Basic Questions
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What is a computer network?
A computer network is a system of interconnected devices that communicate and share resources using protocols over wired or wireless connections. - What are the types of computer networks?
- LAN (Local Area Network) – Covers a small area like a home, school, or office.
- MAN (Metropolitan Area Network) – Covers a city or a large campus.
- WAN (Wide Area Network) – Covers large geographic areas like countries or continents (e.g., the Internet).
- What is the difference between the Internet and an intranet?
- Internet is a global network connecting millions of private, public, academic, business, and government networks.
- Intranet is a private network restricted to an organization for internal communication.
- What are the different types of network topologies?
- Bus – Uses a single backbone cable; failure in the cable affects the entire network.
- Star – All devices connect to a central hub or switch; failure of the hub affects the network.
- Ring – Each device connects to two others, forming a ring; failure in one device can break the loop.
- Mesh – Every device connects to every other device, ensuring redundancy.
- Hybrid – A mix of two or more topologies.
- What is a MAC address?
A Media Access Control (MAC) address is a unique identifier assigned to a network interface card (NIC) by the manufacturer. It is used for communication within a network segment.
OSI & TCP/IP Model Questions
- What are the seven layers of the OSI model?
- Physical – Transmission of raw data over the medium.
- Data Link – Handles error detection and framing (e.g., MAC address).
- Network – Manages routing and IP addressing.
- Transport – Ensures reliable transmission (e.g., TCP, UDP).
- Session – Establishes and maintains sessions between applications.
- Presentation – Formats, encrypts, and compresses data.
- Application – Provides network services to end users (e.g., HTTP, FTP).
- Compare TCP and UDP.
- TCP (Transmission Control Protocol): Reliable, connection-oriented, ensures data delivery (e.g., web browsing, email).
- UDP (User Datagram Protocol): Unreliable, connectionless, faster, used in real-time applications (e.g., video streaming, VoIP).
- What is encapsulation in networking?
Encapsulation is the process of adding headers and trailers to data as it moves through the OSI layers before transmission.
IP Addressing & Routing
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What is an IP address?
An IP address is a numerical label assigned to a device for identification and communication over a network. - Differentiate between IPv4 and IPv6.
- IPv4: 32-bit address, uses decimal notation, supports ~4.3 billion addresses.
- IPv6: 128-bit address, uses hexadecimal notation, supports trillions of addresses.
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What is a subnet mask?
A subnet mask separates the network and host portions of an IP address to determine which devices belong to the same subnet. - What is the difference between static and dynamic IP addresses?
- Static IP: Manually assigned, does not change, used in servers.
- Dynamic IP: Assigned by DHCP (Dynamic Host Configuration Protocol), changes periodically.
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What is a default gateway?
A default gateway is a router that connects a local network to external networks, forwarding packets that need to reach other networks. - What is NAT (Network Address Translation)?
NAT allows multiple devices on a local network to share a single public IP address, improving security and conserving IP addresses.
Networking Devices & Protocols
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What is the function of a router?
A router forwards data between different networks based on IP addresses. -
What is a switch?
A switch operates at the data link layer, directing data only to the intended recipient, improving efficiency over hubs. - What is the difference between a hub, switch, and router?
- Hub: Broadcasts data to all devices in a network.
- Switch: Sends data only to the intended device.
- Router: Connects different networks and directs traffic based on IP addresses.
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What is ARP (Address Resolution Protocol)?
ARP maps an IP address to a MAC address for communication within a network. -
What is DNS (Domain Name System)?
DNS translates domain names (e.g., google.com) into IP addresses (e.g., 142.250.183.238). - What is DHCP (Dynamic Host Configuration Protocol)?
DHCP automatically assigns IP addresses to devices in a network.
Security & Miscellaneous Questions
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What is a firewall?
A firewall is a security system that monitors and controls incoming and outgoing network traffic based on security rules. -
What is a VPN (Virtual Private Network)?
A VPN encrypts data and routes it through a secure server, masking the user’s actual IP address for privacy. -
What is a proxy server?
A proxy server acts as an intermediary between a user and the internet, often used for security, anonymity, or content filtering. -
What is bandwidth?
Bandwidth is the maximum data transfer rate of a network or internet connection, measured in bps (bits per second). -
What is latency?
Latency is the time taken for a data packet to travel from source to destination, usually measured in milliseconds (ms). -
What is ping?
Ping is a network command that tests the reachability of a host and measures round-trip time (RTT). -
What is packet switching?
Packet switching breaks data into packets that travel independently to their destination, allowing efficient and fast transmission (e.g., the Internet). - What is the difference between unicast, multicast, and broadcast?
