Computer Internet Questions and Answers

Answer: B

z-index controls the stacking order of elements.

Where positioned elements (position relative, absolute, fixed or sticky) overlap, z-index decides which appears in front. A higher value is stacked above a lower one within the same stacking context, which is how modals and drop-down menus are kept on top.

Font size is set by font-size and transparency by opacity. Zoom level is a browser setting, or the scale transform, not z-index.

Answer: C

The method is PUT.

PUT replaces the resource at the given URI with the representation sent. Sending the same PUT once or ten times leaves the resource in the same state, so it is idempotent by definition in the HTTP specification (RFC 9110). It is the standard method for updating a resource.

POST is not idempotent, since repeating it may create duplicates. GET is idempotent but only reads and never updates. PATCH applies a partial change and is not guaranteed to be idempotent, for example a patch meaning 'add 1 to the counter'.

Answer: B

The purpose of AJAX is asynchronous communication with the server.

AJAX (Asynchronous JavaScript and XML) lets a web page send requests and receive data in the background, through XMLHttpRequest or fetch, and update part of the page without reloading it. Live search suggestions and infinite scrolling feeds work this way. The data is now usually JSON rather than XML.

Server-side validation runs on the server. Database management is the job of a DBMS. Styling is done with CSS. AJAX is about how the browser talks to the server.

Answer: C

A cookie's primary purpose is to store small amounts of data on the client side.

A cookie is a small name-value pair, limited to about 4 KB, that the server sets through the Set-Cookie header and the browser sends back with later requests. Because HTTP is stateless, cookies are used to keep session identifiers, preferences and tracking state.

Large amounts of client data go in localStorage or IndexedDB, not cookies. Cookies do not execute any script. Encryption of data in transit is the job of TLS.

Answer: B

A closure is a function bundled with its lexical environment.

When a function is defined inside another function, it keeps access to the outer function's variables even after the outer function has returned. For example, function counter() { let c = 0; return () => ++c; } returns a function that remembers and updates its own c. Closures are used for data privacy, callbacks and function factories.

A function that returns nothing simply returns undefined. Loop termination conditions and error handling (try/catch) are unrelated.

Answer: B

DOM stands for Document Object Model.

The DOM is the W3C/WHATWG standard interface that represents an HTML or XML document as a tree of nodes. Scripts can read and change it, for example with document.getElementById, which is how JavaScript updates the content and structure of a page dynamically.

Data Object Model, Dynamic Output Method and Digital Operation Management are invented expansions that reuse plausible words with the same initials.

Answer: D

The action not supported by pure HTML is Display the client time as part of the page.

Showing the visitor's current time needs code that runs in the browser, such as JavaScript, to read the clock. HTML alone only describes static content.

The other actions are possible without scripting: an iframe or img tag embeds objects from other sites, and a meta http-equiv="refresh" tag can reload the page after an interval or redirect to another page.

Answer: D

ActiveX controls can be embedded in Web pages.

ActiveX controls are compiled binary components, Microsoft's technology for adding interactive features to web pages viewed in Internet Explorer, where they run as native code on the user's machine. This is also why they posed security risks.

'URL pages' and 'script pages' are not types of document, and while ActiveX controls could be used in some Office documents, the standard description is web pages.

Answer: B

The <map> tag defines clickable regions in an image.

The map element holds area elements, each giving a shape and coordinates and a link. Linked to an img through its usemap attribute, it creates an image map in which different parts of the picture lead to different pages.

It does not draw paths, highlight areas, or describe the site map of a website, which is a separate page or XML file.

Answer: A

The answer is P only.

Statement P is true: JavaScript is dynamically typed, so a variable can hold a number at one moment and a string the next; the type belongs to the value, not to the variable.

Statement Q is false: images can be shown without the img tag, for example as CSS background images, through the picture or object elements, or drawn with canvas or SVG. So 'Q only', 'Both' and 'Neither' are wrong.