans)

How do you temporarily enable Docker Content Trust on your local machine to take advantage of digitally signed images?

• export DOCKER_CONTENT_TRUST=1 (Ans)
• export $DOCKER_CONTENT_TRUST=0
• echo DOCKER_CONTENT_TRUST=1 >> /etc/profile
• echo $DOCKER_CONTENT_TRUST=1

Rajesh Kumar

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