Internet, Networking & Security MCQs With Answers
Networking and the internet now feature in every computer science syllabus, along with the threats that come with them. These internet, networking and cyber security MCQs cover LAN, WAN and VLAN, network topologies, the OSI model, routers, switches, hubs, bridges, modems and gateways, IP and MAC addresses, IPv4 and IPv6, subnet masks, protocols such as HTTP, HTTPS, DNS, DHCP, SMTP, IMAP and SFTP, Wi-Fi and Bluetooth, the web, browsers, search engines, cookies and cloud computing, and security topics including malware, viruses, worms, trojans, ransomware, phishing, firewalls, encryption, VPNs and two-factor authentication. They suit PPSC, FPSC, NTS and IT job tests.
Take a scored quiz instead →In the OSI reference model, which layer is responsible for logical (IP) addressing and for routing packets from the source host to the destination host?
The Network Layer (Layer 3) handles logical IP addressing, routing of packets across interconnected networks, and path selection. Data Link handles physical MAC addresses, while Transport manages end-to-end process identification via port numbers.
Which network protocol automatically assigns IP addresses, subnet masks, and default gateways to devices on a network?
DHCP (Dynamic Host Configuration Protocol) automatically leases IP configuration settings to network clients. DNS resolves domain names to IP addresses, and FTP is used for file transfers.
What default port number is used by the secure HTTP protocol (HTTPS) encrypted via SSL/TLS?
HTTPS uses TCP Port 443. Standard HTTP operates on Port 80, FTP uses Port 21, and SMTP (for sending email) operates on Port 25.
Which IP address range represents the standard Class C private IPv4 address space defined by RFC 1918?
RFC 1918 defines Private IPv4 spaces: Class A is 10.0.0.0/8, Class B is 172.16.0.0/12, and Class C is 192.168.0.0/16. The 127.0.0.0/8 range is reserved for loopback testing.
What topology connects every network device to a central hub or switch using individual cables?
In Star Topology, all host nodes are connected directly to a central device (switch or hub). If one link fails, only that node is disconnected, unlike Bus topology where a trunk break drops the whole network.
What type of malware tricks users into downloading or executing it by disguising itself as legitimate, harmless software?
A Trojan Horse masks itself as legitimate software to trick users into running it. Unlike worms, Trojans do not self-replicate automatically; they rely on user action or social engineering.
In cryptography, what type of encryption utilizes two distinct keys—a Public Key for encryption and a Private Key for decryption?
Asymmetric Cryptography (Public Key Cryptography, like RSA) uses a mathematically linked pair of public/private keys. Symmetric encryption uses a single shared secret key for both operations.
Which security measure monitors incoming and outgoing network traffic based on predefined security rules to block unauthorized access?
A Firewall acts as a barrier between secure internal networks and untrusted external networks (like the Internet), packet-filtering based on IP, port, and security policies.
Which cryptographic hash algorithm produces a fixed 256-bit (32-byte) digest output and is widely used in Bitcoin and TLS standard security?
SHA-256 (Secure Hash Algorithm 256-bit) belongs to the SHA-2 family. It creates a one-way fixed output used in digital signatures, SSL/TLS certificates, and blockchain networks. MD5 and SHA-1 are cryptographically broken.
Which cloud computing service delivery model provides virtualized computing resources (like virtual machines, storage, and networking) over the internet?
IaaS (e.g., AWS EC2, Azure VMs) provides raw virtualized hardware infrastructure. PaaS provides a managed application environment (e.g., Heroku), and SaaS offers fully hosted user applications (e.g., Google Workspace).
What distributed, decentralized digital ledger technology securely records transactions across a peer-to-peer network using cryptographic hashing?
Blockchain is an immutable, append-only distributed ledger where blocks of transaction data are linked sequentially using cryptographic hashes, eliminating central authorities.
Which networking device operates at the Data Link Layer (Layer 2) of the OSI model and uses MAC addresses to forward frames to specific target ports?
A Network Switch works at Layer 2 (Data Link) and uses a MAC address table to forward frames selectively. A Hub works at Layer 1 (Physical) and broadcasts traffic to all ports. A Router operates at Layer 3 (Network).
