Computer Awareness GK Questions with Answers – Page 8

SSL was developed by Netscape in the mid-1990s to encrypt the traffic between a web browser and a web server, and its successor, Transport Layer Security or TLS, standardised from 1999, is what actually protects websites now; the older name survives in common speech and in the phrase SSL certificate.

The defining feature of symmetric encryption is that a single shared secret key performs both operations: the sender encrypts the plaintext with it and the receiver decrypts the ciphertext with the very same key.

Symmetric encryption uses one shared secret key for both locking and unlocking data, and because it is the older and simpler of the two families it is variously called conventional, secret key or private key encryption.

A barcode must be presented squarely to a scanner, one item at a time, and a torn or dirty label fails.

A Bluetooth link does not stay on one frequency. Master and slave agree on a pseudo random sequence and jump together between the narrow channels of the 2.4 GHz band many hundreds of times a second.

Infrared communication, the old IrDA link of television remote controls and early mobile phones, uses light just beyond the red end of the visible spectrum.

WPA3 is the newest of the four and the strongest; it replaces the old pre shared key handshake with simultaneous authentication of equals, which resists offline guessing of the password, and it encrypts traffic even on an open network.

The technology is named after Harald Gormsson, the tenth century king of Denmark nicknamed Bluetooth, who brought the Danish tribes under one rule.

A FASTag is a battery free RFID sticker pasted on the inside of the windscreen. An overhead reader at the toll plaza energises it, reads the identity number, matches it with the linked prepaid wallet or bank account and debits the toll while the vehicle keeps moving.

A passive tag is only a chip and an antenna. When it enters the field of a reader, the incoming radio waves induce a current in the antenna, that current powers the chip for an instant, and the chip replies by modulating the reflected signal, a method called backscatter.

NFC is built on the high frequency band of radio frequency identification and uses magnetic induction between two loop antennas at 13.56 MHz, which is why the devices must be brought within about four centimetres of each other.

In a piconet one device acts as the master and sets the clock and the hopping sequence, and up to seven other devices can be active slaves at the same time, which makes eight devices in the piconet in all.

The 802.15 group of standards covers wireless personal area networks, and 802.15.1 is the one that was drawn from the Bluetooth specification; the technology itself is now developed by the Bluetooth Special Interest Group.

Wi-Fi operates in the unlicensed industrial, scientific and medical bands, and the two classic bands are 2.4 GHz and 5 GHz, with 6 GHz added in the latest equipment.

The BNC connector is the bayonet-fitting plug that is pushed on and given a quarter turn to lock, and it terminates a coaxial cable, the cable with a central copper conductor, an insulating layer, a braided metal shield and an outer jacket.

The RJ-11 is the small modular connector at the end of a telephone cord, with four or six positions and usually two or four contacts, and it was also used to join a dial-up or ADSL modem to the telephone line.

Fibre carries data as pulses of light travelling through a glass or plastic core by total internal reflection, and since no electric current flows in it, an external electromagnetic field cannot induce noise in the signal.

The correct answer is B, 480 megabits per second, the speed known as high speed in the USB 2.0 specification.

LPT stands for line print terminal, the name by which the operating system knew the parallel port, which used a twenty-five-pin DB-25 connector on the computer and a thirty-six-pin Centronics connector at the printer end.

A computer with PS/2 ports has two six-pin mini-DIN sockets that are identical in shape, so they are distinguished by colour: purple for the keyboard and green for the mouse.