Level 1 test

Why each option is right or wrong

• “Buy a bigger 2 TB disk so there's more room” (Incorrect): 700 GB is already free. Storage keeps files; it doesn't hold running programs, so more of it won't stop the freezing.
• “Reinstall the billing app every morning” (Incorrect): The app isn't broken. Reinstalling doesn't change how much memory everything together needs.
• “Fit a faster graphics card for the video call” (Incorrect): The video call uses some graphics power, but the freezing comes from memory filling up when everything runs together.
• “Add more RAM” is correct.

  RAM holds every program that's running right now. With the billing app, 30 tabs and a video call open together, 8 GB fills up, and the laptop starts swapping data to the much slower disk, which makes it freeze. The disk still has 700 GB free, so storage isn't the bottleneck.

  • Check first: Task Manager or Activity Monitor shows memory use near 100% when it freezes.
  • Free fix to try: close tabs that aren't needed before running billing.

📖 Revise: Module 1: How Computers Work

Why each option is right or wrong

• “The installed operating system and its settings” (Incorrect): The operating system lives on storage, so it survives a power loss, apart from rare corruption during a sudden cut.
• “Files already saved to the SSD” (Incorrect): Storage keeps saved files without power.
• “Photos synced to the cloud yesterday” (Incorrect): Those copies are on another company's servers, untouched by your power cut.
• “Edits that exist only in RAM” is correct.

  RAM only keeps data while it has power. Anything typed or changed but not yet saved exists only there, so when the UPS battery runs out, those edits are lost. Saved files sit on the SSD, which keeps them without power.

  • During a cut: save your work and shut down properly while the UPS lasts.
  • Autosave: helps, but only for apps that have it switched on.

📖 Revise: Module 1: How Computers Work

Why each option is right or wrong

• “Allow admin rights, but disconnect the internet first” (Incorrect): Offline admin access can still delete or break system files.
• “Allow admin rights just this once, then switch them off” (Incorrect): "Just once" is enough for a mistake or a bad command to damage the whole system.
• “Copy the whole disk into the project folder” (Incorrect): That exposes far more files to the tool, the opposite of least privilege.
• “Refuse, and allow access to the project folder only” is correct.

  The principle of least privilege says a tool should get only the access its task needs. Editing a project folder doesn't need administrator rights, which would let one mistake or bad command damage the whole computer. Grant folder access and say no to the rest.

  • Same rule: for apps, API keys and team accounts.
  • If it insists: find out exactly which file it can't reach and why.

📖 Revise: Module 2: Operating Systems

Why each option is right or wrong

• “How many browser tabs are open on the server” (Incorrect): Servers don't usually run browsers, and tabs use RAM, not disk.
• “The size of the images uploaded to the website” (Incorrect): Images take some space, but a sudden full disk is far more often logs or backups growing without limit.
• “The database's index settings and query plans” (Incorrect): Indexes affect speed and use some space, but logs and backups are the classic silent disk-fillers.
• “Log files or backups that grew without limit” is correct.

  When a disk fills up silently, the usual cause is something that keeps growing: log files that aren't trimmed, or backups that pile up. Find what grew with a disk-usage tool, free space safely, then set limits so it doesn't happen again.

  • Commands: df -h shows how full each disk is; du -sh * shows folder sizes.
  • Prevent: log rotation and a backup retention limit.

📖 Revise: Module 2: Operating Systems

Why each option is right or wrong

• “The server upgrades Node.js automatically on deploy” (Incorrect): Runtimes don't upgrade themselves on deploy; someone has to do it deliberately.
• “Only the page styling breaks on the live site” (Incorrect): Styling is CSS in the browser; this is a server-side runtime failure.
• “It works, because JavaScript is the same everywhere” (Incorrect): The language grows with each runtime version; old runtimes miss new features.
• “It fails on the server, which lacks the feature” is correct.