What metric measures the maximum theoretical data transfer capacity of a network communication channel over a given period?
Bandwidth is the maximum theoretical capacity of a channel (e.g., 100 Mbps). Throughput is the actual speed of successful data delivery achieved in practice. Latency is delay, and Jitter is latency variation.
Which standard protocol is used to securely transfer files over an SSH connection between a client and a remote server?
SFTP (SSH File Transfer Protocol) encrypts both commands and data payloads over TCP port 22. Standard FTP sends credentials in plain text, making it vulnerable to packet sniffing.
Which security attack involves overwhelming a target web server with a flood of malicious traffic from multiple compromised distributed computers (botnet)?
A DDoS attack uses a network of infected botnet devices to saturate bandwidth and system resources of a target site, making it unavailable to legitimate users.
Which vulnerability allows an attacker to manipulate backend SQL database queries by inputting untrusted payload text into input fields?
SQL Injection occurs when unvalidated user input is directly concatenated into SQL queries. Prepared Statements (Parameterized Queries) are the primary defense against SQLi.
Which wireless communication protocol standard defines Low-Rate Wireless Personal Area Networks (LR-WPANs) widely used in IoT smart home sensors?
IEEE 802.15.4 forms the physical and MAC layers for high-efficiency, low-power networks like Zigbee. IEEE 802.11 defines Wi-Fi, IEEE 802.3 defines Ethernet, and IEEE 802.16 defines WiMAX.
What is the standard subnet mask assigned to a Class B IPv4 network by default?
Class A default subnet mask is 255.0.0.0 (/8), Class B default is 255.255.0.0 (/16), and Class C default is 255.255.255.0 (/24).
What does ‘HTTP’ stand for in website web addresses?
HTTP stands for Hypertext Transfer Protocol. It is the foundational protocol used by the World Wide Web to transmit and request data between web browsers and web servers.
Which network protocol is specifically used for transmitting electronic mail (email) messages between servers?
SMTP (Simple Mail Transfer Protocol) is an internet standard communication protocol used specifically for sending outgoing email messages across IP networks.
What field in an email client is used to send a copy of an email to someone without revealing their email address to other recipients?
Bcc stands for Blind Carbon Copy. Addresses placed in the Bcc field receive a copy of the message, but their email addresses remain completely hidden from all other recipients in the To and Cc fields.
What is the unique numerical label assigned to every device connected to a computer network that uses the Internet Protocol for communication?
An IP Address (Internet Protocol Address) is a unique numerical identifier assigned to every device connected to a computer network, allowing devices to locate and communicate with each other.
Which software application is used to access, view, and navigate web pages on the Internet?
A Web Browser (such as Google Chrome, Mozilla Firefox, Microsoft Edge, or Safari) is application software used to fetch, translate HTML/CSS, and display web pages from web servers.
What does ‘URL’ stand for in web navigation?
URL stands for Uniform Resource Locator. It is the specific web address used to identify and locate a unique resource (like a web page, image, or document) on the World Wide Web.
What fraudulent practice involves sending fake emails pretending to be from reputable companies to steal personal information like passwords and credit card numbers?
Phishing is a social engineering attack in which fake emails or messages, made to look as if they come from trusted organisations, trick people into giving away passwords or card details.
Pharming redirects users to a fake website by tampering with DNS, and spoofing means forging the sender of a message.
What software is designed specifically to detect, prevent, and remove malicious software from a computer system?
Antivirus software is a security program created to scan files and memory for known virus signatures, heuristic anomalies, and malware, isolating or deleting infected files.
What does the ‘S’ stand for in HTTPS?
The 'S' in HTTPS stands for 'Secure'. HTTPS encrypts standard HTTP communication using Transport Layer Security (TLS) or Secure Sockets Layer (SSL) protocols, protecting data against eavesdropping and tampering (default port 443).
Which network system translates human-readable domain names (like www.google.com) into numerical IP addresses?
DNS (Domain Name System) functions as the 'phonebook of the Internet'. It translates human-friendly domain names (e.g., google.com) into machine-readable IP addresses (e.g., 142.250.190.46) so browsers can locate web resources (operates on port 53).
