KVM & libvirt interview questions

99 real KVM & libvirt questions from the Virtualization bank, as asked in Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd — free to start.

1. What is virtio?

Junior
  1. A.A paravirtualized device standard for KVM/QEMU giving guests efficient virtio-net, virtio-blk and virtio-scsi drivers instead of slow emulated hardware
  2. B.Allocating guest memory from host huge pages to cut TLB misses, commonly required for DPDK and high-performance KVM workloads
  3. C.Copy-on-write QEMU disk format supporting snapshots, thin provisioning, compression, and backing files.
  4. D.A userspace dataplane interface that connects virtio devices to an external process such as a DPDK/OVS poll-mode driver for line-rate networking
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2. Which term means: "A paravirtualized device standard for KVM/QEMU giving guests efficient virtio-net, virtio-blk and virtio-scsi drivers instead of slow emulated hardware"?

Junior
  1. A.virtio
  2. B.cloud-init
  3. C.Linux bridge networking
  4. D.vhost-net
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3. Which statement is correct?

Junior
  1. A.virtio — Allocating guest memory from host huge pages to cut TLB misses, commonly required for DPDK and high-performance KVM workloads
  2. B.virtio — A guest-side tool that configures a freshly booted cloud image (hostname, SSH keys, network, packages) from metadata supplied by the platform
  3. C.virtio — A shared-filesystem device that lets a guest directly access a directory on the host with near-native performance, used heavily by KubeVirt and Kata
  4. D.virtio — A paravirtualized device standard for KVM/QEMU giving guests efficient virtio-net, virtio-blk and virtio-scsi drivers instead of slow emulated hardware
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4. What is virtio-fs?

Mid
  1. A.A Linux framework that carves a physical device, typically a GPU, into virtual instances passed through to VMs, the basis of NVIDIA vGPU on KVM
  2. B.Allocating guest memory from host huge pages to cut TLB misses, commonly required for DPDK and high-performance KVM workloads
  3. C.Assigns a host PCI device (GPU, NIC) directly to a guest via the vfio-pci driver and IOMMU groups.
  4. D.A shared-filesystem device that lets a guest directly access a directory on the host with near-native performance, used heavily by KubeVirt and Kata
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5. Which term means: "A shared-filesystem device that lets a guest directly access a directory on the host with near-native performance, used heavily by KubeVirt and Kata"?

Mid
  1. A.Linux bridge networking
  2. B.huge pages backing
  3. C.virtio-fs
  4. D.libvirt domain XML
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6. Which statement is correct?

Mid
  1. A.virtio-fs — A shared-filesystem device that lets a guest directly access a directory on the host with near-native performance, used heavily by KubeVirt and Kata
  2. B.virtio-fs — A guest-side tool that configures a freshly booted cloud image (hostname, SSH keys, network, packages) from metadata supplied by the platform
  3. C.virtio-fs — The declarative XML definition of a VM (CPU, memory, disks, NICs) that libvirt uses to create and manage the guest across hypervisors
  4. D.virtio-fs — Multilayer virtual switch giving KVM guests VLANs, tunneling, and OpenFlow-controlled networking.
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7. What is vhost-net?

Senior
  1. A.AMD Secure Encrypted Virtualization-Secure Nested Paging: encrypts and integrity-protects a VM's memory from the hypervisor, enabling confidential VMs on KVM
  2. B.A shared-filesystem device that lets a guest directly access a directory on the host with near-native performance, used heavily by KubeVirt and Kata
  3. C.A kernel module that moves virtio-net packet processing into the host kernel, bypassing the QEMU userspace data path for higher network throughput
  4. D.Copy-on-write QEMU disk format supporting snapshots, thin provisioning, compression, and backing files.
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8. Which term means: "A kernel module that moves virtio-net packet processing into the host kernel, bypassing the QEMU userspace data path for higher network throughput"?

Senior
  1. A.vhost-net
  2. B.mediated device (mdev)
  3. C.huge pages backing
  4. D.Hugepages backing
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9. Which statement is correct?

Senior
  1. A.vhost-net — Assigns a host PCI device (GPU, NIC) directly to a guest via the vfio-pci driver and IOMMU groups.
  2. B.vhost-net — Paravirtualized device model (net, blk, scsi) giving near-native I/O performance to KVM guests.
  3. C.vhost-net — A kernel module that moves virtio-net packet processing into the host kernel, bypassing the QEMU userspace data path for higher network throughput
  4. D.vhost-net — A Linux framework that carves a physical device, typically a GPU, into virtual instances passed through to VMs, the basis of NVIDIA vGPU on KVM
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10. What is vhost-user?

Senior
  1. A.A userspace dataplane interface that connects virtio devices to an external process such as a DPDK/OVS poll-mode driver for line-rate networking
  2. B.libvirt XML element that pins guest memory to specific host NUMA nodes for bandwidth-sensitive workloads.
  3. C.virtio-scsi supports more disks, TRIM/discard, and SCSI passthrough; virtio-blk is simpler and slightly faster.
  4. D.Multilayer virtual switch giving KVM guests VLANs, tunneling, and OpenFlow-controlled networking.
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11. Which term means: "A userspace dataplane interface that connects virtio devices to an external process such as a DPDK/OVS poll-mode driver for line-rate networking"?

