Computer Awareness Mixed Quiz: Set 38

The correct answer is C, conventional encryption. 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. Option A, public-key encryption, is the opposite arrangement: it uses a pair of keys, a public one that may be shared freely and a private one that is never shared. Option B, asymmetric encryption, is just another name for that same public-key family, so it too is the opposite of what the question asks. Option D, hybrid encryption, describes the practical combination used on the internet, where an asymmetric exchange settles a symmetric session key that then carries the data; it is not a synonym for symmetric encryption. DES, Triple DES and AES are the standard symmetric examples, while RSA and Diffie-Hellman are asymmetric.

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 D, both A and C. In an auction the price is not fixed by the seller but is discovered from what buyers are willing to bid, and this way of trading appears at two levels. Between businesses, industrial exchanges and procurement portals run reverse auctions and dynamic pricing for bulk material, which is B2B commerce, so option A is part of the answer. Between individuals, classified and auction platforms let one consumer bid for goods another consumer is selling, which is C2C commerce, so option C is also part of the answer. Option B, C2B commerce, is where an individual supplies a service or content to a firm, as a freelancer or a stock photographer does, and the price there is normally negotiated rather than auctioned. Because both the business-to-business and the consumer-to-consumer levels fit, the combined option D is right.

The correct answer is C, IEEE 802.15.1. 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. Option A, IEEE 802.3, is Ethernet, the wired local area network standard that uses twisted pair or fibre cable, so it is not wireless at all. Option B, IEEE 802.11, is Wi-Fi, a wireless local area network reaching tens of metres through an access point, a different scale of network from Bluetooth's personal area. Option D, IEEE 802.16, is WiMAX, intended for wireless broadband across a metropolitan area. A quick way to remember the set is 802.3 wired LAN, 802.11 Wi-Fi, 802.15.1 Bluetooth, 802.15.4 Zigbee and 802.16 WiMAX.

The correct answer is B, one key. 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. That is also its practical problem, because the key must be delivered to the other party over some safe channel before any message can be exchanged. Option A, two keys, describes asymmetric or public key encryption, where a public key and a private key form a linked pair. Option C, no key, describes a hash function such as MD5 or SHA-256, which produces a fixed-length digest without any key and cannot be reversed; hashing is therefore not encryption at all. Option D, three keys, is a distractor built on the name Triple DES, which in fact applies the DES algorithm three times and is still symmetric.

The correct answer is C, shareware. Shareware follows the try before you buy model: the publisher lets anyone download and use the program for a trial period, or in a version with some features locked, and asks for payment or registration if the user wants to go on. WinZip and WinRAR are the examples most often quoted. Option A is wrong because freeware never asks for payment at all, however long it is used. Option B is wrong because public domain software has no copyright holder to charge a fee. Option D is wrong because open source software is identified by an open source code rather than by a payment model; most open source programs are free, and none of them locks features behind a trial clock in the way shareware does. Remember shareware by the word trial.

The correct answer is C, C2C, which stands for consumer to consumer. Here both sides of the deal are individuals and the website only provides the listing, the search and sometimes the payment and dispute machinery, earning a fee or advertising revenue rather than a trading margin. Classified and auction platforms such as OLX, Quikr and eBay's classifieds are the standard examples. Option A, B2B or business to business, covers trade between firms, as on IndiaMART or Alibaba, where a manufacturer buys raw material or components. Option B, B2C or business to consumer, is the familiar retail model in which a company sells directly to the shopper, as Amazon and Flipkart do. Option D, G2C or government to citizen, covers public services delivered online, such as railway ticketing through IRCTC or an online passport application. Identify the model by naming the two parties first, then matching the letters.

The correct answer is C, a will. The First Schedule to the Act excludes certain documents from electronic form: a negotiable instrument other than a cheque, a power of attorney, a trust deed, a will or other testamentary disposition, and any contract for the sale or conveyance of immovable property. Option A is wrong because a cheque is specifically carved out of the exclusion of negotiable instruments. Option B is wrong because a contract for the sale of goods may be made electronically, and section 10A expressly confirms the validity of contracts formed by electronic means. Option D is wrong for the same reason; purchase orders and similar commercial communications are exactly the transactions the Act was passed to facilitate. Section 10A, added in 2008, puts the matter beyond doubt by providing that a contract formed through electronic means is not unenforceable merely on that ground.