Which protocol is designed for retrieving emails from a mail server while leaving a copy on the server?
IMAP (Internet Message Access Protocol) retrieves emails from mail servers while maintaining synchronization across multiple devices. Unlike POP3 (which downloads and removes emails from the server), IMAP keeps emails on the server (default port 993 for IMAPS).
What is the full form of IP in computer networking?
IP stands for Internet Protocol. It is the principal set of rules governing packet formatting and addressing to route data across network boundaries and deliver packets from source hosts to destination hosts over the Internet.
An IPv4 address consists of how many bits?
An IPv4 (Internet Protocol Version 4) address consists of 32 bits divided into 4 octets (bytes) separated by dots (e.g., 192.168.1.1). It allows for approximately 4.3 billion unique global addresses (2³²).
An IPv6 address consists of how many bits?
An IPv6 (Internet Protocol Version 6) address consists of 128 bits expressed as eight groups of four hexadecimal digits separated by colons (e.g., 2001:0db8:85a3::8a2e:0370:7334). It was created to replace IPv4, providing 2¹²⁸ (over 3.4 × 10³⁸) unique addresses.
What is a unique physical address assigned to a Network Interface Card (NIC) by its manufacturer called?
A MAC (Media Access Control) address is a unique 48-bit hardware identifier assigned to a Network Interface Card (NIC) during manufacturing. It operates at Layer 2 (Data Link Layer) of the OSI model, unlike IP addresses which operate at Layer 3.
How long is a standard MAC address in bits?
A standard MAC address is 48 bits long (6 bytes), typically written in hexadecimal format as six pairs of characters separated by colons or hyphens (e.g., 00:1A:2B:3C:4D:5E). The first half identifies the vendor (OUI), and the second half is the device serial.
What is a malicious software program designed to replicate itself and spread to other computers called?
A computer virus or worm is malicious software designed to replicate itself. Viruses require host files and user action to spread, whereas worms self-replicate independently over computer networks without needing human intervention or host programs.
What type of malware restricts access to a computer system or files and demands payment to restore access?
Ransomware is a category of cyber extortion malware that encrypts files on a target victim's machine using strong cryptography (such as AES-256). The attacker demands a payment (usually in cryptocurrency like Bitcoin) in exchange for the decryption key.
Which wireless technology uses short-wavelength UHF radio waves for short-range data exchange between devices (2.4 GHz)?
Bluetooth is a short-range wireless communication standard operating on UHF radio waves in the 2.4 GHz ISM band (2.402 to 2.480 GHz). Invented by Ericsson in 1994, it enables local data exchange between mobile devices, headphones, and peripherals within ~10 to 100 meters.
What does Wi-Fi stand for?
Wi-Fi is the trade name, set by the Wi-Fi Alliance, for wireless networking based on the IEEE 802.11 standards, using the 2.4, 5 and 6 GHz bands. In exams it is commonly expanded as 'Wireless Fidelity', although the Alliance says the name is not officially an abbreviation.
Google Workspace and Microsoft 365 are examples of which cloud computing service model?
SaaS (Software as a Service) delivers complete, cloud-hosted software applications to end-users directly over a web browser, eliminating local installation and maintenance. Examples include Google Workspace (Gmail, Docs), Microsoft 365, Salesforce, and Dropbox.
What is the full form of LAN?
- LAN stands for Local Area Network.
- It connects computers within a small area like an office.
- LANs are usually faster than wider networks.
What is the full form of WAN?
- WAN stands for Wide Area Network.
- It connects computers over large areas, like across cities.
- The internet is the largest example of a WAN.
Which powerful computer is used to provide services or data to many other computers on a network?
- A server provides data or services to many other computers.
- It is usually more powerful than a personal computer.
- Websites are commonly hosted on servers.
Which port is commonly used to connect a computer directly to a wired network?
- The Ethernet port connects a computer to a wired network.
- It uses a cable with an RJ45 connector.
- Wired connections are often more stable than Wi-Fi.
What is the short-range wireless technology used to connect wireless earphones to a phone called?
- Bluetooth connects devices like wireless earphones over short distances.
- It does not need cables to work.
- Its range is usually shorter than Wi-Fi.
