CompTIA Exam Prep - ITF+, A+, Network+, Security+, CySA+

RSSI stands for Received Signal Strength Indicator . It is the measurement your device reports for how strong a wireless signal is at the receiver, and it is the number behind the bars in the corner of your screen. RSSI is expressed in dBm, it is always negative, and closer to zero is better. -45 dBm is excellent. -85 dBm is nearly unusable. That negative-number convention trips people up constantly, so it is worth sitting with. The unit is decibel-milliwatts — a logarithmic measure of power relative to one milliwatt. Wi-Fi signals are a tiny fraction of a milliwatt by the time they reach your laptop, so the value is always below zero. -50 is stronger than -75 , because -50 is the larger number. Reading the Scale RSSI Quality What works -30 to -50 dBm Excellent Everything. You are close to the access point. -50 to -60 dBm Very good HD video, voice, large transfers. The target for most designs. -60 to -67 dBm Good Reliable for most use. -67 dBm is the usual design minimum f...

Four wireless identifiers, similar names, and a genuine risk of muddling them on exam day. They are actually straightforward once you see that two are names and one is an address . SSID is the network's name. BSSID is a specific radio's MAC address. ESSID is the same name shared by several access points so you can roam. SSID — Service Set Identifier The human-readable network name, up to 32 characters, that appears in your device's list of available networks. "CoffeeShop-Guest", "HOME-A4B2". It is case sensitive, and it is broadcast in beacon frames roughly ten times a second so clients can find the network. SSIDs are not unique. Nothing stops two unrelated networks using the same name, which is exactly what an evil twin attack exploits. BSSID — Basic Service Set Identifier The MAC address of the access point's radio . Unlike the SSID, it is genuinely unique and it identifies one specific radio rather than a network. Two details matter...

Bluetooth is short range, which creates a false sense of safety. An attacker has to be nearby — but "nearby" means the next table in a coffee shop, the seat behind you on a train, or a car in the parking lot with a directional antenna, which extends the practical range well beyond the ten metres people assume. Bluetooth attacks are mostly attacks on pairing. Get the pairing wrong and everything above it is exposed. The Named Attacks CompTIA tests these by name, and the names are unfortunately similar, so the distinction matters. Bluejacking — sending an unsolicited message to a nearby Bluetooth device. It is a nuisance rather than a compromise: no data is taken and no control is gained. The memory hook is jacking = junk mail . Bluesnarfing — stealing data from a device over Bluetooth without authorization: contacts, messages, calendar entries, files. This one is a genuine breach. The hook is snarfing = stealing . If you learn nothing else here, learn that pair....