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

NFC — Near Field Communication — is the very short range wireless technology behind contactless payments, transit cards, and badge readers. Its defining characteristic is the one in its name. NFC works at roughly 4 centimetres. That extremely short range is not a limitation — it is the security model. You have to deliberately bring two devices almost into contact. That physical requirement is what makes tap-to-pay acceptable, and it is why NFC questions on exams keep coming back to range. The Technical Facts Frequency: 13.56 MHz , the same band as high-frequency RFID. Range: about 4 cm in practice, with a theoretical maximum near 10 cm. Data rate: 106, 212 or 424 kbps. Slow, which is why NFC is often used to bootstrap a faster connection rather than carry the data itself. Standards: ISO/IEC 14443 and ISO/IEC 18092, governed by the NFC Forum. Power: a passive tag needs no battery. The reader's field induces enough current to power it, which is why a transit card ...

GPS tagging — usually called geotagging — embeds location coordinates into a file's metadata when it is created. Every modern phone does it to photographs by default, recording latitude, longitude and often altitude alongside the timestamp. The location is not visible in the picture. It travels inside the file, and it survives being emailed, uploaded and shared. That invisibility is the entire security problem. Someone who would never post their home address will happily post a photograph taken in their living room, not realizing the two are equivalent. Where the Data Lives Photographs carry metadata in EXIF — Exchangeable Image File Format. Beyond GPS coordinates, a typical EXIF block holds the camera make and model, lens, exposure settings, the exact date and time, the device's serial number in some cases, the software used to edit it, and a thumbnail that occasionally survives cropping and reveals the uncropped original. Related metadata standards are IPTC and ...