Computer Quiz — 50 Questions, Ending in Why It Got Slow

What does the CPU do?

Answer Carries out the instructions that make up a program

The processor does nothing clever on its own — it fetches an instruction, carries it out, and moves to the next, billions of times a second. Everything a computer appears to do is that loop repeated fast enough to look like thought.

What happens to what is in RAM when the power goes off?

Answer It is lost

RAM is volatile: cut the power and it empties. That is why unsaved work disappears in a crash, and why the first advice after a freeze is to save, not to restart.

What is stored on a solid-state drive that is not stored in RAM?

Answer Files and programs that must survive a restart

The drive keeps what must survive a restart. RAM is the desk you work on and the drive is the filing cabinet — the desk is far faster but gets cleared every night.

What is a GPU mainly for?

Answer Doing many similar calculations at once, such as drawing images

A GPU has thousands of simple cores instead of a few complex ones, so it excels at doing the same operation to many values at once. That is why the same chip suits graphics, video and machine learning.

What does a motherboard do?

Answer Connects the components so they can communicate and receive power

The motherboard is the wiring, not a component that computes. Its main constraint is compatibility: the socket and chipset decide which processors and memory will physically fit.

Why do processors have several cores?

Answer To work on several streams of instructions at the same time

One core can only follow one stream of instructions at a time. More cores let several run at once, but a program written for a single stream gains nothing — which is why core count alone predicts very little.

What does a cooling fan actually protect against?

Answer Components slowing down or shutting off when they get too hot

Heat does not usually break a modern chip; it makes it slow down on purpose. Thermal throttling is a protection, so a dusty fan shows up as a machine that is gradually less fast rather than one that fails.

What is firmware?

Answer Software stored in a device that controls the hardware itself

Firmware is software that lives inside a device and controls the hardware itself. It sits below the operating system, which is why a firmware update can change how a router or a drive behaves at a level no app can reach.

What is the practical difference between a wired and a wireless keyboard?

Answer The wireless one needs power of its own and a receiver or pairing

Wireless means batteries and a radio link — a receiver or Bluetooth. That adds a little delay and a component that can fail, in exchange for no cable. Wired keyboards need nothing but the port.

What does the screen's resolution describe?

Answer How many pixels it displays

Resolution counts pixels, not physical size. A small phone screen can have more pixels than a large monitor, and that is why the same image looks sharper on the phone.

How many bits are in a byte?

Answer Eight

Eight bits, which gives 256 possible values — enough for one character in older text encodings. That is the historical reason a byte is the unit files are measured in.

What does a file extension such as .txt or .png tell the system?

Answer What kind of file it is, so the right program opens it

The extension is only a naming convention; the bytes inside do not change when you rename a file. The system uses it to pick a program, which is why renaming a photo to .txt makes it open as gibberish rather than converting it.

What is lost when an image is saved in a lossy format?

Answer Detail the format judges you are unlikely to notice

Lossy formats discard detail they judge you will not miss, and the loss is permanent. Saving the same JPEG repeatedly degrades it a little each time, which is why editing should be done from an original.

What does a folder actually contain?

Answer References telling the system where those files are

A folder holds references, not the files themselves. That is why moving a folder on the same drive is instant while copying it to another drive takes time — one rewrites a list, the other moves the data.

Why can a text file be far smaller than a photo of the same text?

Answer Because the photo stores a color value for every pixel, not the characters

A text file stores the characters; a photo stores a color value for every pixel, including all the white space around the letters. The photo is recording an image of the text rather than the text.

What normally happens when you delete a file without emptying the bin?

Answer It is moved, and the space is not reclaimed until the bin is emptied

Deleting normally moves the file to the bin and reclaims nothing. Even after emptying it, the data usually remains on the drive until something overwrites it — which is why deletion is not the same as erasure.

What does a backup protect you from that a sync service alone does not?