What is the wireless technology called that lets a computer connect to the internet without cables?
- Wi-Fi lets a computer connect to a network wirelessly.
- It uses radio waves instead of cables.
- Most homes use Wi-Fi for internet access.
A computer network is best described as what?
- A computer network is a group of connected computers.
- They share data and resources with each other.
- Networks can be small, like a home, or very large, like the internet.
Which term describes connecting a computer to power and other devices using cables?
- A wired connection uses physical cables to connect devices.
- It is often more stable than a wireless connection.
- Ethernet cables are a common example of a wired connection.
What is the term for a computer that a company or user rents remotely to store data or run websites?
- A cloud server is a remote computer used to store data or run websites.
- Users access it over the internet.
- Cloud servers remove the need to own physical server hardware.
What is the term for storing files online so they can be accessed from different devices?
- Cloud storage means saving files on remote servers.
- Files can be accessed from any device with internet access.
- It is different from storing files only on a local hard disk.
What do we call everyday devices, such as smart watches, that connect to the internet and share data?
- The Internet of Things connects everyday devices to the internet.
- Smart watches and smart thermostats are common examples.
- These devices can collect and share data automatically.
What is the general term for a computer’s ability to work without an active internet connection?
- Offline mode lets a program work without internet access.
- Some features may be limited while offline.
- Many apps sync data again once reconnected to the internet.
Which term describes a computer network limited to devices within a single home or office?
- A Local Area Network (LAN) covers a small area like a home or office.
- It connects nearby devices together.
- LANs are usually faster than larger networks.
What is the term for a program used to send and receive email?
- An email client is used to send and receive email.
- Microsoft Outlook is a common example.
- Email clients also organize messages into folders.
What is a program used to find information on the internet using keywords called?
- A search engine helps find information using keywords.
- Google and Bing are common examples.
- It ranks results based on relevance.
What is the address used to find a specific webpage on the internet called?
- A URL is the address used to find a webpage.
- Every webpage has its own unique URL.
- It usually begins with http:// or https://.
What is the readable address of a website, such as ‘example.com’, called?
- A domain name is a website's easy-to-remember address.
- It replaces a numeric IP address.
- Examples include .com, .org, and .pk.
What is the term for a company that provides internet access to homes and businesses?
- An Internet Service Provider (ISP) gives access to the internet.
- Customers usually pay a monthly fee.
- Broadband and fiber are common types of connections.
What is software designed to damage or disrupt a computer called?
- Malware is software designed to damage a computer.
- It includes viruses, worms, and ransomware.
- Antivirus software helps detect and remove malware.
What is a small text file a website saves on your computer to remember login details called?
- A cookie is a small file websites use to remember information.
- It can store login status or preferences.
- Users can manage cookies in browser settings.
What is stored data that helps a webpage load faster on a return visit called?
- Cache stores temporary data to help pages load faster.
- Web browsers use it to avoid re-downloading content.
- Clearing cache can sometimes fix loading issues.
What is unwanted, repetitive advertising email called?
- Spam is unwanted, repetitive bulk email.
- It is often used for advertising or scams.
- Email services use filters to block spam automatically.
What is the process of converting data into a secret code to protect it called?
- Encryption converts data into a coded format.
- Only someone with the correct key can read it.
- It protects sensitive data like passwords and payments.
What is buying and selling goods or services over the internet called?
- E-commerce means buying and selling goods online.
- Online stores are a common example.
- It relies on secure payment systems.
What is a private, work-only network used inside a company, based on internet technology, called?
- An intranet is a private network used within an organization.
- It uses internet-based technology but is restricted to employees.
- It is used for internal communication and shared files.
What is the computer or device that requests information from a server called?
- A client requests information from a server.
- A web browser acts as a client requesting webpages.
- The server then responds with the requested data.
What is a device that converts digital signals for internet access over phone or cable lines called?
- A modem converts digital data for internet transmission.
- It also converts incoming signals back to digital data.
- Many homes use a combined modem-router device.
What is a device that connects multiple devices in a network and directs data traffic called?
- A router connects devices in a network and directs data.
- It also connects a home network to the internet.
