Mixed Deck — All OpenStack Topics Flashcards

Which OpenStack service is used for DNS-as-a-Service?

Answer: Designate

Designate is the OpenStack DNS service that manages DNS zones and records, integrating with backends like BIND and PowerDNS.

What is the 'visibility' property of a Glance image?

Answer: Controls who can see and use the image (public, private, shared, community)

Glance image visibility controls access: 'public' images are available to all tenants, 'private' only to the owner.

What does ML2 stand for in the context of Neutron's plugin architecture?

Answer: Modular Layer 2

ML2 stands for Modular Layer 2, a framework that allows OpenStack Neutron to use multiple Layer 2 technologies simultaneously.

What is a Nova 'availability zone' used for?

Answer: Logically partitioning compute resources to allow tenants to select specific infrastructure zones

Nova availability zones allow users to specify which logical partition of compute resources to deploy instances into.

What is QoS (Quality of Service) used for in Neutron?

Answer: Controlling network bandwidth and traffic policies on ports and networks

Neutron QoS policies allow administrators to set bandwidth limits, minimum bandwidth guarantees, and DSCP marks on network ports.

What is VXLAN in the context of OpenStack Neutron overlay networks?

Answer: A tunneling protocol that encapsulates L2 frames in UDP to extend networks over L3

VXLAN (Virtual Extensible LAN) encapsulates Layer 2 Ethernet frames within UDP packets, enabling large-scale overlay networks.

Which OpenStack CLI command lists all Neutron networks visible to your project?

Answer: openstack network list

The 'openstack network list' command displays all networks accessible to the current project.

What is 'image caching' in the context of Nova and Glance?

Answer: Storing copies of Glance images locally on compute nodes to speed up instance boot

Nova image caching stores Glance images locally on compute nodes so subsequent boots of the same image are faster.

What Glance property 'min_disk' specifies?

Answer: The minimum root disk size (in GB) required to boot an instance from the image

The 'min_disk' property specifies the minimum root disk size in GB that a Nova flavor must have to boot from this image.

What is the purpose of Nova's 'resize' operation?

Answer: Changing a VM's flavor to one with different vCPU/RAM/disk specifications

Nova resize allows changing a VM's flavor (compute resources like vCPUs and RAM) by migrating it to a host that can accommodate the new flavor.

Which Keystone token format is the current default and does not require backend validation for each request?

Answer: Fernet token

Fernet tokens are the current default in OpenStack Keystone; they are lightweight, encrypted, and stateless (no persistence required).

What is the purpose of a Keystone 'endpoint' in OpenStack?

Answer: A URL registered in the service catalog for a specific service and region

Keystone endpoints are URLs stored in the service catalog that clients use to reach a specific OpenStack service in a given region.

In OpenStack Heat, what is a 'stack'?

Answer: A collection of OpenStack resources created and managed as a single unit

A Heat stack is a set of OpenStack resources (VMs, networks, volumes, etc.) that are created, updated, and deleted together as one deployable unit.

In OpenStack, what does 'ephemeral storage' refer to?

Answer: Temporary disk storage tied to a VM instance's lifecycle that is lost when the instance is deleted

Ephemeral storage is the temporary local disk attached to a VM instance that is destroyed when the instance is terminated.

Which three parts of OpenStack are required for Nova to work?

Answer: Keystone, Glance and Neutron

Explanation: Nova gives enterprises a way to provision resources, such as VMs, bare-metal servers and containers. To perform its basic functions, Nova requires the Keystone, Glance and Neutron components.

Which OpenStack service stores and retrieves virtual machine disk images?

Answer: Glance

Glance is the OpenStack Image Service that stores, discovers, and retrieves VM disk images used to boot instances.

What is the role of the Neutron metadata agent?

Answer: It relays instance metadata requests from VMs to the Nova metadata API

The neutron-metadata-agent proxies requests from VMs to the Nova metadata API, enabling instances to retrieve their configuration data.

Which Neutron feature provides load balancing capabilities as a service?

Answer: LBaaS (Octavia)

LBaaS (Load Balancer as a Service), now implemented via Octavia, provides load balancing functionality within OpenStack.

What is a Keystone 'domain' used for in multi-tenant deployments?

Answer: A high-level administrative boundary for grouping projects and users

Keystone domains provide a high-level administrative boundary to isolate users and projects, enabling multi-organization deployments.

Which OpenStack service provides auto-scaling and orchestration of application stacks?

Answer: Heat

Heat provides stack orchestration and supports auto-scaling policies via integration with Ceilometer/Aodh to grow or shrink resource groups.