Senior
  1. A.cloud-init
  2. B.Open vSwitch integration
  3. C.PCI passthrough (VFIO)
  4. D.vhost-user
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12. Which statement is correct?

Senior
  1. A.vhost-user — Copy-on-write QEMU disk format supporting snapshots, thin provisioning, compression, and backing files.
  2. B.vhost-user — A userspace dataplane interface that connects virtio devices to an external process such as a DPDK/OVS poll-mode driver for line-rate networking
  3. C.vhost-user — Paravirtualized device model (net, blk, scsi) giving near-native I/O performance to KVM guests.
  4. D.vhost-user — Assigns a host PCI device (GPU, NIC) directly to a guest via the vfio-pci driver and IOMMU groups.
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13. What is cloud-init?

Junior
  1. A.A shared-filesystem device that lets a guest directly access a directory on the host with near-native performance, used heavily by KubeVirt and Kata
  2. B.Backs guest RAM with 2MB or 1GB pages to cut TLB misses and reduce page-table overhead.
  3. C.A guest-side tool that configures a freshly booted cloud image (hostname, SSH keys, network, packages) from metadata supplied by the platform
  4. D.libvirt XML element that pins guest memory to specific host NUMA nodes for bandwidth-sensitive workloads.
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14. Which term means: "A guest-side tool that configures a freshly booted cloud image (hostname, SSH keys, network, packages) from metadata supplied by the platform"?

Junior
  1. A.cloud-init
  2. B.vhost-net
  3. C.virtio
  4. D.Open vSwitch integration
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15. Which statement is correct?

Junior
  1. A.cloud-init — A copy-on-write base image referenced by a thin overlay qcow2, so many VMs share one read-only base while writing private deltas
  2. B.cloud-init — A guest-side tool that configures a freshly booted cloud image (hostname, SSH keys, network, packages) from metadata supplied by the platform
  3. C.cloud-init — Software bridge (br0) connecting guest tap interfaces to a physical NIC for direct L2 access.
  4. D.cloud-init — virtio-scsi supports more disks, TRIM/discard, and SCSI passthrough; virtio-blk is simpler and slightly faster.
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16. What is mediated device (mdev)?

Senior
  1. A.Backs guest RAM with 2MB or 1GB pages to cut TLB misses and reduce page-table overhead.
  2. B.A kernel module that moves virtio-net packet processing into the host kernel, bypassing the QEMU userspace data path for higher network throughput
  3. C.Software bridge (br0) connecting guest tap interfaces to a physical NIC for direct L2 access.
  4. D.A Linux framework that carves a physical device, typically a GPU, into virtual instances passed through to VMs, the basis of NVIDIA vGPU on KVM
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17. Which term means: "A Linux framework that carves a physical device, typically a GPU, into virtual instances passed through to VMs, the basis of NVIDIA vGPU on KVM"?

Senior
  1. A.vhost-user
  2. B.PCI passthrough (VFIO)
  3. C.mediated device (mdev)
  4. D.NUMA tuning (numatune)
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18. Which statement is correct?

Senior
  1. A.mediated device (mdev) — Paravirtualized device model (net, blk, scsi) giving near-native I/O performance to KVM guests.
  2. B.mediated device (mdev) — Software bridge (br0) connecting guest tap interfaces to a physical NIC for direct L2 access.
  3. C.mediated device (mdev) — A Linux framework that carves a physical device, typically a GPU, into virtual instances passed through to VMs, the basis of NVIDIA vGPU on KVM
  4. D.mediated device (mdev) — A userspace dataplane interface that connects virtio devices to an external process such as a DPDK/OVS poll-mode driver for line-rate networking
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19. What is SEV-SNP?

Senior
  1. A.A guest-side tool that configures a freshly booted cloud image (hostname, SSH keys, network, packages) from metadata supplied by the platform
  2. B.Allocating guest memory from host huge pages to cut TLB misses, commonly required for DPDK and high-performance KVM workloads
  3. C.Paravirtualized device model (net, blk, scsi) giving near-native I/O performance to KVM guests.
  4. D.AMD Secure Encrypted Virtualization-Secure Nested Paging: encrypts and integrity-protects a VM's memory from the hypervisor, enabling confidential VMs on KVM
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20. Which term means: "AMD Secure Encrypted Virtualization-Secure Nested Paging: encrypts and integrity-protects a VM's memory from the hypervisor, enabling confidential VMs on KVM"?

Senior
  1. A.qcow2 backing file
  2. B.virtio drivers
  3. C.SEV-SNP
  4. D.virtio-scsi vs virtio-blk
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21. Which statement is correct?