  The code only runs where the runtime supports it. Your laptop's Node.js 22 has the feature, but the server's Node.js 16 doesn't, so the code fails there. The fix is to match versions, for example by upgrading the server or pinning a version both use.

  • Pin it: an engines field in package.json or a .nvmrc file.
  • Test: on the same version as production before deploying.

📖 Revise: Module 3: Software and Applications

Why each option is right or wrong

• “The package is no longer maintained by its authors” (Incorrect): A new major version usually means active development, not abandonment.
• “It contains only small bug fixes for version 2” (Incorrect): Fix-only releases change the last (PATCH) number, like 2.9.5.
• “It's safe to upgrade because the number went up” (Incorrect): A higher number doesn't mean safe; a new major version is the one most likely to break things.
• “There may be breaking changes” is correct.

  Semantic versioning uses MAJOR.MINOR.PATCH. A change in the first number, from 2 to 3, signals changes that may break code written for version 2, such as removed or renamed functions. Read the release notes and test before upgrading.

  • Minor (2.10.0): new features, should stay compatible.
  • Patch (2.9.5): bug fixes only.

📖 Revise: Module 3: Software and Applications

Why each option is right or wrong

• “The domain's DNS settings for the office” (Incorrect): DNS turns names into addresses; it doesn't carry the file data being copied.
• “The internet provider's line into the office” (Incorrect): The files don't travel over the internet connection, so its speed doesn't matter here.
• “The antivirus software on the internet router” (Incorrect): Routers rarely scan local file copies; the speed is decided by the local network link.
• “The local network between them” is correct.

  Copying files between two desktops in the same office stays on the local network: the cables, switch or Wi-Fi between them. The internet connection isn't used, so a good speed test doesn't tell you anything about this. Check the local link, such as a slow Wi-Fi connection or an old cable.

  • Quick test: connect both by cable to the same switch.
  • Look for: 100 Mbps links where 1 Gbps is expected.

📖 Revise: Module 4: Computer Networks

Why each option is right or wrong

• “Browsers block sites hosted on home connections” (Incorrect): Browsers don't check what kind of connection a site uses; reliability is the issue.
• “Hosting a website over home broadband is illegal” (Incorrect): It isn't illegal, though some broadband terms discourage it; the real problem is reliability.
• “Ordinary PCs aren't able to run web server software” (Incorrect): Any computer can act as a server; the issue is reliability and speed.
• “Low upload speed, a changing address and no protection from cuts” is correct.

  Home broadband is built for downloading, so upload, which is what serving users needs, is often slow. The address can change, and a power or line cut takes the portal offline. Data centres provide steady uplinks, fixed addresses and backup power.

  • Better: a hosting plan or cloud server.
  • Also: an office PC adds security risks to the office network.

📖 Revise: Module 4: Computer Networks

Why each option is right or wrong

• “They see a warning, then your app” (Incorrect): There's nothing of yours to show behind the warning.
• “They see your app, because you share the same Wi-Fi” (Incorrect): Sharing Wi-Fi doesn't change what localhost means.
• “They see your app, but more slowly over Wi-Fi” (Incorrect): Their request doesn't reach your machine at all.
• “They don't see your app” is correct.

  localhost means "this computer". On your colleague's laptop, it points to their own laptop, where your app isn't running, so they get an error. To share, they'd need your computer's network address, and your app would have to accept connections from the network.

  • Your network address: looks like 192.168.1.20:3000.
  • Safer: deploy to a test server to share work.

📖 Revise: Module 5: IP Addresses and Ports

Why each option is right or wrong

• “Neither, and visitors use a VPN to reach the site” (Incorrect): A public website must be reachable without a VPN, on port 443.
• “Both 443 and 5432, so the app works from anywhere” (Incorrect): An internet-facing database invites attacks on your data; the app reaches it privately.
• “Only 5432, with the website served through it” (Incorrect): The website needs its own web port; the database port isn't for visitors.
• “Only 443” is correct.