- Many routers also provide Wi-Fi access.
What security process requires two separate steps, like a password and a phone code, to log in?
- Two-Factor Authentication (2FA) needs two steps to log in.
- It adds extra security beyond just a password.
- A common second step is a code sent to a phone.
What is a secure, encrypted connection used to protect privacy on the internet called?
- A VPN creates a secure, encrypted internet connection.
- It helps protect privacy while browsing.
- VPNs are also used to access company networks remotely.
What is a test used on websites to check whether the user is a human and not a bot called?
- CAPTCHA checks whether a website visitor is human.
- It often asks users to identify images or type text.
- It helps prevent spam and fake accounts.
What is the practice of gaining unauthorized access to a computer system called?
- Hacking means gaining unauthorized access to a system.
- It can be malicious or, sometimes, legitimate security testing.
- Unauthorized hacking is illegal in most countries.
What software helps a website’s owner create and publish content without coding?
- A Content Management System (CMS) helps create website content.
- It does not require deep coding knowledge.
- WordPress is a common example of a CMS.
What is a website design that adjusts to look good on phones, tablets, and desktops called?
- Responsive design adjusts a website's layout for different screens.
- It works well on phones, tablets, and desktops.
- It gives users a consistent experience on any device.
What is the process of improving a website so it ranks higher in search results called?
- SEO stands for Search Engine Optimization.
- It improves a website's ranking in search results.
- Good content and keywords help improve SEO.
What is a regularly updated website featuring articles, often written informally, called?
- A blog is a regularly updated website with articles.
- Posts usually appear newest first.
- Blogs can cover almost any topic.
What is a collaborative website that many users can edit together, like Wikipedia, called?
- A wiki is a website that many users can edit together.
- Wikipedia is a well-known example.
- Wikis are often used for shared knowledge bases.
What is a series of downloadable or streamed audio episodes on a topic called?
- A podcast is a series of audio episodes on a topic.
- Users can subscribe and listen through an app.
- Podcasts cover a wide range of subjects.
What is a digital version of a printed book, readable on a tablet or e-reader, called?
- An e-book is a digital version of a printed book.
- It can be read on a tablet, phone, or e-reader.
- E-books are portable and take up no physical shelf space.
What is a square-shaped code that can be scanned by a phone to open a link called?
- A QR code is a square-shaped scannable code.
- Phones can scan it to quickly open a website or info.
- QR codes can store more data than a regular barcode.
What is the satellite-based system used to find a device’s exact location called?
- GPS stands for Global Positioning System.
- It uses satellites to find a device's location.
- It is widely used in smartphones and navigation apps.
What is a small add-on that adds extra features to a web browser called?
- A browser extension adds extra features to a browser.
- Examples include ad blockers and password managers.
- Extensions are installed from an official store.
What is a private browsing mode that does not save browsing history called?
- Incognito mode does not save browsing history.
- It also avoids saving cookies after the session ends.
- It does not make browsing fully anonymous online.
What type of malware secretly monitors a user’s activity without their knowledge?
- Spyware secretly monitors a user's activity.
- It can track keystrokes or browsing habits.
- It often installs without the user noticing.
What type of malware can spread across a network by copying itself without needing another file?
- A worm spreads across networks by copying itself.
- It does not need to attach to another file, unlike a virus.
- Worms can spread quickly across many computers.
What is illegal or unauthorized activity involving computers and networks called?
- Cybercrime is illegal activity involving computers or networks.
- It can include hacking, theft, and online fraud.
- Cybersecurity is the practice of defending against it.
What is a security attack that tricks people into revealing information, rather than exploiting technical weaknesses, called?
- Social engineering tricks people into revealing information.
- It relies on manipulation rather than technical hacking.
- Phishing is one common example of this technique.
What is the unauthorized exposure or theft of sensitive data from an organization called?
- A data breach is unauthorized exposure or theft of data.
- It can expose personal or financial information.
- Organizations use security measures to help prevent breaches.
Which of the following is generally recommended for creating a strong password?
- A strong password mixes letters, numbers, and symbols.
- It should not be easy to guess.
- Using different passwords for different accounts is safer.
What is a software delivery model where apps are hosted online and accessed by subscription called?
