Convert the hexadecimal number C6 to binary number.

The correct answer is B, Web Resource that specifies its location on a computer network and a mechanism for retrieving it. A URL is the address of a web resource: it says where the resource sits on the network and, through the scheme written in front, how it is to be fetched. Thus it carries the protocol, the host name, the port if one is needed, and the path of the file, and schemes such as http, https, ftp and mailto each bring their own way of retrieving. The idea was given by Tim Berners-Lee along with HTML and HTTP, and a URL is one kind of Uniform Resource Identifier. A is wrong because it is too loose; a URL does not address every computer resource, such as a file on a local disk. C is wrong because a printer is reached through a print queue or an IP address, not by a URL. D is wrong because a storage server is only one of the many things a URL may point to. Exam tip: a URL answers two questions, where the resource is and how to fetch it.

The correct answer is D, http. In a web address the part before the colon and the two slashes names the protocol, so http, the HyperText Transfer Protocol, is the set of rules by which a browser asks a server for a page and the server answers. A full address has four parts: the protocol, the host name, the domain name with its suffix, and the path of the file; in https the letter s stands for secure, because the traffic is encrypted with SSL or TLS. A is wrong because .co marks a commercial entity and is part of the domain name. B is wrong because .in is the country code top level domain for India. C is wrong because www is the host or subdomain name of the web server, not a protocol. Exam tip: read a URL as protocol, then host, then domain, then path, and remember that https is http with SSL or TLS.

The correct answer is C, TCP. The Transmission Control Protocol decides how data is exchanged across the internet and breaks a message into numbered packets that IP then carries to the destination. At the receiving end TCP puts the packets back in order, checks them and asks for any that are missing, which is why it is called a connection-oriented and reliable protocol. It works with IP as the TCP/IP suite, the foundation of the internet, and was designed by Vint Cerf and Robert Kahn. A is wrong because PPP, the Point-to-Point Protocol, only links two nodes directly, as in a dial-up connection. B is wrong because HTTP is an application layer protocol for transferring web pages. D is wrong because SMTP is the application layer protocol that sends email between mail servers. Exam tip: separate the layers - TCP and IP work at the transport and network layers, while HTTP, SMTP and FTP sit at the application layer.

The correct answer is C, HTTP. HTTP, the HyperText Transfer Protocol, is the application-layer protocol a browser uses to ask a web server for a page and to receive the HTML, images and scripts that make it up. It works as a request and response cycle: the browser sends a request such as GET, and the server answers with a status code, 200 for success, 404 when the page is missing and 500 for a server error. HTTPS is the same protocol wrapped in TLS encryption, which is why banking and login pages show a padlock. Option A is wrong because FTP, the File Transfer Protocol, moves files between a client and a server rather than rendering pages. Option B is wrong because SMTP, the Simple Mail Transfer Protocol, is used to send email. Option D is wrong because ARP, the Address Resolution Protocol, maps an IP address to a hardware MAC address inside a local network. Exam tip: HTTP for web pages, FTP for files, SMTP to send mail, POP3 and IMAP to receive it.

The correct answer is D, the input tag with its type attribute set to checkbox. HTML has no separate checkbox element at all. Every simple form control is written with the single input tag, and the type attribute decides what the browser draws, whether that is text, password, radio, checkbox, submit, file or hidden. So a checkbox is made by writing input and setting type to checkbox, while the name and value attributes tell the server which boxes were ticked. Several checkboxes may share one name, which lets a user pick more than one answer; radio buttons that share a name allow only one choice. Option A is wrong because checkbox is written there as a bare word instead of as the value of the type attribute. Option B is wrong because no checkbox element exists in HTML. Option C is wrong because the equals sign is placed straight after the tag name rather than inside a proper attribute. Exam tip: one input tag, many controls, and the type attribute is what changes.