Frequently Asked Computer Networking Interview Questions for L1 and Junior Network Engineers

Basic Networking Concepts

1. What is a network?

• Scope of Answer: Explain the basic definition and components of a network.
• Key Points: Connection of devices, communication, data sharing, nodes, and links.

2. What is an IP address?

• Scope of Answer: Describe what an IP address is and its purpose in networking.
• Key Points: Unique identifier, Internet Protocol, IPv4, IPv6.

3. What is the difference between IPv4 and IPv6?

• Scope of Answer: Highlight the key differences between IPv4 and IPv6.
• Key Points: Address length, format, address space, NAT usage.

4. What is a MAC address?

• Scope of Answer: Define a MAC address and its use in networking.
• Key Points: Media Access Control, unique identifier, hardware address, network interface.

5. Explain the OSI model.

• Scope of Answer: Describe the OSI model and its layers.
• Key Points: Seven layers, functions, application, presentation, session, transport, network, data link, physical.

6. What is a subnet mask?

• Scope of Answer: Explain the concept of a subnet mask and its purpose.
• Key Points: Subnetting, network portion, host portion, IPv4.

7. What is DNS?

• Scope of Answer: Describe the Domain Name System and its function.
• Key Points: Name resolution, domain names, IP addresses, DNS servers.

8. What is DHCP?

• Scope of Answer: Explain the Dynamic Host Configuration Protocol and its use.
• Key Points: Automatic IP address assignment, DHCP server, lease time, network configuration.

9. What is a gateway?

• Scope of Answer**: Define a gateway and its role in networking.
• Key Points: Network point, access to another network, default gateway.

10. What is NAT?

• Scope of Answer: Describe Network Address Translation and its purpose.
• Key Points: IP address mapping, private to public addresses, types of NAT.

Network Devices

11. What is a router?

• Scope of Answer: Define a router and its primary function.
• Key Points: Network traffic management, path selection, connecting networks.

12. What is a switch?

• Scope of Answer: Explain what a switch is and how it operates.
• Key Points: Data packet forwarding, MAC address table, VLANs, collision domains.

13. What is a firewall?

• Scope of Answer: Describe the function of a firewall in network security.
• Key Points: Traffic filtering, security policies, types (hardware, software).

14. What is a modem?

• Scope of Answer: Define a modem and its role in internet connectivity.
• Key Points: Modulation, demodulation, analog to digital conversion, ISP connection.

15. What is an access point?

• Scope of Answer: Explain what a wireless access point is.
• Key Points: Wireless network extension, Wi-Fi connectivity, client devices.

16. What is a network hub?

• Scope of Answer: Describe a network hub and how it functions.
• Key Points: Data broadcasting, collision domains, simplicity, limited use.

17. What is a network interface card (NIC)?

• Scope of Answer: Explain the role of a NIC in a computer network.
• Key Points: Hardware component, network connectivity, MAC address.

18. What is a VPN?

• Scope of Answer: Define a Virtual Private Network and its purpose.
• Key Points: Secure connections, remote access, encryption, tunneling protocols.

19. What is a load balancer?

• Scope of Answer: Describe the function of a load balancer in networking.
• Key Points: Distributing traffic, high availability, scalability, types (hardware, software).

20. What is a proxy server?

• Scope of Answer: Explain the role of a proxy server.
• Key Points: Intermediate server, request forwarding, anonymity, content filtering.

Network Protocols

21. What is TCP/IP?

• Scope of Answer: Define TCP/IP and its importance in networking.
• Key Points: Transmission Control Protocol, Internet Protocol, suite of protocols, communication.

22. What is HTTP/HTTPS?

• Scope of Answer: Explain the Hypertext Transfer Protocol and its secure version.
• Key Points: Web communication, data transfer, SSL/TLS encryption (HTTPS).