- Software as a Service (SaaS) hosts apps online.
- Users access them through a subscription over the internet.
- Many email and productivity tools use this model.
What is the practice of designing websites and apps to be usable by people with disabilities called?
- Accessibility means designing for people with disabilities.
- It can include screen-reader support and clear color contrast.
- It helps make digital products usable by more people.
Which device is used to connect multiple networks?
• A router directs data packets between computer networks.
• It uses IP addresses to determine the destination.
• It is essential for internet connectivity.
Which of these is a ‘Web Browser’?
• Firefox is an open-source web browser developed by Mozilla.
• It interprets HTML and CSS to display web pages.
• Other examples include Chrome, Safari, and Edge.
What is a ‘Packet’ in computer networking?
• Data is broken down into packets before transmission.
• Each packet contains header information (sender/receiver IP) and the data payload.
• Packets are reassembled at the destination.
Which of these is a ‘Cloud storage’ service?
• Cloud storage allows users to store files on remote servers over the internet.
• It enables file synchronization across multiple devices.
• Other examples include Dropbox and OneDrive.
Which of the following is a ‘Web Server’ software?
• Apache HTTP Server is one of the most widely used web servers.
• It processes incoming web requests and delivers content to browsers.
• It is a cornerstone of the internet's infrastructure.
What is ‘Bluetooth’?
• Bluetooth allows data transfer between nearby devices.
• It is commonly used for headphones, mice, and mobile data syncing.
• It uses radio frequency signals.
What is the role of a ‘System Administrator’?
• System admins ensure systems are secure, updated, and running efficiently.
• They manage user accounts and troubleshooting hardware.
• They are essential for corporate IT stability.
What does ‘ISP’ stand for?
• ISPs provide access to the internet for a monthly fee.
• They manage the infrastructure for broadband, fiber, or mobile connections.
• Common ISPs include companies like Comcast, AT&T, and various national providers.
Which of these is a ‘Search Engine’?
• Search engines index web pages to help users find information.
• They use complex algorithms to rank results.
• Others include Bing, DuckDuckGo, and Yahoo.
What is ‘Cybersecurity’?
• Cybersecurity includes defending networks, computers, and data.
• It involves encryption, firewalls, and regular security audits.
• It is increasingly critical in an interconnected world.
What is a ‘Subnet mask’ used for?
• Subnet masks help routers divide a larger network into smaller, manageable subnets.
• They distinguish between the network ID and the host ID.
• Essential for efficient network routing.
What is a ‘Client-Server’ architecture?
• The client (browser) sends a request to the server, which processes and returns data.
• This model is the basis for most internet applications.
• It promotes centralized resource management.
Which command is used to check network connectivity in Windows?
• 'ping' sends ICMP echo requests to a destination.
• It checks if a host is reachable and measures latency.
• It is the first tool used for network troubleshooting.
What is a ‘Bridge’ in networking?
• Bridges filter traffic between two network segments.
• They are used to reduce congestion by isolating traffic.
• Modern switches have largely replaced them.
What is a ‘Hub’ in networking?
• A hub sends incoming data to all ports regardless of destination.
• This creates network collisions and security risks.
• It is largely obsolete in modern professional environments.
What is ‘Encryption’ key?
• Public keys are shared, while private keys are kept secret.
• Without the key, encrypted data is indecipherable.
• Robust key management is essential for security.
Which command is used to display the IP configuration?
• 'ipconfig' displays current TCP/IP network configuration values.
• Useful for finding your IP address, subnet mask, and gateway.
• 'ifconfig' is the equivalent in Linux/macOS.
What is ‘Latency’ in networking?
• Low latency is critical for online gaming, VoIP, and real-time trading.
• It is the time it takes for a packet to travel from source to destination.
• Ping time is a common measurement of latency.
What is a ‘Gateway’?
• Gateways often perform protocol translation between networks (e.g., LAN to Internet).
• Often implemented as software or a hardware router.
• Essential for network interoperability.
What is a ‘VLAN’?
• VLANs logically partition a physical switch into multiple network segments.
• Increases security and reduces broadcast traffic.
• Essential for managing large, complex networks.