- Unicast – One-to-one communication.
- Multicast – One-to-many (specific group).
- Broadcast – One-to-all devices in a network.
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What is a man-in-the-middle (MITM) attack?
A MITM attack occurs when an attacker secretly intercepts and possibly alters communication between two parties. - What is a denial-of-service (DoS) attack?
A DoS attack floods a network or server with excessive traffic to disrupt normal operation.
Bonus: Tricky Questions
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Why is TCP more reliable than UDP?
TCP provides error checking, retransmissions, congestion control, and three-way handshake, ensuring data is delivered correctly. -
How does HTTPS work?
HTTPS uses SSL/TLS encryption to secure communication between a client and a server, preventing eavesdropping and data tampering. -
What happens when you type a URL in a browser and press Enter?
- DNS resolves the domain name to an IP address.
- Browser establishes a TCP connection with the server.
- HTTP/HTTPS request is sent to the server.
- Server responds with the requested webpage.
- Browser renders the webpage.
Network Devices and OSI Layers
- Which device operates at the Physical Layer (Layer 1)?
- Hubs, Repeaters, Cables (Ethernet, Fiber Optic), and Network Interface Cards (NICs) work at the Physical Layer.
- They deal with raw data transmission, signals, and bit representation.
- Which device operates at the Data Link Layer (Layer 2)?
- Switches and Bridges operate at the Data Link Layer.
- They use MAC addresses for forwarding frames within a network.
- Which device operates at the Network Layer (Layer 3)?
- Routers and Layer 3 Switches operate at the Network Layer.
- They use IP addresses for routing packets across different networks.
- Which device operates at the Transport Layer (Layer 4)?
- Firewalls and Load Balancers work at the Transport Layer.
- They handle port numbers, segmentation, and flow control (e.g., TCP and UDP).
- Which device operates at the Session Layer (Layer 5)?
- Some Gateways and Proxies operate at the Session Layer.
- They establish, maintain, and terminate communication sessions.
- Which device operates at the Presentation Layer (Layer 6)?
- Encryption/Decryption Devices (SSL/TLS) and Data Compressors work at the Presentation Layer.
- They format data for compatibility and security.
- Which device operates at the Application Layer (Layer 7)?
- Web Servers, Email Servers, Proxies, and DNS Servers operate at the Application Layer.
- They interact with end-user applications like browsers, email clients, and file transfers.
More Layer-Specific Questions
- What is the role of a repeater in networking?
- A repeater regenerates and amplifies weak signals to extend transmission distances.
- It operates at Layer 1 (Physical Layer).
- What is the main function of a switch?
- A switch intelligently forwards data to the correct device using MAC addresses.
- It operates at Layer 2 (Data Link Layer).
- How does a router differ from a switch?
- A router operates at Layer 3 (Network Layer) and routes packets based on IP addresses.
- A switch operates at Layer 2 (Data Link Layer) and forwards frames using MAC addresses.
- What is a Layer 3 switch?
- A Layer 3 switch performs both switching (Layer 2) and routing (Layer 3) functions.
- It allows communication between different subnets.
- How does a firewall work, and at which layer does it operate?
- A firewall monitors and filters incoming/outgoing traffic based on security rules.
- It primarily operates at Layer 4 (Transport Layer) but can extend to Layer 7 (Application Layer) in advanced configurations.
- What is the function of a proxy server, and which OSI layer does it belong to?
- A proxy server acts as an intermediary between clients and servers, providing caching, security, and anonymity.
- It operates at Layer 7 (Application Layer).
- At which layer does NAT (Network Address Translation) work?
- NAT operates at Layer 3 (Network Layer) because it modifies IP addresses for internet access.
- What layer does DNS work in?
- DNS (Domain Name System) works at Layer 7 (Application Layer) because it translates domain names into IP addresses.
- At which OSI layer does SSL/TLS encryption work?
- SSL/TLS encryption operates at Layer 6 (Presentation Layer) for encryption and decryption.
Tricky Layer Questions
- Can a device work at multiple OSI layers?
- Yes, some devices like firewalls, proxies, and gateways operate at multiple layers.
- What is the highest OSI layer that a switch can operate at?
- A basic switch operates at Layer 2, but Layer 3 switches can function at the Network Layer.
- What happens if a router fails?
- Network packets cannot be forwarded between different networks, breaking external communication.
- Why are hubs considered obsolete?
- Hubs send data to all devices, causing network congestion, whereas switches send data only to intended recipients.
This should cover all the must-know viva questions about network devices and OSI layers. Let me know if you need more! 🚀