305-300 Practice Test 16 — 15 Questions

Question 1

You are managing a Xen host and need to live-migrate a domain between two physical servers. The migration fails with a domain lock error. Which command is the standard way to initiate a live migration while ensuring the target host is prepared to receive the domain?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

xl migrate . The 'xl migrate' command is the standard interface for Xen live migration, requiring the target host to be accessible and the source domain to be running.

Answer

xl save && xl restore

Answer

xen-migrate --live

Answer

virsh migrate --live

Question 2

Which THREE of the following are valid storage driver options for Docker on Linux?

Accepted Answer

overlay2. Docker supports multiple storage drivers including overlay2, btrfs, and zfs, depending on the underlying filesystem.

Answer

ext4-driver

Answer

vfs

Question 3

Which command-line tool is primarily used to inspect the metadata and configuration of a running Docker container?

Accepted Answer

docker inspect. docker inspect provides detailed information on containers and images in JSON format.

Answer

docker ps

Answer

docker stats

Answer

docker info

Answer

docker describe

Question 4

You want to optimize disk I/O performance for a KVM guest. Which bus type should you configure in the libvirt domain XML for the virtual disk?

Accepted Answer

virtio. virtio is the paravirtualized driver set that provides the highest performance for KVM guests.

Answer

scsi

Answer

usb

Answer

ide

Question 5

Which TWO of the following are valid network modes for a libvirt virtual network?

Accepted Answer

bridge. NAT and bridge are standard libvirt network modes.

Answer

switch

Answer

peer

Answer

router

Question 6

Which THREE of the following steps are involved in performing a manual disk migration of a VM?

Accepted Answer

Editing the domain XML on the target host. Copying the image, editing the XML, and redefining the domain are the correct workflow steps.

Answer

Reformatting the disk image

Answer

Updating the host kernel

Question 7

When using systemd-nspawn, you want to limit the memory usage of a container to 512MB. Which flag should be passed to the systemd-nspawn command?

Accepted Answer

--memory-limit=512M. systemd-nspawn uses the --memory-limit flag to restrict the memory consumption of the spawned container.

Answer

--max-mem=512M

Answer

--cgroup-memory=512M

Answer

--limit-mem=512M

Question 8

Which instruction in a Dockerfile is best suited for installing packages to minimize image size?

Accepted Answer

RUN apt-get update && apt-get install -y package && rm -rf /var/lib/apt/lists/*. Combining the update and install commands with 'rm -rf /var/lib/apt/lists/*' in a single RUN command prevents layer bloat.

Answer

COPY apt-cache /

Answer

CMD apt-get install package

Answer

RUN apt-get update && apt-get install -y package

Question 9

Which Docker network driver should you use if you want containers to have their own IP addresses on the physical network, as if they were physically connected to the network?

Accepted Answer

macvlan. The 'macvlan' driver allows containers to be assigned a MAC address and IP on the physical network.

Answer

bridge

Answer

overlay

Answer

ipvlan

Question 10

You are troubleshooting a libvirt network issue where the virtual machines cannot reach the external gateway. The virtual network uses a NAT configuration. Which file would you inspect to verify the iptables rules generated by libvirt for this network?

Accepted Answer

/etc/libvirt/qemu/networks/default.xml. Libvirt manages iptables rules dynamically, but the configuration is stored in the libvirt network XML files in /etc/libvirt/qemu/networks/ and the resulting rules appear in the NAT table.

Answer

/var/lib/libvirt/network/default.xml

Answer

/etc/sysconfig/network-scripts/ifcfg-virbr0

Answer

/etc/iptables/rules.v4

Question 11

What is the primary difference between a container image and a container instance?

Accepted Answer

The image is the template; the instance is the running process. A container image is a read-only template, whereas a container instance is a writable, running version of that image.

Answer

Images are stored in RAM, instances are on disk

Answer

Instances cannot be stopped

Answer

The instance is the template; the image is the running process

Answer

They are the same thing

Question 12

Which TWO of the following are true regarding container orchestration platforms?

Accepted Answer

They automate container deployment. Orchestration platforms manage scaling and automated recovery of containers.

Answer

They replace the container runtime

Answer

They only run on bare metal

Answer

They require a single container image

Question 13

You need to run a container that requires access to the host's network namespace directly to perform packet capture. Which Docker run flag should you use?

Accepted Answer

--network host. The --network host flag allows a container to share the host's networking namespace, providing full access to host network interfaces.

Answer

--cap-add NET_ADMIN

Answer

--privileged

Answer

--net bridge

Question 14

Which TWO of the following are valid container orchestration platforms?

Accepted Answer

Kubernetes. Kubernetes and HashiCorp Nomad are widely used orchestration platforms.

Answer

Nginx

Answer

Docker Desktop

Answer

GitLab

Question 15

What is the role of the 'Dockerfile' in the container build process?

Accepted Answer

To provide build instructions. It contains the instructions for building an image.

Answer

To define network topology

Answer

To list running containers

Answer

To store container data