Top 100 Most Asked Computer Networks Interview Questions

A comprehensive collection of Computer Networking interview questions covering basics, OSI layers, protocols, and IP addressing. Perfect for technical screenings.

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1.What is Computer Networking?

2.What is the difference between Hub, Switch, and Router?

3.What is the difference between TCP and UDP?

4.What is IP Address? Explain IPv4 and IPv6.

5.What is MAC Address? How is it different from IP Address?

6.What is the difference between Public and Private IP Address?

7.What is a Port Number? Give examples of common ports.

8.What is DNS and how does it work?

9.What is DHCP? How does it assign IP addresses?

10.What is the difference between HTTP and HTTPS?

11.What is Gateway?

12.What is Subnet Mask?

13.What is NAT (Network Address Translation)?

14.What is localhost and 127.0.0.1?

15.What is Bandwidth and Latency?

16.What is the OSI Model? Name all 7 layers.

17.What is the difference between OSI and TCP/IP Model?

18.What happens at each layer of OSI Model?

19.Which layer is responsible for routing?

20.Which layer is responsible for error detection?

21.What is the function of Transport Layer?

22.What is the function of Network Layer?

23.What is the function of Data Link Layer?

24.What is Encapsulation and Decapsulation?

25.What is PDU (Protocol Data Unit)?

26.Which protocols work at which OSI layer?

27.What is the difference between Layer 2 and Layer 3 Switch?

28.What is the Application Layer responsible for?

29.Why do we need a layered network model?

30.What is the Session Layer used for?

31.Explain TCP 3-Way Handshake in detail.

32.What is SYN, SYN-ACK, and ACK?

33.How is TCP connection terminated? (4-Way Handshake)

34.What is the difference between Connection-Oriented and Connectionless Protocol?

35.Why does DNS use UDP instead of TCP?

36.What is ARP (Address Resolution Protocol)?

37.What is ICMP? What does ping use?

38.What is the difference between FTP and SFTP?

39.What is SMTP, POP3, and IMAP?

40.What is SSH and which port does it use?

41.What is Telnet? Why is SSH preferred over Telnet?

42.What is HTTP methods (GET, POST, PUT, DELETE)?

43.What is HTTP Status Codes? (200, 404, 500, etc.)

44.What is SSL/TLS? How does HTTPS work?

45.What is a Socket?

46.What are IP Address Classes (A, B, C, D, E)?

47.What is Subnetting and why is it needed?

48.How do you calculate Subnet Mask?

49.What is CIDR notation?

50.What are the private IP address ranges?

51.What is the difference between Static and Dynamic IP?

52.What is APIPA (Automatic Private IP Addressing)?

53.What is Loopback Address?

54.What is Broadcast Address?

55.What is Network Address?

56.What is the difference between IPv4 and IPv6?

57.Why do we need IPv6?

58.What is the size of IPv4 and IPv6 addresses?

59.How many hosts can a /24 network have?

60.What is Supernetting?

61.What is Routing?

62.What is a Routing Table?

63.What is the difference between Static and Dynamic Routing?

64.What is Default Gateway?

65.What are Routing Protocols? Name a few.

66.What is RIP, OSPF, and BGP?

67.What is the difference between Distance Vector and Link State Routing?

68.What is Hop Count?

69.What is TTL (Time To Live)?

70.What is the difference between Router and Switch?

71.What is VLAN? Why is it used?

72.What is Spanning Tree Protocol (STP)?

73.What is the difference between Circuit Switching and Packet Switching?

74.What is a Virtual Circuit?

75.What is the difference between Layer 2 and Layer 3 devices?

76.What is Firewall? What are its types?

77.What is the difference between Stateful and Stateless Firewall?

78.What is VPN and how does it work?

79.What is Encryption? Explain Symmetric and Asymmetric Encryption.

80.What is the difference between Encryption and Hashing?

81.What is SSL Certificate?

82.What is DoS and DDoS attack?

83.What is the difference between DoS and DDoS?

84.How to prevent DDoS attacks?

85.What is Man-in-the-Middle (MITM) Attack?

86.What is DNS Spoofing?

87.What is Phishing?

88.What is the difference between Virus, Worm, and Trojan?

89.What is SQL Injection?

90.What is a Brute Force Attack?

91.How does a packet travel from source to destination? (End-to-End)

92.What happens when you type www.google.com in your browser?

93.What is Load Balancer? What are Load Balancing algorithms?

94.What is the difference between Load Balancer and Reverse Proxy?

95.What is CDN (Content Delivery Network)?

96.What is the difference between Horizontal and Vertical Scaling?

97.What is Caching? What are different types of caching?

98.Explain ping, traceroute, and netstat commands.

99.What is the difference between Unicast, Broadcast, and Multicast?

100.What is the difference between LAN, MAN, and WAN?