AP® Cybersecurity · Start here if networks are new
Networking Basics
Unit 3, Securing Networks, assumes you already know how data moves across a network. These three short sessions, about 60 minutes in total, teach only the networking that Unit 3's CED statements rely on: hosts and packets, the devices that move them, the addresses inside them, and how wireless networks announce themselves.
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Session 1 · 20 min
Networks: hosts, packets and the devices that move them
A network is a set of devices, called hosts, connected so they can exchange data.
What you will be able to do
- Distinguish a local area network, a wide area network and the internet.
- Identify hosts, servers and network data ports, and explain why an open data port is a risk.
- Distinguish the internal network from external networks and locate the boundary between them.
- Identify a packet's header and payload, and distinguish a packet from a frame.
- Describe the role of a switch, a router, a wireless access point and a firewall, and identify the default gateway.
Start session →
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Session 2 · 25 min · simulator inside
Addresses: MAC, IP, ARP, DNS and ICMP
Every connected device has two addresses: a media access control (MAC) address, which names its network card on one local link, and an internet protocol (IP) address, which locates it across networks.
What you will be able to do
- Describe a MAC address and distinguish it from an IP address.
- Identify the network portion, range and broadcast address of a /24 network, and classify an address as private or public.
- Explain how ARP pairs IP and MAC addresses, and how ARP poisoning redirects traffic and is detected.
- Explain how DNS turns a name into an IP address, and how DNS poisoning leads to credential harvesting.
- Describe ICMP and ping, and explain a smurf attack.
Start session →
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Session 3 · 15 min
Wireless basics: access points, SSIDs and beacon frames
A wireless access point connects devices to the wired local area network (LAN) by radio and announces the network's name, its service set identifier (SSID), in beacon frames several times a second.
What you will be able to do
- Describe how a wireless access point announces and provides a network.
- Explain why a signal that reaches beyond the building is a risk, and how organizations limit it.
- Recognize an evil twin, a rogue access point and a jamming attack, and how each is detected.
Start session →
You are ready for Unit 3 when you can
- explain why an open network data port or a signal outside the building lets an adversary reach the LAN;
- say which parts of a captured packet an adversary can read when the payload is encrypted;
- tell a switch from a router, and find the default gateway;
- read a /24 address range and spot its broadcast address;
- explain how ARP poisoning and DNS poisoning work, and the sign that detects each;
- tell an evil twin from a rogue access point.
Everything else in Unit 3, such as firewalls, segmentation and wireless encryption, is taught inside the Unit 3 topics themselves.