Answer A file being deleted or damaged, because a backup keeps an older copy

Sync copies your mistakes. Delete a file and the deletion propagates to every device within seconds; a backup keeps older versions, so there is something to go back to.

What is a zip file?

Answer One file containing others, usually compressed

A zip is a container holding other files, usually compressed. Compression works by finding repetition, which is why text shrinks dramatically and an already-compressed photo or video barely shrinks at all.

Roughly how many megabytes are in a gigabyte?

Answer One thousand

About a thousand — and the ambiguity is real. Drive makers count 1,000 megabytes to a gigabyte while operating systems often count 1,024, which is why a new drive always shows less capacity than the box promised.

Why does a file sometimes open as unreadable characters?

Answer Because the program is interpreting the bytes with the wrong format or encoding

The bytes are being interpreted with the wrong character encoding. Nothing is damaged: the same file opened with the right setting reads normally, which is why the fix is a menu option rather than a repair.

What does a domain name system server do?

Answer Turns a name like example.com into an address a machine can connect to

DNS translates a name into an address. It is also why a site can appear down for you and fine for someone else — you may be asking a different DNS server, or holding an out-of-date answer in cache.

What is the difference between wifi and the internet?

Answer Wifi is the wireless link to your router; the internet is what the router connects to

Wifi is only the last few meters, the radio link between your device and the router. You can have a perfect wifi signal and no internet at all, which is exactly what the two-bar-but-nothing-loads situation is.

What does the padlock in a browser's address bar indicate?

Answer The connection to the site is encrypted

The padlock means the connection is encrypted, not that the site is trustworthy. Certificates are free, so a phishing page has one too — it tells you nobody is listening in, not who is at the other end.

What is an IP address?

Answer A number identifying a device on a network

An IP address identifies a device on a network. Most home devices have a private address behind the router and share one public address, which is why sites see your household as a single visitor.

What does a router do?

Answer Directs traffic between your devices and the wider network

The router directs traffic between your devices and the wider network, and it is also usually the firewall and the wifi access point in the same box. Most home connection problems are in that box rather than beyond it.

What does a browser cache hold?

Answer Copies of files from sites you visited, so they load faster next time

The cache holds copies of files already downloaded, so a repeat visit does not fetch them again. That is also why clearing the cache fixes a page stuck on an old version, and why the next load is slower.

What is bandwidth?

Answer How much data can move per second

Bandwidth is how much data can move per second — the width of the pipe. It is what internet plans advertise, and it is only half the story.

Why can a connection have high bandwidth and still feel slow in a game or call?

Answer Because latency, the delay of each round trip, is separate from bandwidth

Latency is the other half: how long each round trip takes. A wide pipe with slow round trips is fine for downloading a large file and bad for a call or a game, where the delay is what you feel.

What does a cookie stored by a site do?

Answer Holds a small piece of data the site uses to recognize your browser later

A cookie is a small piece of data the site asks your browser to store and send back, which is how a site remembers you are signed in. The mechanism is neutral; what matters is who is setting them and what they record.

What does a URL's first part, such as https, specify?

Answer The protocol used to fetch the page

The first part names the protocol — the set of rules for the exchange. It is why https and http can reach the same server yet differ entirely in whether the traffic is readable along the way.

Why is reusing one password across sites risky?

Answer One site's breach hands out the key to all the others

Attackers take usernames and passwords from one breach and try them everywhere else, automatically. It is called credential stuffing, and it is why one leaked site can cost you an email account you never registered there.

What makes a passphrase of several unrelated words strong?

Answer Its length gives it far more possible combinations to search

Length adds possibilities much faster than complexity does. Several unrelated words are far harder to guess than a short password full of symbols, and far easier for a person to remember.

What does two-factor authentication add?

Answer A second, different proof of identity beyond the password

The second factor is something other than knowledge — a device, an app, a key. It matters because a stolen password alone then buys nothing, which defeats the most common kind of attack.

