Networking Basics
Networking is how computers communicate. In cybersecurity, networking matters because most attacks arrive over a network: email, websites, downloads, and remote connections.
What is a network?
A network is two or more devices connected so they can exchange data. Your home Wi-Fi is a local network. The internet connects millions of networks together.
LAN vs WAN
- LAN (Local Area Network): your home or office network
- WAN (Wide Area Network): networks connected over large distances (the internet)
IP addresses (who is who)
An IP address identifies a device on a network—like a mailing address. Data sent to the wrong IP goes to the wrong destination.
DNS (names → numbers)
DNS converts human-friendly names (example.com) into IP addresses. Users remember names. Networks route using numbers.
Ports (which “door”?)
If an IP address is a building, a port is a specific door. Different services “listen” on different ports.
Request → Response (what “traffic” really is)
Your device (client) sends a request (ex: load a website) and a server sends a response (the content). That back-and-forth is network traffic.
Protocols (the rules)
A protocol is a set of rules devices use to communicate. Common examples:
1HTTP / HTTPS
Web browsing. HTTPS is the secure version.
2DNS
Translates domain names to IP addresses.
3SMTP
Commonly used for sending email between mail servers.
4DHCP
Automatically gives devices IP addresses on a network.
Common beginner mistakes
- Thinking Wi-Fi and the internet are the same thing
- Thinking DNS stores websites (it stores name → IP lookups)
- Thinking ports are physical plugs (they’re logical “doors”)
Lesson 3 Summary
- LAN is local; WAN is global
- IP identifies the device
- DNS translates names to IPs
- Ports identify services
- Traffic is request + response
- Protocols are the rules
Practical: “Traffic Triad”
For each scenario, pick the best cyber lens: Who (IP), What (Port), or How (Protocol).
Click the best lens for each scenario
Scenario 1: “Is this website traffic encrypted?”
You’re deciding whether traffic is protected in transit.
Scenario 2: “Why won’t the service connect?”
The device is reachable, but the service won’t respond.
Scenario 3: “Which device is communicating?”
You’re identifying the sender/receiver of traffic.
Scenario 4: “Why won’t the name resolve?”
example.com won’t translate to an IP address.
Scenario 5: “Firewall blocked a service”
A connection is blocked unless a specific service is allowed.
Scenario 6: “Suspicious traffic source”
You need to know where the traffic originated.
Lesson 3 Quiz
Grade the quiz to see feedback. Next lesson unlocks at 75%+.
A home Wi-Fi network is an example of what?
What does DNS do?
In the “building and doors” analogy, what does a port represent?
What is network “traffic”?
What is the best one-sentence definition of a firewall?
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