Wi-Fi
The 802.11 generations, bands and their channels, SSID and BSSID, a station joining an access point, CSMA/CA and the hidden node, and the WEP, WPA, WPA2 and WPA3 protections.
- 27 cards
- 7 topics
- Free
The outline, topic by topic
Each topic is weighted the way the exam weighs it.
- Concepts
- Questions
- Sort and link
- The numbers
- On the diagram
- Scenarios
- Understand
A few cards from the deck
SSID: what is it?
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The name of the wireless network, chosen by the administrator, which several access points can share to form a single network.
What tells each access point apart is its BSSID, the MAC address of its radio. A host on the move goes from one BSSID to another while keeping the same SSID.
A company wants laptops to move from one access point to another without reconnecting. What must the access points share?
- The SSID and the security, with different BSSIDs
- The same BSSID and the same channel on each access point
- The same IP address, so the host does not change gateway
- Only the band, whatever the network name
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The SSID and the security, with different BSSIDs
The host picks among the access points that announce its SSID with the same security. Two access points cannot share a BSSID: it is their radio's MAC address, unique by definition.
In 2.4 GHz, the classic plan of three channels that do not overlap is ….
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In 2.4 GHz, the classic plan of three channels that do not overlap is 1, 6 and 11.
Channels are spaced 5 MHz apart but about 22 MHz wide: two access points on channels 3 and 4 interfere, whereas 1, 6 and 11, five numbers apart, coexist.