  The website port, 443, must be public so visitors can reach it. The database port, 5432, should only be reachable by the app, usually on the same server or a private network. Exposing it invites password-guessing and attacks on your data.

  • Firewall: allow 443 (and 80 for redirects), plus SSH limited to you.
  • Database: listen on localhost or a private network only.

📖 Revise: Module 5: IP Addresses and Ports

Why each option is right or wrong

• “The site's HTTPS certificate expired an hour ago” (Incorrect): An expired certificate shows a warning, not "server not found", and it would affect mobile data too.
• “The office Wi-Fi blocks every website” (Incorrect): Then nothing else would work either, which wasn't reported.
• “The website was deleted by the hosting company” (Incorrect): It still works on mobile data, so it exists.
• “The office network still has the old DNS answer cached” is correct.

  DNS answers are cached for a time set by the record's TTL. The office network, or its router, may still hold the old answer from before your change, while mobile data asks a different resolver that already has the new one. Waiting, or clearing the cache, usually fixes it.

  • Check: with nslookup on both networks.
  • Before big changes: lower the TTL in advance.

📖 Revise: Module 6: How the Web Works

Why each option is right or wrong

• “The user's Wi-Fi and browser settings” (Incorrect): The server answered with a 500, so the connection worked; the fault is on the server.
• “The domain name's renewal date” (Incorrect): An expired domain wouldn't let other pages load.
• “The form's JavaScript validation in the browser” (Incorrect): Browser validation errors don't produce a 500; the server returned it.
• “The server's error logs for that request” is correct.

  A 500 error means the request reached the server, and the server's own code failed. Other pages work, so the problem is in the booking form's handling. The server's error log for that time shows the actual error and where it happened.

  • Look for: a stack trace with the file and line.
  • Then: reproduce it on a test copy and fix it.

📖 Revise: Module 6: How the Web Works

Why each option is right or wrong

• “Padlocks are only issued to verified companies” (Incorrect): Basic certificates are issued automatically to anyone who controls a domain.
• “It's probably your site on a backup domain” (Incorrect): You'd know your own domains; an unknown look-alike is a warning sign.
• “It's safe, because the padlock is valid” (Incorrect): A padlock says nothing about who owns the site.
• “The padlock proves encryption to that domain, not that it's yours” is correct.

  A padlock means the connection to that exact domain is encrypted. Anyone who controls a domain can get a valid certificate for it, including phishing sites with look-alike names. It doesn't prove the site belongs to you or is trustworthy. Check the domain itself.

  • Warning sign: a hyphen or extra word added to a real brand name.
  • Report: look-alike domains to the host or registrar.

📖 Revise: Module 6: How the Web Works

Why each option is right or wrong

• “The owner's home laptop, left switched on” (Incorrect): Unreliable: it sleeps, loses power and has a changing address.
• “A cluster across three cloud regions” (Incorrect): That complexity is for large, critical systems.
• “A dedicated server with a full-time admin” (Incorrect): Far more power and cost than 50 visitors need.
• “Simple shared hosting or a static site host” is correct.

  A small site with timetables and contact details needs little power. Shared hosting or a static site host is cheap, managed for you, and more than enough for 50 visitors a day. Bigger setups add cost and work with no benefit here.

  • Static site hosts: often include HTTPS and a CDN.
  • Grow later: if traffic or features change.

📖 Revise: Module 7: Servers and Hosting

Why each option is right or wrong

• “Nobody, since a VPS updates itself by default” (Incorrect): Many don't, unless you set up automatic updates, which is still your job.
• “The hosting company, as part of the plan” (Incorrect): Hosts maintain the hardware and network; the operating system inside your VPS is yours.
• “The developer who first built the website” (Incorrect): Whoever runs the server now is responsible, not whoever wrote the site years ago.
• “You, because the VPS's operating system is yours to maintain” is correct.

