Computer Ports, Cables and Connectors: Types and Uses

The correct answer is C, eight. The RJ-45 connector is properly called 8P8C, meaning eight positions and eight contacts, and it is crimped on to the four twisted pairs of a network cable, one contact for each of the eight wires. It is the plug that fits the Ethernet port of a computer, a switch or a router. Option A is wrong because four contacts belong to the smaller RJ-11 telephone connector in its usual form. Option B is wrong because six positions also describe the RJ-11 housing, and the PS/2 mini-DIN socket has six pins, so six is the standard distractor here. Option D is wrong because fifteen is the number of pins on a VGA display connector, which has three rows of five and has nothing to do with networking.

The correct answer is A, Universal Serial Bus. The standard first appeared in 1996 and was meant to replace the many different ports of an older computer with one socket for every kind of peripheral. It is called serial because it sends one bit at a time, universal because the same port serves a keyboard, a printer, a camera or a storage device, and a bus because many devices share the one path, up to a hundred and twenty-seven of them through hubs. Option B is wrong because the middle word is serial, not system, and a system bus is the internal path between the processor and memory, a different idea altogether. Option C is wrong because the first word is universal, not unified. Option D is wrong because USB is not limited to storage, even though pen drives are its commonest use.

The correct answer is B, fifteen. The Video Graphics Array connector is a D-shaped plug with fifteen pins in three rows of five, usually coloured blue, and it carries an analogue video signal only, so a separate cable is needed for sound. Option A is wrong because nine pins belong to the DB-9 serial connector of the RS-232 standard, known to the operating system as the COM port. Option C is wrong because nineteen pins belong to the standard Type-A HDMI connector, which carries digital video and audio together; mixing up the fifteen of VGA with the nineteen of HDMI is the usual mistake in this question. Option D is wrong because twenty-five pins belong to the DB-25 parallel or LPT connector, which was used for printers on older computers.

The correct answer is C, HDMI. The High-Definition Multimedia Interface carries high-definition digital video and multi-channel digital audio in the same cable, which is why one HDMI lead is enough to join a computer to a television or a projector. Option A is wrong because the Video Graphics Array port carries an analogue video signal only and needs a separate audio cable, a difference that is asked again and again. Option B is wrong because the PS/2 port is a six-pin socket for a keyboard or a mouse and carries no video or audio at all. Option D is wrong because the serial port sends one bit at a time at low speed and was used for modems and instruments, not for display. DisplayPort is the other port that carries both video and audio, chiefly on computer monitors.

The correct answer is A, because that statement is the false one. Unshielded twisted pair cable has no metal foil or braid around its pairs, so it resists electromagnetic interference less well than shielded twisted pair, not better; the only protection it has is the twisting of each pair, which cancels much of the noise picked up by the two wires. Option B is a true statement, since UTP is the cable of almost every office and home local area network, in grades such as Cat 5e and Cat 6. Option C is also true: without the shield the cable is thinner, lighter and easier to bend around corners, which is one reason installers prefer it. Option D is true as well, because UTP is cheap to buy and to terminate and performs well over the hundred-metre segment that Ethernet allows.

The correct answer is B, the keyboard. 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. Plugging the devices into the wrong sockets leaves them unrecognised, which is why the colour code was introduced at all. Option A is wrong because the mouse socket is the green one, and this swap is exactly what the question tests. Option C is wrong because a printer was connected through the twenty-five-pin parallel or LPT port, and is connected through USB today; it never used a PS/2 socket. Option D is wrong because a microphone goes into the pink 3.5 millimetre audio jack, while green among the audio jacks means the speaker or line output, a second colour code worth learning separately.

The correct answer is B, the LPT port. 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. Being parallel, it sent eight bits at once over separate wires, which made it faster than a serial port over a short distance. Option A is wrong because COM, short for communication, was the name of the serial port, which used the nine-pin DB-9 connector and sent one bit at a time. Option C is wrong because the PS/2 port is the six-pin socket for keyboard and mouse. Option D is wrong because the Accelerated Graphics Port was an internal expansion slot for a graphics card on the motherboard, not an external port at all.

The correct answer is B, 480 megabits per second, the speed known as high speed in the USB 2.0 specification. Option A is wrong because twelve megabits per second was the full-speed rate of USB 1.1, forty times slower, with a low-speed mode of one and a half megabits per second for devices such as a mouse. Option C is wrong because five gigabits per second is the SuperSpeed rate of USB 3.0, whose connector is usually coloured blue so that it can be told apart from a 2.0 socket. Option D is wrong because ten gigabits per second belongs to the generation after USB 3.0. The figures to carry into the examination hall are therefore twelve for 1.1, four hundred and eighty for 2.0 and five thousand, that is five gigabits, for 3.0.

The correct answer is D, optical fibre cable. 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. That is also why fibre offers the highest bandwidth, loses least signal over distance and is very hard to tap without being detected. Option A is wrong because unshielded twisted pair relies only on the twisting of its pairs to cancel noise and is the most vulnerable of the four. Option B is wrong because the foil or braid of shielded twisted pair reduces interference but does not remove it. Option C is wrong because the braided shield of coaxial cable likewise reduces interference without making the cable immune, as the signal is still electrical.

The correct answer is B, a telephone or dial-up modem line. 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. Option A is wrong because Ethernet uses the wider RJ-45 connector with eight contacts; an RJ-11 plug will not hold in an RJ-45 port, and confusing the two is the commonest mistake in this part of the syllabus. Option C is wrong because a monitor is connected through VGA, DVI, HDMI or DisplayPort. Option D is wrong because a hard disk inside the cabinet is connected by a SATA data cable of seven pins, or by the older forty-pin IDE ribbon cable, neither of which uses a modular telephone connector.

The correct answer is B, coaxial cable. 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. It is seen on older network cabling, on television and on test instruments. Option A is wrong because twisted pair cable ends in the modular RJ-45 connector for Ethernet or RJ-11 for telephone lines. Option C is wrong because optical fibre uses SC, ST and LC connectors, which align the fibre core precisely so that light passes across the joint. Option D is wrong because a SATA data cable has its own flat seven-pin keyed connector that plugs into the drive and the motherboard, and is used only inside the cabinet.