Computer Awareness GK Questions with Answers – Page 20

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.

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 Data Control Language governs who may do what inside the database: GRANT gives a user a privilege such as the right to read or to update a table, and REVOKE withdraws a privilege already given.

MongoDB stores data as documents in a flexible, JSON-like form instead of as rows in tables with a fixed set of columns, and it is queried through its own interface rather than mainly through SQL, which makes it the standard example of a NoSQL database in exam papers.

A table is in second normal form when it is already in first normal form and no non-key attribute depends on only a part of a composite primary key; such a partial dependency is removed by moving that attribute into a table of its own.

The degree of a relation counts its attributes, that is its columns, so a student table holding roll number, name, class and marks has degree four whatever the number of students in it.

Isolation means that transactions running at the same time do not see one another's incomplete work, so two clerks booking the last seat cannot both succeed; the database behaves as though the transactions ran one after the other.

A foreign key is the column that stores values belonging to the primary key of another table, so a marks table can carry the roll number of a student table and the two tables can then be joined; the database uses it to enforce referential integrity, refusing a value that…

The designer picks one candidate key as the primary key of a table, and the database then enforces two rules on it: its value must be different in every row, and it can never be left null, since a missing value would make a row impossible to identify.

TRUNCATE empties a table in one operation, leaving the columns, data types and constraints in place so that the table can be filled again at once; because it changes the object rather than selected rows it is grouped with the Data Definition Language and it is much faster than deleting…

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.

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.

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.

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 is the helpline on which a victim of online financial fraud should call at once, because a report made within the first hours lets banks and payment operators freeze the money before it is withdrawn; complaints can also be filed on the national cybercrime reporting portal.

Anyone may hold the public key and use it to encrypt a message, but only the holder of the matching private key can decrypt it, so no secret has to be exchanged in advance; RSA is the standard example, and the same pair used the other way round produces a…

The name counts the days the software maker has had to fix the flaw, and that number is zero: the attacker knows of a weakness that the vendor has not discovered or not yet repaired, so no update protects the user and even a fully patched system is exposed.

CAPTCHA stands for Completely Automated Public Turing test to tell Computers and Humans Apart, and it is the distorted text, image grid or check box that a site shows before accepting a form, so that automated programs cannot register accounts, book tickets in bulk or guess passwords by the thousand.

The correct answer is B, CERT-In, the Indian Computer Emergency Response Team, which works under the Ministry of Electronics and Information Technology and is the national agency for collecting, analysing and issuing alerts on cyber incidents and for coordinating the response to them.

It locks the files by encrypting them and shows a demand for money, usually in a crypto currency, in exchange for the key; the WannaCry outbreak of 2017 struck hospitals, factories and offices in many countries and is the example examiners quote.