Why do online exams block virtual machines?
Every major online exam delivery system prohibits virtual machines, and every one of them prohibits remote-access software during the exam. Pearson VUE's OnVUE lists virtual machines or beta operating systems under prohibited technology. ProctorU states that you will not be permitted to take your exam from within a virtual machine, and that you will be asked to reconnect using your host operating system. ETS requires all screen-sharing and remote-access software to be disabled before the test. The Duolingo English Test's published policies say, simply, do not use a virtual machine. PSI's check-in process tests your system to ensure no prohibited programs are running.
The reason is the same across all five systems, and it is structural rather than punitive: an online exam result is only trustworthy if the vendor can verify and monitor the environment the exam runs in. A virtual machine inserts a simulated computer between the vendor and your real machine, and remote-access software allows a computer to be viewed or controlled from somewhere else. Either one breaks the verified-environment model the exam's integrity rests on.
This page covers the published picture in general terms: what virtual machines and remote-access software are, the exact rule each vendor publishes, where in the exam-day journey the environment checks happen, what happens if your setup fails one, and the official preparation steps. Every claim comes from the official documentation of five delivery systems: Pearson VUE OnVUE, ETS at home, ProctorU, PSI online proctoring, and the Duolingo English Test.
The two prohibited categories, defined plainly
A virtual machine is a computer simulated in software. It runs as a program on your real computer - the host - and presents a second, complete computer inside it: its own operating system, its own desktop, its own applications. From the inside, an exam running in a virtual machine looks like it is running on an ordinary machine. From the outside, everything about the host - its files, its other programs, its other windows - sits one layer removed from whatever is running inside the virtual machine.
Remote-access software does the opposite job: instead of simulating a computer, it exports a real one. Screen-sharing tools let someone in another place see what is on your screen, and remote-control tools let them operate your keyboard and mouse as if they were sitting at your desk. ETS's published rule names the category directly: any screen-sharing or remote-access software must be disabled prior to the test.
The two categories appear together in vendor rules because they compromise the same requirement from opposite directions. A virtual machine puts a simulated environment between the vendor and the candidate's real machine; remote-access software opens the real machine to someone who is not in the room. An online exam's integrity depends on the machine in front of the candidate being the whole story - the one environment the vendor checked, and the one the candidate alone is using.
The rule each vendor publishes
Pearson VUE's OnVUE publishes the most compact version. Its program pages list minimum requirements - Windows 10 or macOS 14 or higher, one display screen only with multi-monitor setups not permitted, a stable internet connection of at least 6 Mbps download and 2 Mbps upload, and the ability to close all applications except OnVUE - followed by a prohibited technology list that begins with virtual machines or beta operating systems and also covers phones, tablets, smart or connected devices, secondary or touchscreen displays, and VPNs, corporate networks, or public and shared networks.
ProctorU's official equipment requirements state the rule as a direct prohibition: you will not be permitted to take your exam from within a virtual machine. The same article adds the recovery path and the remote-access rule: you will be asked to reconnect using your host operating system to take your exam, and you will not be permitted to test with remote-control software running on your computer. It also limits candidates to a single monitor when testing, with all others disconnected.
ETS writes the rule as a preparation instruction on its at-home test-day pages. Candidates must disable any screen-sharing or remote-access software prior to the test, and must close all browsers and applications not needed for the test. Compliance is verified before the exam begins: candidates run the Equipment Check from the ETS Secure Browser, and every issue it flags must be resolved and the check passed before checking in.
The Duolingo English Test's published Test Policies, Rules, and Requirements compress it into three instructions: do not use a virtual machine; close all programs other than the desktop app, including browsers and communication, streaming, and remote-desktop software; use only one keyboard, mouse, and phone. The same policies require predictive-text, proofreading, typing-suggestion, and reference software to be disabled. PSI, meanwhile, does not publish a product list - its exam-experience guide describes a check-in step that tests your microphone and webcam to ensure no prohibited programs are running.
Why the rules exist: one verified environment
Online proctoring rests on a single arrangement: the vendor watches one verified environment for the length of the exam. PSI describes its online proctoring team monitoring the session through screenshare, webcam, and microphone, and describes its check-in scans as ensuring that the testing conditions are fair. OnVUE's check-in includes a 360-degree room scan to confirm your environment is ready. None of that monitoring means anything if the environment being watched is not the environment the candidate is actually using.
That is the structural problem with a virtual machine. The vendor's checks and the proctor's view land on the simulated machine, while the candidate's real machine - the host - sits one layer outside that view. The exam's monitoring record would describe a computer that is not the computer in front of the candidate.
Remote-access software breaks the arrangement from the other side. The monitored environment is real, but it is no longer solely the candidate's: someone elsewhere can see the screen, and with remote-control software can operate the machine. The vendors' published rules therefore treat the two categories as one requirement - the exam must run on a real machine, under the candidate's direct control, with nothing between the vendor's checks and the candidate's actual environment.