Senior
  1. A.SEV-SNP — The declarative XML definition of a VM (CPU, memory, disks, NICs) that libvirt uses to create and manage the guest across hypervisors
  2. B.SEV-SNP — A shared-filesystem device that lets a guest directly access a directory on the host with near-native performance, used heavily by KubeVirt and Kata
  3. C.SEV-SNP — Multilayer virtual switch giving KVM guests VLANs, tunneling, and OpenFlow-controlled networking.
  4. D.SEV-SNP — AMD Secure Encrypted Virtualization-Secure Nested Paging: encrypts and integrity-protects a VM's memory from the hypervisor, enabling confidential VMs on KVM
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22. What is libvirt domain XML?

Junior
  1. A.A guest-side tool that configures a freshly booted cloud image (hostname, SSH keys, network, packages) from metadata supplied by the platform
  2. B.A copy-on-write base image referenced by a thin overlay qcow2, so many VMs share one read-only base while writing private deltas
  3. C.The declarative XML definition of a VM (CPU, memory, disks, NICs) that libvirt uses to create and manage the guest across hypervisors
  4. D.Paravirtualized device model (net, blk, scsi) giving near-native I/O performance to KVM guests.
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23. Which term means: "The declarative XML definition of a VM (CPU, memory, disks, NICs) that libvirt uses to create and manage the guest across hypervisors"?

Junior
  1. A.cloud-init
  2. B.qcow2 format
  3. C.Linux bridge networking
  4. D.libvirt domain XML
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24. Which statement is correct?

Junior
  1. A.libvirt domain XML — A kernel module that moves virtio-net packet processing into the host kernel, bypassing the QEMU userspace data path for higher network throughput
  2. B.libvirt domain XML — The declarative XML definition of a VM (CPU, memory, disks, NICs) that libvirt uses to create and manage the guest across hypervisors
  3. C.libvirt domain XML — Multilayer virtual switch giving KVM guests VLANs, tunneling, and OpenFlow-controlled networking.
  4. D.libvirt domain XML — Paravirtualized device model (net, blk, scsi) giving near-native I/O performance to KVM guests.
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25. What is qcow2 backing file?

Senior
  1. A.A Linux framework that carves a physical device, typically a GPU, into virtual instances passed through to VMs, the basis of NVIDIA vGPU on KVM
  2. B.libvirt XML element that pins guest memory to specific host NUMA nodes for bandwidth-sensitive workloads.
  3. C.Software bridge (br0) connecting guest tap interfaces to a physical NIC for direct L2 access.
  4. D.A copy-on-write base image referenced by a thin overlay qcow2, so many VMs share one read-only base while writing private deltas
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26. Which term means: "A copy-on-write base image referenced by a thin overlay qcow2, so many VMs share one read-only base while writing private deltas"?

Senior
  1. A.virtio drivers
  2. B.Hugepages backing
  3. C.qcow2 backing file
  4. D.Open vSwitch integration
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27. Which statement is correct?

Senior
  1. A.qcow2 backing file — A userspace dataplane interface that connects virtio devices to an external process such as a DPDK/OVS poll-mode driver for line-rate networking
  2. B.qcow2 backing file — The declarative XML definition of a VM (CPU, memory, disks, NICs) that libvirt uses to create and manage the guest across hypervisors
  3. C.qcow2 backing file — A guest-side tool that configures a freshly booted cloud image (hostname, SSH keys, network, packages) from metadata supplied by the platform
  4. D.qcow2 backing file — A copy-on-write base image referenced by a thin overlay qcow2, so many VMs share one read-only base while writing private deltas
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28. What is huge pages backing?

Mid
  1. A.A paravirtualized device standard for KVM/QEMU giving guests efficient virtio-net, virtio-blk and virtio-scsi drivers instead of slow emulated hardware
  2. B.The declarative XML definition of a VM (CPU, memory, disks, NICs) that libvirt uses to create and manage the guest across hypervisors
  3. C.virtio-scsi supports more disks, TRIM/discard, and SCSI passthrough; virtio-blk is simpler and slightly faster.
  4. D.Allocating guest memory from host huge pages to cut TLB misses, commonly required for DPDK and high-performance KVM workloads
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29. Which term means: "Allocating guest memory from host huge pages to cut TLB misses, commonly required for DPDK and high-performance KVM workloads"?

Mid
  1. A.cloud-init
  2. B.qcow2 format
  3. C.huge pages backing
  4. D.Hugepages backing
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30. Which statement is correct?

Mid
  1. A.huge pages backing — A userspace dataplane interface that connects virtio devices to an external process such as a DPDK/OVS poll-mode driver for line-rate networking
  2. B.huge pages backing — Allocating guest memory from host huge pages to cut TLB misses, commonly required for DPDK and high-performance KVM workloads
  3. C.huge pages backing — Software bridge (br0) connecting guest tap interfaces to a physical NIC for direct L2 access.
  4. D.huge pages backing — A kernel module that moves virtio-net packet processing into the host kernel, bypassing the QEMU userspace data path for higher network throughput
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