23. What is FTP?

• Scope of Answer: Describe the File Transfer Protocol and its use.
• Key Points: File transfer, client-server model, FTP ports, security concerns.

24. What is SMTP?

• Scope of Answer: Explain the Simple Mail Transfer Protocol.
• Key Points: Email transmission, server communication, email clients.

25. What is SNMP?

• Scope of Answer: Define the Simple Network Management Protocol.
• Key Points: Network management, monitoring, SNMP agents, MIBs.

26. What is ICMP?

• Scope of Answer: Describe the Internet Control Message Protocol.
• Key Points: Error reporting, network diagnostics, ping, traceroute.

27. What is ARP?

• Scope of Answer: Explain the Address Resolution Protocol.
• Key Points: IP to MAC address mapping, ARP cache, ARP request and reply.

28. What is NTP?

• Scope of Answer: Define the Network Time Protocol.
• Key Points: Time synchronization, NTP servers, clock accuracy.

29. What is PPP?

• Scope of Answer: Describe the Point-to-Point Protocol.
• Key Points: Direct connection, authentication, encapsulation.

30. What is TFTP?

• Scope of Answer: Explain the Trivial File Transfer Protocol.
• Key Points: Simple file transfer, UDP, limited features.

Network Security

31. What is encryption?

• Scope of Answer: Define encryption and its importance in network security.
• Key Points: Data protection, cryptographic algorithms, symmetric and asymmetric encryption.

32. What is a VPN?

• Scope of Answer: Explain the concept of a Virtual Private Network.
• Key Points: Secure communication, remote access, tunneling protocols.

33. What is SSL/TLS?

• Scope of Answer: Describe the Secure Sockets Layer and Transport Layer Security protocols.
• Key Points: Data encryption, secure communication, HTTPS.

34. What is a DDoS attack?

• Scope of Answer: Define Distributed Denial of Service and its impact.
• Key Points: Attack on network availability, multiple sources, mitigation techniques.

35. What is a firewall?

• Scope of Answer: Explain the purpose and function of a firewall.
• Key Points: Network security, traffic filtering, types of firewalls.

36. What is an IDS/IPS?

• Scope of Answer: Describe Intrusion Detection and Prevention Systems.
• Key Points: Network monitoring, threat detection, automatic responses.

37. What is malware?

• Scope of Answer: Define malware and its types.
• Key Points: Malicious software, viruses, worms, trojans, spyware.

38. What is phishing?

• Scope of Answer: Explain phishing attacks and their prevention.
• Key Points: Social engineering, fraudulent emails, user education.

39. What is a security audit?

• Scope of Answer: Describe the purpose and process of a security audit.
• Key Points: Network assessment, vulnerability identification, compliance.

40. What is multi-factor authentication (MFA)?

• Scope of Answer: Explain the concept and benefits of MFA.
• Key Points: Enhanced security, multiple verification methods, reduced risk.

Network Management

41. What is network monitoring?

• Scope of Answer: Define network monitoring and its importance.
• Key Points: Performance tracking, fault detection, network management tools.

42. What is bandwidth?

• Scope of Answer: Explain the concept of bandwidth in networking.
• Key Points: Data transfer rate, network capacity, Mbps, Gbps.

43. What is QoS?

• Scope of Answer: Describe Quality of Service and its role in networking.
• Key Points: Traffic prioritization, bandwidth management, latency, jitter.

44. What is a VLAN?

• Scope of Answer: Define a Virtual Local Area Network.
• Key Points: Network segmentation, security, broadcast domain reduction.

45. What is network segmentation?

• Scope of Answer: Explain the concept of network segmentation.
• Key Points: Traffic isolation, improved performance, enhanced security.

46. What is a DMZ?

• Scope of Answer: Describe a Demilitarized Zone in networking.
• Key Points: Buffer zone, external services, security layer.

47. What is load balancing?

• Scope of Answer: Define load balancing and its use.
• Key Points: Traffic distribution, server utilization, high