Computer Awareness Mixed Quiz: Set 16

The correct answer is B, 9. In the binary system every place stands for a power of two, and 257 is 256 plus 1, that is two raised to the eighth plus two raised to the zero. It is therefore written as 100000001, a one followed by seven zeros and another one, which is nine digits in all. A quicker way is to look for the largest power of two that fits inside the number: for 257 that is 256, so the highest place used is the ninth from the right, and every number from 256 up to 511 needs exactly nine binary digits. A is wrong because eight digits reach only up to 255, one short of 257. C is wrong because seven digits stop at 127. D is wrong because ten digits become necessary only from 512 onward. Exam tip: n binary digits count from 0 to two raised to n minus one, so 8 bits end at 255.

The correct answer is B, Datasheet. In a database such as Microsoft Access, the view that shows a table as rows and columns, looking like a spreadsheet grid, is called Datasheet view. Each row of that grid is one record and each column is one field, and the names along the top come from the field names set in Design view. Datasheet view lets you type data straight in, sort it, filter it and widen columns, while Design view is where the data type, field size and primary key are fixed. Queries and forms can also be opened in Datasheet view, so the name belongs to the display format, not to one object. Option A is wrong because a record is a single row of the grid, one complete entry, not the grid itself. Option C is wrong because a query is a saved question that pulls out selected rows; it is a database object. Option D is wrong because 'Tables' names the objects being displayed, while the question asks what the grid-like view is called. Exam tip: Access tables have two main views — Datasheet for data, Design for structure.

The correct answer is A, phishing attack. Phishing sends a message that looks as if it came from a bank, an employer or a government office, and asks the reader to confirm a password, a card number or a one-time password on a page that belongs to the attacker; the target of the attack is the person, not the machine, which is why it is classed as social engineering. Option B is wrong because SQL injection puts database commands into a web form to make the server reveal stored data; the user is not tricked at all. Option C is wrong because a denial of service attack floods a server with requests so that genuine users cannot reach it, which harms availability and steals nothing. Option D is wrong because option A is correct. Remember the family: spear phishing on one person, whaling on an executive, vishing by call, smishing by message.

The correct answer is C, Netscape. Netscape Navigator, released in 1994 by Netscape Communications, the company founded by Marc Andreessen and Jim Clark, was the first web browser sold as a commercial product. It was the browser that carried the web to ordinary users in the mid nineties and at its peak held most of the market, before losing the browser war to Internet Explorer. A is wrong because Mosaic, built in 1993 at the NCSA of the University of Illinois, was the first widely used graphical browser but was academic software given away free, not a commercial product. B is wrong because Mozilla is the open source project born in 1998 from Netscape's released source code; its browser Firefox came in 2004 and is free. D is wrong because Internet Explorer arrived in 1995 and was bundled free with Windows rather than sold. Exam tip: Mosaic 1993 first popular graphical browser, Netscape Navigator 1994 first commercial browser, Firefox 2004 from the Mozilla project.

The correct answer is A, hierarchical. The hierarchical model is the first data model used in commercial database software; IBM built its Information Management System on it in the 1960s for the Apollo programme. It arranges records as a tree in which every child record has exactly one parent, so data is reached by moving down a path from the root. Option B is wrong because the object oriented model, which stores objects together with their methods, is the newest of the four and belongs to the late 1980s. Option C is wrong because the deductive model, which adds logical rules to stored facts, came even later and remains mostly a research model. Option D is wrong because the relational model was proposed by Edgar Frank Codd in 1970, after the hierarchical and network models were already in use, though it later replaced both in practice.

The correct answer is C, Graphics. In multimedia, graphics is the broad word for every kind of visual element a computer can store and show, so drawings, photographs, movies and simulations all sit inside it. The usual list of multimedia elements is text, graphics, audio, video and animation, and in that list graphics covers both pictures made by hand on the screen and pictures captured from the real world. Graphics are stored either as bitmaps, made of pixels, as in a JPEG or BMP photograph, or as vectors, made of lines and curves described by equations, as in a drawing or a CAD file. A is wrong because animation is only one kind of visual, a sequence of frames shown fast enough to look like movement. B is wrong because an image is a single still picture, so it is narrower than the four things listed. D is wrong because text is made of characters and carries no picture. Exam tip: multimedia elements are text, graphics, audio, video and animation; bitmap graphics use pixels, vector graphics use equations.

