Networking Interview Questions

  1. What is a Computer Network?
    • A computer network is a set of interconnected devices that share resources and information.
  2. What is the OSI Model?
    • The OSI (Open Systems Interconnection) Model is a conceptual framework used to understand network communication. It consists of seven layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.
  3. Difference between TCP and UDP?
    • TCP (Transmission Control Protocol) provides reliable, ordered, and error-checked delivery of data, while UDP (User Datagram Protocol) is faster but offers no guarantees of delivery or ordering.
  4. What is DHCP?
    • DHCP (Dynamic Host Configuration Protocol) is a network protocol used to assign IP addresses and other network configuration parameters to devices on a network automatically.
  5. What is DNS?
    • DNS (Domain Name System) is a system that translates domain names into IP addresses, allowing users to access websites by name rather than remembering IP addresses.
  6. What is a subnet mask?
    • A subnet mask is used to divide an IP address into network and host portions. It determines the network portion of an IP address.
  7. What is a VLAN?
    • VLAN (Virtual Local Area Network) is a logical grouping of devices in a network, allowing for segmentation and isolation while behaving as though they are on the same network.
  8. Difference between a hub, switch, and router?
    • A hub operates at the physical layer, a switch operates at the data link layer, and a router operates at the network layer of the OSI model. A hub forwards data to all devices in a network, a switch forwards data based on MAC addresses, and a router forwards data between different networks.
  9. What is NAT?
    • NAT (Network Address Translation) is a technique used to modify network address information in packet headers while they are in transit across a traffic routing device, typically to map private IP addresses to public ones.
  10. What is ARP?
    • ARP (Address Resolution Protocol) is used to map IP addresses to MAC addresses in a local network.
  11. What is the purpose of a firewall?
    • A firewall is a security device or software that monitors and controls incoming and outgoing network traffic based on predetermined security rules, helping to prevent unauthorized access and attacks.
  12. What is the difference between a public IP and a private IP?
    • Public IPs are globally unique and routable on the internet, while private IPs are used within a private network and are not routable on the internet.
  13. What is a MAC address?
    • A MAC (Media Access Control) address is a unique identifier assigned to a network interface controller for communications on the physical network segment.
  14. Explain the concept of Bandwidth?
    • Bandwidth refers to the maximum data transfer rate of a network or internet connection, usually measured in bits per second (bps), kilobits per second (kbps), or megabits per second (Mbps).
  15. What is a DHCP lease time?
    • DHCP lease time is the duration for which a DHCP client can use an IP address assigned by a DHCP server before it must renew the lease.
  16. What is the difference between symmetric and asymmetric encryption?
    • Symmetric encryption uses the same key for both encryption and decryption, while asymmetric encryption uses different keys for encryption and decryption.
  17. Explain the three-way handshake in TCP?
    • The three-way handshake is a method used in TCP to establish a connection between a client and a server. It involves SYN, SYN-ACK, and ACK packets exchanged between the client and server to establish and confirm the connection.
  18. What is the purpose of the subnet?
    • Subnetting allows for the division of a single, large network into smaller, more manageable subnetworks, improving efficiency, security, and performance.
  19. What is ICMP?
    • ICMP (Internet Control Message Protocol) is a supporting protocol used by network devices, including routers, to send error messages and operational information, such as ping requests and replies.
  20. Explain the difference between half-duplex and full-duplex communication?
    • In half-duplex communication, data can be transmitted and received but not simultaneously, while in full-duplex communication, data can be transmitted and received simultaneously.
  21. What is a proxy server?
    • A proxy server acts as an intermediary between clients and other servers, forwarding requests and responses while providing various functionalities like caching, security, and anonymity.
  22. What is a DNS server?
    • A DNS server is a specialized server that translates domain names into IP addresses and vice versa, enabling users to access websites using human-readable names.
  23. What is a MAC flooding attack?
    • MAC flooding is a network attack where the attacker floods the switch with a large number of MAC addresses to overload the switch’s address table, causing it to function like a hub, allowing the attacker to sniff network traffic.
  24. Explain the difference between a hub and a switch?
    • A hub operates at the physical layer of the OSI model and broadcasts data to all connected devices, while a switch operates at the data link layer and selectively forwards data based on MAC addresses, improving network efficiency.
  25. What is SSL?
    • SSL (Secure Sockets Layer) is a protocol that provides secure and encrypted communication over a computer network, commonly used to secure web traffic.
  26. What is a default gateway?
    • A default gateway is a router or device used to forward traffic from a local network to destinations outside the network.
  27. Explain the difference between static and dynamic IP addresses?
    • A static IP address is manually assigned to a device and remains unchanged, while a dynamic IP address is assigned automatically by a DHCP server and can change over time.
  28. What is a MAC address table?
    • A MAC address table is a table maintained by a switch that contains MAC addresses associated with specific switch ports, used to forward frames efficiently.
  29. What is the purpose of a MAC address?
    • A MAC address uniquely identifies a network interface card (NIC) on a network and is used for communication within a network segment.
  30. What is a DMZ?
    • A DMZ (Demilitarized Zone) is a network segment that sits between an internal network and an external network, often used to host publicly accessible services while providing an added layer of security.
  31. What is ARP poisoning?
    • ARP poisoning (also known as ARP spoofing) is a type of attack where the attacker sends false Address Resolution Protocol (ARP) messages over a local area network, linking their MAC address to a legitimate IP address to intercept data.
  32. What is the purpose of a router in a network?
    • A router is a networking device that forwards data packets between computer networks. It connects different networks and determines the best path for data to travel.
  33. Explain the difference between a hub and a repeater?
    • A hub is a multi-port device that operates at the physical layer and forwards data to all connected devices, while a repeater simply regenerates incoming signals to extend the distance of a network segment.
  34. What is the purpose of NAT traversal?
    • NAT traversal allows devices on a private network to communicate with devices outside the network by overcoming the limitations imposed by NAT.
  35. What is a broadcast storm?
    • A broadcast storm occurs when broadcast or multicast packets create excessive traffic on a network, consuming available bandwidth and causing network performance issues.

These questions cover various aspects of computer networking and are commonly asked in interviews to assess an individual’s understanding and knowledge of networking concepts and protocols.

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