A KVM guest is used as a developer's daily desktop. The developer must plug a USB debugger into their own laptop and have the guest see it, and must get working audio. Which remote display protocol is designed for that class of virtual machine console, and what distinguishes it from plain VNC here?
LPIC-1 Exam 102-500, objective 106. User interfaces and desktops medium
Machine-checked — no person has signed for it. This question was read against the source cited below by an automated pass, which found no contradiction. That is a weaker claim than it sounds: the same kind of process wrote the question, so it can confirm its own mistake.
Treat it as a good draft rather than as settled fact, and read the source below before you rely on it. It is not used in mock exams here — only questions a person has signed for are.
How these questions are written — where each question comes from, what the verification ledger records, and what happens when one is found wrong.
The options
Correct Spice, because it was designed for virtual machine consoles and adds USB redirection from client to guest, audio channels and multiple monitors.
Correct. Spice is exported by the hypervisor rather than by software inside the guest, and its extra channels carry sound, clipboard and redirected USB devices alongside the display.
Not correct VNC, because the RFB protocol carries a dedicated USB channel that Spice lacks.
Wrong, and the claim is inverted. RFB transmits framebuffer updates and input events; it has no USB or audio channel of its own, which is precisely the gap Spice was written to fill.
Not correct XDMCP, because it negotiates device access when the X server attaches to the display manager.
Wrong. XDMCP negotiates only the offer of a login session to a remote X server. It transfers no devices and no audio.
Not correct SSH X11 forwarding, because forwarded clients inherit the local machine's devices directly.
Wrong. Forwarded X clients draw on your local X server, but they run on the remote host and see that host's devices. Nothing about the forwarding attaches your USB hardware to the remote machine.
Why
The four protocols in the objective divide by what they were written for: X11 forwarding moves individual applications, VNC mirrors an existing framebuffer across any operating system, RDP is Windows' native session protocol, and Spice is a virtualisation console protocol with side channels for audio, clipboard and USB redirection. Spice and VNC are both offered by QEMU/KVM for the same guest, so the choice between them is about those side channels rather than about the picture.
Where this comes from
- Cited
- LPI exam objective 106.2
Practise this
Reading one question is not practice. The trainer will draw a short set from objective 106 and space the ones you get wrong.
More questions on this objective
- In the X Window System architecture, which statement correctly describes the roles of the X server and an X client? machine-checked
- From your desktop workstation you run `ssh -X admin@fileserver` and then start `xterm` in that session. The xterm window appears on your workstation's screen. Which machine is running the X server in this arrangement, and which is running the X client? machine-checked
- In a bash shell, type the complete command that sets and exports the environment variable X clients read to find their display, so that they connect to screen 0 of display 0 on the local machine. machine-checked
- Type the command, with no arguments and no options, that prints whether host-based access control is currently enabled on your X server together with the list of hosts and users allowed to connect. machine-checked
- An X11-forwarded ssh session authorises the remote client to talk to your local X server without you ever running an xhost command. Which mechanism provides that authorisation? machine-checked
- A display manager is the program that presents the graphical login screen and starts the user's session after authentication. Which three of the following are display managers? (Choose three.) machine-checked