The correct answer is B, Meta Search Engine. A meta search engine keeps no index of its own. It hands the user's query to several other search engines at the same time, collects what they send back, removes repeated hits and shows one merged list. Because it borrows from many sources, a single search covers more of the web than any one engine would on its own. Dogpile and Startpage work in this way. A is wrong because advanced search only means the extra filters an ordinary engine offers, such as date, file type or exact phrase, while it still searches its own index. C is wrong because search tool is a loose term for any utility that finds files or text, not a defined class of engine. D is wrong because Boolean searching refers to using AND, OR and NOT inside one engine, not to querying other engines. Exam tip: meta means about, so a meta search engine searches the searchers.

The correct answer is A, REL. An external stylesheet is attached to a page with a link tag written inside the head section, and the tag needs two things: href, which gives the address of the CSS file, and rel, which tells the browser what the linked file is for. Writing rel equals stylesheet is what marks the file as a set of style rules; leave rel out and the browser has no reason to treat the file as CSS, so the page appears unstyled. B is wrong because style is a separate way of writing CSS, either as a style block in the head or as an attribute on one element, and it has no part in linking an external file. C is wrong because body holds the visible content of the page while the link tag belongs in the head. D is wrong because html is the root element that wraps the whole document and has nothing to do with loading a stylesheet. Exam tip: link rel equals stylesheet with href, placed in the head.

The correct answer is A, HREF. The href attribute of the anchor tag carries the address the browser should open when the link is clicked, so href alone decides where a link leads. The text written between the opening and closing anchor tags is what the reader sees and clicks. The value of href can be a full web address, a path to another file on the same site, or a point inside the same page written after a hash. B is wrong because src supplies the source file for images, scripts and iframes, not for links. C is wrong because link is a separate element placed in the head section to attach stylesheets; it is not an attribute of the anchor tag. D is wrong because HYPERLINK is not an HTML attribute at all, it is the name of a spreadsheet function. Exam tip: remember the pair — href points a link somewhere, src pulls a file in.

The correct answer is A, B2C (Business to Consumer). In the business to consumer model a firm sells goods or services directly to the person who will use them, and Amazon's retail store is the best known example: a shopper opens the site or the app, puts an item in the cart and buys it, with no wholesaler or trader in between. Every e-commerce model is named in the same way, by who stands at each end of the deal, so learning the four pairs is enough to answer most questions on this topic. B is wrong because business to business means one firm selling to another, the way a parts maker supplies a car factory or IndiaMART links wholesalers. C is wrong because consumer to business is the reverse, where an individual offers a service to a company, as a freelance designer does on a bidding site. D is wrong because consumer to consumer is one individual selling to another, as on OLX or Quikr. Exam tip: B2C is Amazon retail, B2B is IndiaMART, C2C is OLX and C2B is freelancing sites.

The correct answer is B, to block unauthorised access to a network. A firewall sits between a trusted internal network and the untrusted world outside, inspects the traffic crossing it and permits only what its rules allow, dropping the rest; it may be a hardware appliance, a software program or both together. Option A is wrong because unrestricted access is the exact opposite of what a firewall exists to provide, and a network left open in that way needs no firewall at all. Option C is wrong because taking backups is the work of backup software and storage policy; a firewall keeps no copy of data and would not help after a disk failure. Option D is wrong because option B states the purpose correctly. Note the common types for objective questions: packet filtering, stateful inspection and the proxy or application gateway firewall.

The correct answer is A, Program counter. In the 8085A microprocessor the program counter is a 16-bit register that always holds the memory address of the next instruction, or op-code, to be fetched. After each fetch it is incremented automatically, and a jump or call instruction loads a new address into it so that control moves elsewhere in the program. Two other registers of the 8085 are often confused with it. The accumulator is the 8-bit register A in which arithmetic and logic results are stored. The stack pointer is a 16-bit register holding the address of the top of the stack, used while saving return addresses and register contents. B and C are wrong for those reasons. D is wrong because instruction pointer is the name Intel's later x86 processors use for the same idea; the 8085 register is called the program counter. Exam tip: 8085 has an 8-bit accumulator and 16-bit program counter and stack pointer.

The correct answer is B, Edgar Frank Codd. Codd, a British computer scientist working at IBM, set out the relational model in a paper published in 1970, proposing that all data be held in simple two-dimensional tables and joined by matching values rather than by fixed pointers. Every relational database, from Oracle to MySQL, rests on that idea, and he is therefore called the father of the relational database. Option A is wrong because Charles Babbage designed the Difference Engine and the Analytical Engine in the nineteenth century and is called the father of the computer. Option C is wrong because Dennis Ritchie developed the C language and, with Ken Thompson, the Unix operating system. Option D is wrong because James Gosling created the Java programming language at Sun Microsystems, which has nothing to do with the relational model.