The correct answer is B, Secure Sockets Layer. 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. Options A, C and D are invented expansions of the kind objective papers use to test whether a candidate has memorised the exact words. A socket in networking is the combination of an IP address and a port number, which is why the protocol that sits above the transport layer and below the application layer was named for sockets. Remember the chain: SSL became TLS, and HTTP protected by either of them is called HTTPS, which runs on port 443.

The correct answer is C, the accelerometer. An accelerometer measures acceleration along three axes, which includes the constant pull of gravity, so the phone can work out which way is down and therefore how it is being held. The system uses that reading to rotate the screen, to count steps and to detect shaking. Option A is wrong because the proximity sensor detects an object close to the top of the screen and blanks the display when the phone is lifted to the ear during a call. Option B is wrong because the ambient light sensor measures the brightness of the surroundings and adjusts screen brightness automatically. Option D is wrong because the magnetometer senses the earth magnetic field and serves as the compass for map applications. A gyroscope refines rotation sensing but the basic orientation switch belongs to the accelerometer.

The correct answer is B, the National Payments Corporation of India. NPCI, set up in 2008 as the umbrella organisation for retail payments in the country, built and runs UPI, which lets a user link several bank accounts to one mobile application and transfer money instantly using a virtual payment address, without sharing account numbers. NPCI also operates RuPay, IMPS, AEPS, the *99# USSD service and the BHIM application released in 2016. Option A, the Reserve Bank of India, is the regulator that authorised and oversees NPCI and the payment systems, but it does not operate UPI itself; the distinction between regulating and operating is the trap in this question. Option C, the State Bank of India, is only one of the member banks on the network. Option D, SEBI, regulates the securities market and has no role in retail payments. Remember the pairing: RBI regulates, NPCI operates.

The correct answer is B, IBM. Herman Hollerith built an electric tabulating machine that read holes punched in cards, and it cut the time needed to process the United States census of 1890 from years to months. He founded the Tabulating Machine Company, which through later mergers and a change of name in 1924 became International Business Machines, that is IBM. Option A is wrong because Intel was founded in 1968 by Robert Noyce and Gordon Moore to make semiconductor memory and then microprocessors. Option C is wrong because Hewlett-Packard was founded in 1939 in a garage in California. Option D is wrong because Microsoft was founded in 1975 by Bill Gates and Paul Allen to write software, not tabulating hardware. The census of 1880 had taken close to eight years to tabulate by hand, and that delay is what prompted his machine.

The correct answer is D, 443. HTTPS is HTTP carried inside an SSL or TLS tunnel, and the port reserved for it is 443, which is why a padlock appears in the address bar when a site is reached on that port with a valid certificate. Option C, port 80, is the default for ordinary unencrypted HTTP, and it is the pair 80 and 443 that examiners test most often. Option A, port 21, belongs to the File Transfer Protocol, which uses 21 for control and 20 for data. Option B, port 25, is the Simple Mail Transfer Protocol used to send electronic mail, with 110 for POP3 and 143 for IMAP on the receiving side. Other numbers worth memorising are 22 for SSH, 23 for Telnet and 53 for DNS. These port numbers are fixed by convention and appear in SSC, Railway and banking papers almost every year.

The correct answer is B, NAND and NOR. Each of these gates alone is enough to build every other gate and so every logic circuit: a NAND with its two inputs tied together acts as a NOT, two NANDs in sequence give an AND, and a suitable arrangement of three gives an OR, and the same can be done entirely with NOR gates. That is why chip makers sell packages containing only one gate type. A is wrong because AND and OR cannot produce a complement by themselves; without a NOT they can never invert a signal. C is wrong because XOR and XNOR are themselves derived gates, built from the basic three, and neither can generate the full set on its own. D is wrong because NOT with AND can indeed build everything, but the pair is not given the name universal gates; the term is reserved for the two single gates that suffice by themselves.

