backstage knowledge

Question 1

what is a hash?

Answer 1

one-way cryptographic function that turns any input into a fixed-length output (called a digest). hashes are irreversible and unique to each data input.

Question 2

what is salting?

Answer 2

random data added to a password before it’s hashed. prevents rainbow attacks by making every hash unique, even for users w the same password

Question 3

what is plaintext?

Answer 3

unencrypted, readable data. opposite of ciphertext

Question 4

what is ciphertext?

Answer 4

the scrambled, unreadable output of encrypted plaintext. requires a key to decrypt back to plaintext

Question 5

what is a MAC address?

Answer 5

media access control address
- hardware id that uniquely identifies a device on a local network

looks like: A4:B2:C1:9D:34:12

• used by switches for directing traffic on a LAN

dance metaphor: dancer’s costume tag – unique to the dancer (device)

Question 6

how does ARP work?

Answer 6

used within local networks to map IP addresses to mac addresses

1. device says “hey! who has ip xxx.xxx.x.x?
2. the device with that ip responds: ME! my mac address is: AA:BB:CC:DD:EE:FF.
3. now the first device knows how to send the data directly on the local network.

***NOTE: doesn’t authenticate!!!

Question 7

what is a DNS server?

Answer 7

• the internet’s phone book.
• translates domain names like google.com into IP addresses

Question 8

what is a switch?

Answer 8

A device used inside a LAN to connect multiple devices together – eg laptop, printer, and desktop

• directs traffic based on mac addresses, NOT ip

Question 9

what is a router?

Answer 9

a device that connects different networks together and routes traffic from your local network to the internet and back.

• decides where packets go based on IP addresses
• sits between home network and ISP

Question 10

what is a recursive resolver?

Answer 10

• a dns helper service that takes a client request “where is google.com?” and keeps asking other DNS servers (root -> TLD > authoritative) until it finds an answer.
• usually managed by your isp or a public service like google dns or cloudflare

Question 11

what is a port?

Answer 11

a door or mailbox on software where specific types of network traffic are received

80= HTTP
25 = email sending (STMP)
443 = HTTPS

Question 12

what are 1.1.1.1 and 8.8.8.8?

Answer 12

they are public dns resolver ip addresses - like public internet phone books anyone can use. eg cloudflare, google, quad9

Question 13

what is the OSI model?

Answer 13

open systems interconnection model

• conceptual framework for describing how data moves thru a network. 7 layers:

1. physical - cables, signals
2. data link - mac addresses, ethernet
   (ARP maps MAC addresses to IP addresses here - translates between layers 2/3)
3. network - ip addresses, routing
4. transport - tcp/udp
5. session - session establishment
6. presentation - encryption, encoding
7. application - what you see - browsers

Question 14

what is the difference bretween a virus and worm?

Answer 14

virus: needs a host file or user interaction

worm: self-contained and self-spreading

Question 15

what is cache?

Answer 15

Cache is a small, fast memory that stores frequently used data to make future access quicker.

Question 16

What is the purpose of a modem?

Answer 16

A modem (MOdulator-DEModulator) converts digital data from a computer into analog signals for transmission over phone or cable lines — and vice versa.

Question 17

Where does a modem sit in a home or small office network?

Answer 17

It connects your internal network (via a router or directly to devices) to your Internet Service Provider (ISP).

Question 18

Is a modem physical or software-based?

Answer 18

It’s a physical device with embedded software/firmware.

Question 19

What layer of the OSI model does a modem operate at?

Answer 19

Mostly Layer 1 (Physical) and Layer 2 (Data Link) — it deals with transmitting raw bits over physical mediums.

Question 20

What are the 3 major types of cache?

Answer 20

1. CPU Cache – tiny, ultra-fast memory between CPU and RAM
   
   2. Web Browser Cache – stores copies of web pages, images, etc., to speed up browsing
   3. DNS Cache – stores previously resolved IP addresses to avoid new DNS lookups

Question 21

Is cache hardware or software?

Answer 21

Both — CPU cache is hardware, but browser and DNS cache are software-based memory stores.

Question 22

What is the risk of cache in cybersecurity?

Answer 22

Outdated or poisoned cache can serve malicious data (e.g., DNS cache poisoning), or leak sensitive info (e.g., browser cache exposing passwords).

Question 23

1. What happens when you type a URL?

Answer 23

1. Check browser cache
   
   2. Ask recursive DNS resolver
   3. Resolver asks root → TLD → authoritative server
   4. Get IP, send TCP request
   5. TLS handshake (if HTTPS)
   6. Server sends web content
   7. Browser displays page

Question 24

TLS

Question 25

TCP

Question 26

What is a port and why does HTTPS use 443

Answer 26

A port is a logical door on a device that handles specific types of traffic. • Think of your device as a hotel. The IP address is the hotel address, and the port is a room number where a service lives (e.g., room 443 = secure web traffic). • Port 443 is the default for HTTPS (encrypted web traffic using TLS).

Question 27

What’s the difference between a router, switch, and modem?

Answer 27

Device Role Analogy Modem Converts ISP signal to digital Translator between languages Router Routes traffic between networks Mailroom that knows ZIP codes Switch Connects local devices together Internal office mail sorter You need all three for full internet access in a home or office.

Question 28

How does DNS resolve a domain

Answer 28

DNS (Domain Name System) translates human-readable domain names into IP addresses. Resolver’s job: • Your device asks: “What is the IP for bubble.io?” • If not cached, the recursive resolver queries: 1. Root server → “Ask .io server” 2. .io TLD server → “Ask bubble.io authoritative server” 3. Authoritative DNS → “Here’s the IP: 198.51.100.25” • Your device connects to that IP.

Question 29

How does DNS resolve a domain?

Answer 29

DNS (Domain Name System) translates human-readable domain names into IP addresses. Resolver’s job: • Your device asks: “What is the IP for bubble.io?” • If not cached, the recursive resolver queries: 1. Root server → “Ask .io server” 2. .io TLD server → “Ask bubble.io authoritative server” 3. Authoritative DNS → “Here’s the IP: 198.51.100.25” • Your device connects to that IP.

Answer 30

Protocol TCP UDP Full Name Transmission Control Protocol User Datagram Protocol Connection? Yes (handshake + guaranteed delivery) No (fire and forget) Reliable? Yes No Speed? Slower Faster Used for Web browsing, email Video calls, games, live streams