Where the environment checks happen
The first checkpoint happens before exam day, and every vendor publishes one. OnVUE requires candidates to run and pass its System Test on the same device and network they will use on exam day. ETS has candidates run the Equipment Check from the ETS Secure Browser - at the time of day they plan to test - and requires every flagged issue to be resolved and the check passed before check-in. PSI publishes a publicly available System Compatibility Check so candidates can confirm their computer meets the necessary specifications, and ProctorU's equipment documentation sets the minimums its sessions expect: Windows 10 or later or Mac OS 11.0 or later, a single monitor, and no virtual machine.
The second checkpoint is check-in itself. OnVUE describes required technology checks to assess your equipment as part of check-in, alongside identity photos and the room scan. PSI's check-in tests the microphone and webcam specifically to ensure no prohibited programs are running. The exam countdown has not started at this point - PSI notes it will not start until you have passed the security checks and accessed your exam - so a problem found here is an eligibility problem, not lost exam time.
The third layer is the session itself. Once the exam is running, the delivery software is the only application the rules allow on the machine: OnVUE requires the ability to close all applications except OnVUE, ETS requires all unneeded browsers and applications closed, and the Duolingo English Test requires every program other than its desktop app to be closed. The session is monitored - PSI's team watches through screenshare, webcam, and microphone - so the environment that passed the checks is the environment that stays under review.
If your setup fails a check
The published outcomes depend on where the problem surfaces, and ProctorU publishes the gentlest case. Its equipment requirements state that if you connect from within a virtual machine, you will be asked to reconnect using your host operating system to take your exam. The exam is preserved; the environment is corrected before anything is at stake.
ETS's published case is the pre-exam gate: if you fail the Equipment Check, you must resolve all issues shown in red and pass the equipment check prior to checking in for your test. ETS maintains an Equipment Check Support page for troubleshooting, and it tells candidates to run the check at the time of day they plan to test and again shortly before the session - the design assumption is that problems are found and fixed before they cost anything.
OnVUE publishes the hard edge. Its program pages warn before booking that all test takers must ensure they can meet the minimum requirements, and that failure to do so on exam day can result in immediate exam cancellation and forfeiture of your exam fee. The same warning repeats at check-in: if any requirement is not met, you cannot test, and your fee will be forfeited. Each program sets its own policy, but the direction across all five vendors is the same - the environment rules are eligibility rules, and the cheap place to discover a problem is the pre-exam check, not exam day.
Work computers and managed networks
Read together, the rules converge on a practical conclusion no vendor states in one sentence: the safest exam machine is a personal computer on a home network. Work machines and managed networks sit inside exactly the categories the rules prohibit. OnVUE's prohibited technology list covers VPNs, corporate networks, and public or shared networks outright.
ETS adds the network-side warning: if you are testing on a work, public, or university network, make sure the network allows the required test-related screen sharing with the proctor - some networks block it, and that can prevent you from testing. A corporate laptop compounds the problem at the software layer, because employer-managed machines commonly run the remote-management and remote-access software categories that must be disabled or absent.
None of this makes a work computer impossible - it makes it a risk to clear in advance, using the vendors' own instruments. Run OnVUE's System Test, the ETS Equipment Check, or PSI's System Compatibility Check on the actual machine, on the actual network, ahead of exam day. If the setup cannot pass the published checks, the published minimums have not been met - and on OnVUE, that is a booking decision to make before the fee is at stake.
The published preparation checklist
Read across all five vendors, the official guidance converges on one checklist. Use a real computer - not a virtual machine, not a beta operating system - running a supported operating system: Windows 10 or later, macOS 14 or later for OnVUE, Mac OS 11.0 or later for ProctorU, or a recent compatible ChromeOS in the workflows where the vendor allows it.
Strip the machine down to the exam. Close every application except the delivery software, disable any screen-sharing or remote-access software, disable predictive-text and reference tools where the vendor calls them out, and keep one display, one keyboard, and one mouse. Then strip the network down the same way: a private home connection, with no VPN and no corporate or public network in the path.
Finally, prove it before it counts. Run the vendor's own check - the OnVUE System Test, the ETS Equipment Check, PSI's System Compatibility Check - on the same device and the same network you will use for the real session, fix everything it flags, and run it again shortly before the exam. Every vendor's documentation points the same direction: the environment check exists so that exam day holds no surprises.
If the Sitting Itself Is the Problem
A virtual-machine or remote-access rule is a solvable problem: the vendors publish the rules, the checks, and the consequences, and nothing in this page comes from anywhere but their own documentation. The harder problem is the exam on the other side of the checks - the proctored test itself, on a deadline, with a result that decides your next step.
That is the problem Exam Assist works on. If you have a proctored exam coming up and the sitting itself is the risk, send the exam, your window, and your deadline. You get an honest feasibility answer, and the service fee is due only after your result posts.
For more of this series in the same general-terms format, see our guides to what to expect at remote exam check-in, what happens if your internet drops during an online exam, and the vendor overviews for OnVUE, the ETS Secure Browser, and ProctorU.