The correct answer is A, commercial transactions carried out through wireless handheld devices. M-commerce, or mobile commerce, is the part of electronic commerce conducted on smartphones, tablets and even feature phones over a wireless network, and the term is credited to Kevin Duffey in 1997. Because the device is personal, portable and location-aware, m-commerce supports mobile banking, mobile ticketing with a QR code, scan-and-pay at a counter, contactless NFC payment, hyperlocal delivery and in-app purchase. Option B describes Electronic Data Interchange, or EDI, the older standard by which firms exchange purchase orders and invoices between their computer systems. Option C is government to government dealing, usually written G2G, which is part of e-governance rather than of mobile commerce. Option D is simply advertising through a mass medium, with no electronic transaction at all, and advertising is only one activity that may support commerce.

The correct answer is C, B2C. Flipkart, Alibaba and Amazon run online marketplaces whose storefronts sell goods to individual shoppers, and a business selling to a consumer is business-to-consumer, or B2C. In this model a firm lists its products on a website or an app, the customer orders and pays online, and the goods reach the home, so the shop, the salesman and the cash counter are all replaced by software. B2C is the commonest face of e-commerce and the one ordinary buyers meet every day. A is wrong because consumer-to-business, C2B, is the reverse case, where an individual offers a service or product to a firm, as a freelance designer or a blogger selling advertising space does. B is wrong because consumer-to-consumer, C2C, means one individual selling to another through a platform such as OLX. D is wrong because business-to-business, B2B, covers a firm selling to another firm, as IndiaMART does. Exam tip: Amazon and Flipkart are B2C, OLX is C2C and IndiaMART is B2B.

The correct answer is B, public key cryptography. RSA, named after Rivest, Shamir and Adleman, works with a linked pair of keys and takes its security from the difficulty of factorising the product of two large prime numbers; it is used both to exchange keys and to create digital signatures. Option A is wrong because symmetric cryptography uses one shared key, and its standard examples are DES, Triple DES and AES. Option C, hashing, is not encryption at all: a hash function such as MD5 or SHA-256 uses no key, produces a fixed-length digest and cannot be reversed, so nothing encrypted by it can be recovered. Option D, steganography, hides the very existence of a message by concealing it inside an image, audio file or document, instead of scrambling its content. A reliable memory aid is that RSA and Diffie-Hellman are asymmetric, while DES and AES are symmetric.

The correct answer is A, SSL or TLS encryption. HTTPS is HTTP carried inside a protected channel: the browser and the server first exchange a digital certificate and agree on keys, after which card numbers, passwords and addresses travel as cipher text that an eavesdropper on the network cannot read. The older protocol was Secure Sockets Layer (SSL) and the current one is Transport Layer Security (TLS), which is why both names appear in textbooks and why the padlock icon is shown in the address bar. Option B, SMTP, is the protocol that carries outgoing e-mail and has nothing to do with web security. Option C, static IP addressing, merely means a device keeps a fixed network address; it does not encrypt anything. Option D, SQL, is the language used to query databases, and a careless implementation of it is itself a security weakness known as SQL injection. For an online payment, HTTPS plus a one-time password is the minimum a shopper should expect.

The correct answer is C, MD5. The Message Digest 5 algorithm takes an input of any length and returns a 128-bit digest. It uses no key, and the process cannot be reversed to recover the input, which is exactly why it is a hash and not a cipher; hashes are used to check that a file or password has not been altered. Options A, B and D are all symmetric block ciphers that encrypt and decrypt with a shared key. AES, chosen in 2001 from the Rijndael design, works on 128-bit blocks with keys of 128, 192 or 256 bits. DES, from the 1970s, used a 56-bit key on 64-bit blocks and is now considered breakable. Blowfish is another block cipher of the same family. The other names in the hash family worth remembering are SHA-1, which gives 160 bits, and SHA-256, which gives 256 bits and is used in blockchains.

The correct answer is B, public procurement of goods and services by government buyers. GeM is an online marketplace on which central and state government departments, public sector undertakings and other public bodies buy common-use goods and services from registered sellers, with the aim of making purchase faster, cheaper and transparent. In the vocabulary of the chapter it is a business-to-government, or B2G, platform, and it also carries features that reserve part of the demand for small enterprises and women-led units. Option A is wrong because income tax returns are filed on the income tax department's own e-filing portal. Option C describes IRCTC, which is a government-to-citizen service for railway ticketing. Option D, company registration, is done through the corporate affairs ministry's MCA portal. Keep GeM distinct from ONDC: GeM is a government buying platform, while ONDC is an open protocol meant to connect buyers and sellers across different private applications.