Operating systems: install, update and recover interview questions

That this is the supported behaviour, not a fault. Microsoft's Windows 11 specifications say Home and Pro for personal use require internet connectivity and a Microsoft account during initial setup, and recent preview builds removed the old ways of skipping it, so what works depends on the exact build. I would not leave an unsupported workaround on the machine. For a personal device I would help the user sign in with, or create, a Microsoft account, and explain that they can still add a local account afterwards. For a work device the question does not arise: it joins the organisation's directory during setup through Autopilot or a provisioning package, and the user signs in with a work identity. The goal is that the right account owns the PC, so I match the account to who owns the machine.

The chip decides the keys. A Mac with Apple silicon is shut down, then its power button is held until the screen reads "Loading startup options"; release it, choose Options and click Continue. An Intel Mac is turned on with the power button and then Command-R is held until a logo or a spinning globe appears. Recovery next asks which volume to recover, usually Macintosh HD, and for an account on that Mac whose login password you know. That is a macOS login password, never an Apple Account password, and when nobody has it the job turns into a reset through "Forgot all passwords?", which asks for a recovery key or the Apple Account the Mac was set up with.

Ask what has to survive. If the Mac stays with that user and its software is broken, the job is Reinstall macOS from Recovery: it writes a new copy of the system and leaves accounts, documents, apps and settings alone, so nothing is restored afterwards. If the Mac is leaving them, the job is Erase All Content and Settings in System Settings, which removes data, apps and settings, signs the Mac out of Apple services and stops at the setup assistant with the installed macOS still there. The first is reversible in effect; the second is not, so files are backed up or transferred before it begins. One question, "who uses this Mac next?", separates them.

No. Ubuntu Desktop installs and runs with Secure Boot on, because its boot loader is signed with a key the firmware trusts, and the drivers Canonical's own tools install by default are the pre-built, signed ones that work with the setting on. Switching it off is a change to the machine's firmware that removes a protection against unsigned boot code, and it tends to stay off for the rest of the PC's life. The time the question really comes up is when someone installs a graphics driver built outside Ubuntu's own packages, which can leave the system unable to boot with the setting on — and the fix is to use the signed driver, not to weaken the firmware.

Only after reading the whole row. The list gives each model a status and the year its certification ends, and both matter. A row marked "major issues expected" means boot problems are known; a decertified row, or one whose year is nearly here, means Google stops testing that model and will not support it, so every fault afterwards lands on your desk. Check also that the row is for the exact model name and number, because Google's documentation warns that variants of a model may behave differently, and that the machine clears the minimums of 4 GB of memory and 16 GB of storage on an x86-64 processor newer than 2012.

The second-Tuesday release, marked B in Microsoft's release table, is the month's security update. It is cumulative, so it contains every earlier fix, and it is the one a support desk rolls out to all machines. The optional preview, marked D, appears later in the same month and carries non-security fixes for the month ahead. It is optional by design: it is meant for a test machine so you can catch a problem before the next required update, not for the whole fleet. Both may fix the same things, but only the security release is required and cumulative, so the preview is for trying, and the security release is for installing everywhere.

Not necessarily. Windows opens its recovery environment automatically after two consecutive failed attempts to start, after two unexpected shutdowns shortly after starting, or after a Secure Boot error. The trigger is a status flag that was not cleared, not a diagnosis, so a power cut during a healthy start can set it. I would ask what happened just before, let Automatic Repair finish, and restart once. If the menu comes back, the tools in it are the next step, starting with the least disruptive. I would also check that a BitLocker recovery key can be retrieved before trying anything, because Microsoft says most recovery options in WinRE ask for it.

From the tool that changes least. Point-in-time restore comes first on Windows 11 24H2 or later, when a restore point from the last 3 days exists. Then Uninstall updates, if an update started the trouble, then Reset this PC, and last reinstalling from recovery or installation media. System Restore covers older restore points, and safe mode is a way to look at the problem rather than a repair. Each step down loses more of the user's setup, so I stop at the first one that works and write down which one it was. The user's recent files decide the choice between the first two, because a restore returns files to the restore point.

The sensor's driver runs in the kernel and loads from an early phase of start-up. The faulty content was stored on disk and read at every start, so each restart reached the same rule, the same read past the end of an array and the same blue screen. Restarting repeats the cause instead of removing it. The repair therefore had to happen from outside the installed Windows, by starting from recovery media or into safe mode, and removing the faulty channel files before the driver read them again. On an encrypted PC that meant the volume had to be opened first, which is why the recovery key became part of the story.

The WinPE route, which Microsoft recommends, when recovery keys can be supplied quickly: it needs no local administrator account and repairs the PC directly, but may need the BitLocker recovery key typed for each encrypted device. The safe mode route may avoid the key on PCs with TPM-only protectors, but it needs a local administrator account on every PC, and a PC with a TPM and a PIN still needs the PIN or the key. So three facts decide it: whether keys are retrievable in bulk, whether a local administrator is available, and whether the PCs can boot from USB. Either way I would try the route on a few PCs first, as Microsoft advises.

The key that opens the system volume is sealed to the TPM together with measurements of the early start-up parts, and a firmware update changes one of them. The TPM sees that the measurements no longer match and keeps the key, so Windows shows the recovery screen. Nothing is broken: the lock did what it is meant to do. For a planned update the prompt is avoided with a step before it: suspend BitLocker, apply the update, resume, and the key is resealed to the new values without anyone typing a key. If the update was not planned, I would ask what changed before giving anyone a key, because the cause may be tampering.

I write the device name, the key ID shown on the recovery screen, the cause of the recovery as the user described it, how the caller was verified, and the time. The key ID and the device name are enough to find the same key again, and they are safe to keep because they open nothing. The 48 digits never go in the ticket, a chat message or an email, because every system they pass through keeps them, and a ticket is read by far more people than the owner of the laptop. After the call I rotate the key where the tooling supports it, because a key that has been read aloud is no longer private.

It always removes apps and settings, because it reinstalls Windows. With Keep my files it keeps documents and photos; with Remove everything it removes personal files too, and Clean data goes further and cleans the drive for a PC that is being donated or sold. Microsoft adds that this erasure is aimed at consumers and does not meet government or industry data erasure standards. Before I start I back up the files, check that the BitLocker recovery key is available if the PC is encrypted, put the PC on power, and tell the user that the screen may stay black for a long time and that restarting it by hand can make the reset fail.

When system files are damaged and the PC runs Windows 11 version 22H2 or later with updates that are not managed by an organisation. The reinstall from Windows Update puts the same version back, repairs system files and components, and keeps apps, files and settings, so the user loses nothing. I try it after DISM and sfc have not cleared the damage and before a reset. On a managed PC the option may be missing, and then the question goes to the endpoint team, who may have a repair source, an Autopilot Reset or a reimage set up for exactly this.