  With a VPS, the host runs the hardware and network, but the operating system inside is yours: updates, security patches and settings. An old system library left unpatched is the owner's responsibility. Turning on automatic security updates helps.

  • Ubuntu: unattended-upgrades for security patches.
  • Managed hosting: if you'd rather the host handle updates.

📖 Revise: Module 7: Servers and Hosting

Why each option is right or wrong

• “It needs sudo first, or it won't do anything” (Incorrect): Even without sudo it deletes every file you own; it's dangerous either way.
• “Nothing; it only deletes the build folder” (Incorrect): Each path is deleted separately, and / is the whole system.
• “It deletes the folder but leaves the files inside” (Incorrect): -r deletes the folder and everything in it.
• “The stray / targets the whole system” is correct.

  rm -rf deletes everything it's given, without asking. The space before / makes it a separate target: the root of the whole system. On many systems that would start deleting everything it can reach. Read every AI-suggested command before running it.

  • Safer: rm -rf ./build only, after checking the path.
  • Even safer: use the project's own clean script.

📖 Revise: Module 8: Developer Workstation Basics

Why each option is right or wrong

• “Make the repository private before pushing” (Incorrect): Private repos still get shared and cloned; secrets don't belong in code at all.
• “Rename the variable to something less obvious” (Incorrect): The value is still there for anyone to read.
• “Push now, then change the password later” (Incorrect): Once pushed, the old password stays in history, and bots scan GitHub within minutes.
• “Move it to an environment variable and keep .env out of Git” is correct.

  Anything committed to Git stays in the history, and once pushed to GitHub, anyone with access can read it. Put the password in an environment variable, load it from a .env file that's listed in .gitignore, and commit a .env.example with a placeholder instead.

  • Already pushed before? Change the password too.
  • Add: a secret scanner to catch mistakes.

📖 Revise: Module 8: Developer Workstation Basics

Why each option is right or wrong

• “git status” (Incorrect): It lists which files changed, but not the exact lines.
• “git stash” (Incorrect): That sets changes aside; it doesn't show what they are.
• “git log” (Incorrect): That lists past commits; it doesn't show uncommitted changes line by line.
• “git diff” is correct.

  git diff lists every line added or removed in your files since the last commit. After a big AI change, it's the way to review exactly what was touched before you commit or undo it.

  • Staged changes: git diff --staged.
  • Summary: git status lists which files changed.

📖 Revise: Module 9: Introduction to Git

Why each option is right or wrong

• “Wait, as Git resolves conflicts by itself after a while” (Incorrect): Git won't guess; a person has to choose.
• “Force-push your branch so your version wins” (Incorrect): That overwrites your teammate's work without deciding anything.
• “Delete the file and create it again from scratch” (Incorrect): That throws away both sets of changes.
• “Edit the file to the right version, then add and commit” is correct.

  Git marks the clash with <<<<<<<, ======= and >>>>>>>, showing both versions. You decide what the line should be, which may mean combining both changes, delete the markers, then git add and git commit to finish the merge. Talk to your teammate if you're unsure what they meant.

  • Editors help: VS Code shows 'Accept current / incoming / both' buttons.
  • Back out: git merge --abort returns to before the merge.

📖 Revise: Module 9: Introduction to Git

Why each option is right or wrong

• “Delete the file and write it again from scratch” (Incorrect): That loses both people's work.
• “Force-push your branch to overwrite the teammate” (Incorrect): That erases their work from the shared history.
• “Keep your own version, since you made it most recently” (Incorrect): You might throw away a correct change your teammate made.
• “Read both versions, decide the right result, and commit it” is correct.

  A conflict means Git can't tell which change is right, because both edited the same lines. A person must read both versions, decide what the final text should be, often combining them, and commit that. Talk to your teammate if you're unsure.

  • Editors: VS Code shows both versions with buttons to choose or combine.
  • Then: test the page before committing.

📖 Revise: Module 10: Working with GitHub