Why do software updates matter for safety?

Answer They close flaws that are already known and being exploited

Most attacks use flaws that are already public and already patched. Updating is not about new features; it is about closing doors that attackers already know are there.

What is the point of the three-copy rule for backups?

Answer Copies in different places survive an accident that destroys one place

Three copies, on two kinds of media, with one off site. The point is that a single accident — a fire, a theft, a bad sync — should never be able to reach all of them at once.

What does a password manager mainly solve?

Answer Having to remember a different strong password for every site

It removes the reason people reuse passwords. Remembering one strong passphrase and letting the manager generate the rest turns the hardest security habit into an easy one.

Why is public wireless a poorer place to sign in to important accounts?

Answer You have less control over the network between you and the site

You have no control over the network between you and the site. Encrypted connections cover most of the risk now, but the network can still see which sites you visit and can interfere with anything not encrypted.

What does encryption of a laptop's drive protect?

Answer The data if the machine is lost or stolen

Encryption protects data when the machine is out of your hands. A password only stops someone logging in; without encryption the drive can be removed and read directly.

What is the safest general rule about software downloads?

Answer Get it from the maker's own site or an official store

Get software from the maker's own site or an official store. Search results and download portals are where bundled and altered installers live, and the file often looks identical.

Why do accounts ask for a recovery method?

Answer So you can get back in if you lose the password or the device

Recovery exists so a forgotten password does not cost you the account. It is also a way in for an attacker, which is why the recovery address deserves the same protection as the account itself.

A machine slows down whenever many tabs are open. What is most likely short?

Answer Memory

When memory runs out the system starts swapping to the drive, which is far slower. That is what makes a machine feel sluggish and busy at the same time, and it is the classic sign of needing more RAM.

What does restarting actually do that closing a program does not?

Answer It clears everything held in memory and reloads the system from scratch

Restarting clears everything held in memory and reloads the system from scratch. Closing a program leaves drivers, background services and leaked memory in place, which is why restarting fixes things closing does not.

Why do so-called cleaner programs rarely help?

Answer The temporary files they remove were rarely what was slowing anything down

The temporary files they delete were rarely costing you anything, and modern systems clean up after themselves. Many such programs also charge for the privilege or install more than they remove.

A laptop is fast for a minute and then slows down under load. What does that pattern suggest?

Answer It is heating up and reducing its own speed to stay cool

Fast then slow under load is the signature of heat. The machine is protecting itself by reducing speed, so the fix is airflow and dust rather than a faster processor.

Why does a nearly full drive slow a system down?

Answer The system needs free space to work in, and has less room to organize data

The system needs free space to work in — for swapping, for temporary files, and for rearranging data. A drive close to full also has fewer places to put new data, which makes writing slower.

The whole machine is fine but one website crawls. Where should you look first?

Answer That site or the connection to it, not the computer

If everything else is normal, the problem is that site or the path to it. Checking one other site takes seconds and tells you immediately whether to keep looking at your own machine.

What does adding more RAM not fix?

Answer A single task limited by processor speed

More memory does not make a single task run faster if that task is waiting on the processor. RAM removes a queue; it does not raise the speed limit.

Why does a machine take longer to start after years of use?

Answer More programs have been set to launch at startup

Programs add themselves to startup over the years, and each one wants a share of a machine that is still waking up. Reviewing that list usually helps more than any cleanup tool.

What is the sensible first step when a program keeps freezing?

Answer Check whether the program and the system are up to date, and restart

Check whether the program and the system are up to date. Freezes are often known bugs already fixed, and it costs nothing to rule that out before anything more drastic.

Someone says their internet is slow but only on one device. What does that tell you?

Answer The problem is likelier on that device or its link to the router than in the service

If one device is slow and the others are fine, the shared connection is unlikely to be the cause. Look at that device — its wifi signal, its updates, what it is running — before calling the provider.