The correct answer is B, Half-duplex. Data can travel between two devices in three modes. In half-duplex mode both devices can send and receive, but only one of them may transmit at any given moment, so the traffic takes turns; a walkie-talkie is the standard example, and older hubs and CB radio worked the same way. In simplex mode data moves in one direction only, as from a keyboard to the computer or from a radio station to a receiver. In full-duplex mode both sides can send and receive at the same time, as in a telephone call or on a modern switched network. A is wrong because simplex allows no return traffic at all. C is wrong because three-quarters duplex is not a recognised mode. D is wrong because only one of the listed modes fits the description. Exam tip: simplex is one way, half-duplex is both ways by turns, full-duplex is both ways together.

The correct answer is B, botnet attack. A botnet is built by infecting many connected devices, each of which becomes a zombie obeying a single controller; the network so assembled is then rented out or used for spam, fraud or a flood of traffic. The wording of the question, many interconnected devices turned into one attack network, describes the building of the botnet itself. Option A is wrong for a reason worth understanding: a distributed denial of service attack is usually launched from a botnet, but it names the flooding of one victim, not the assembling of the device network. Option C is wrong because a zero-day attack exploits a flaw the vendor does not yet know of and has nothing to do with numbers of devices. Option D is wrong because spear phishing is a targeted fraudulent message sent to one chosen person.

The correct answer is D, the operating system will return an error indicating that the directory is not empty. The plain remove-directory command is built to delete an empty folder only. In Windows it is rmdir, also written rd, and in Linux it is rmdir; both stop with a message such as "The directory is not empty" when anything is still inside. To remove a folder along with everything in it you have to ask for it: rmdir /s in Windows or rm -r in Linux, which walks through the tree, deletes the contents and then the folder. This guard exists so that a single short command cannot wipe out a large tree by mistake. Option A is wrong because nothing inside is touched without the recursive switch. Option B is wrong because a file system cannot leave files with no parent folder; the entries go together or not at all. Option C is wrong because the plain command does not ask item by item, which is what an interactive option like rm -i does. Exam tip: rmdir empties only, rm -r for the whole tree.

The correct answer is C, tuple. In the vocabulary of the relational model a table is a relation, and one complete horizontal entry of that table, such as all the details of a single student, is a tuple; the ordinary words for it are row and record. Option A is wrong because an attribute is a column of the table, that is one property such as roll number or date of birth, and is counted by the degree of the relation. Option B is wrong because a domain is the set of values an attribute is allowed to take, for example the whole numbers one to one hundred for a marks column. Option D is wrong because the relation is the entire table, not one of its rows. Keep the pairing firm: relation is the table, tuple the row, attribute the column, and cardinality counts the tuples.

The correct answer is D, all of the above, because cyber security is not one activity but a programme that covers all three. Option A by itself is incomplete: compliance means following the rules, standards and laws that apply to the data an organisation holds, and it is only one strand of the work. Option B by itself is incomplete as well: defence against internal threats guards against the employee who misuses access or leaks data, a large share of real incidents, but an organisation that watched only its insiders would still fall to an outside attack. Option C by itself is incomplete too: threat prevention covers firewalls, antivirus, patching and monitoring that stop an attack before it lands. Since each of the three is a genuine part of cyber security and none of them alone is the whole, the combined option is the answer.

The correct answer is B, CREATE. The Data Definition Language deals with the structure of the database rather than with the data inside it, and CREATE is its basic command, used to build a table, a view or the database itself; ALTER, DROP, TRUNCATE and RENAME belong to the same group. Option A is wrong because INSERT adds new rows to an existing table and is therefore a Data Manipulation Language command. Option C is wrong because SELECT reads rows and returns a result set, which is again manipulation of data, not definition of structure; some books place it in a separate Data Query Language. Option D is wrong because UPDATE changes values already stored in rows and is also DML. Remember the split by what changes: structure means DDL, contents mean DML, rights mean DCL with GRANT and REVOKE.

The correct answer is B, integrity. The triad names the three goals of information security: confidentiality, that only authorised people can read the data; integrity, that the data is complete and unaltered from the moment it was created or sent; and availability, that the system works when an authorised user needs it. Option A is wrong because identification, along with authentication, is a means of achieving these goals rather than one of the three goals themselves. Option C is wrong because the internet is the medium over which most attacks travel and is no part of the model. Option D is wrong because isolation, such as keeping a critical machine off the network, is one technique among many for protecting a system. A useful way to recall the triad is to ask who may read the data, whether it can be changed, and whether it can be reached.