Computer Networks Interview Questions

1. Difference Between TCP and UDP

2. What is the OSI Model?

3. How Does DNS Work?

4. Difference Between HTTP and HTTPS

5. What is an IP Address?

6. What is Subnetting?

7. What is the TCP Three-Way Handshake?

8. What is a MAC Address?

9. What is ARP (Address Resolution Protocol)?

10. What is a Firewall?

11. What is NAT (Network Address Translation)?

12. What is DHCP (Dynamic Host Configuration Protocol)?

13. Router vs Switch: What is the Difference?

14. What is a Proxy Server?

15. What is Latency vs Bandwidth?

16. What is a VPN?

17. TCP/IP Model vs OSI Model

18. What is a Socket?

19. What is SSL/TLS?

20. HTTP/2 vs HTTP/1.1: What Changed?

21. IPv4 vs IPv6: What Are the Differences?

22. What is Packet Switching?

23. What is the HTTP Request Lifecycle?

24. What is a Port in Networking?

25. What is the Physical Layer (OSI Layer 1)?

26. What is the Data Link Layer (OSI Layer 2)?

27. What is the Network Layer (OSI Layer 3)?

28. What is the Transport Layer (OSI Layer 4)?

29. What is the Session Layer (OSI Layer 5)?

30. What is the Presentation Layer (OSI Layer 6)?

31. What is the Application Layer (OSI Layer 7)?

32. What is ICMP (Internet Control Message Protocol)?

33. What is IGMP (Internet Group Management Protocol)?

34. What is SNMP (Simple Network Management Protocol)?

35. What is FTP (File Transfer Protocol)?

36. What is SFTP (SSH File Transfer Protocol)?

37. What is SMTP (Simple Mail Transfer Protocol)?

38. What is IMAP (Internet Message Access Protocol)?

39. What is POP3 (Post Office Protocol version 3)?

40. What is Telnet?

41. What is SSH (Secure Shell)?

42. What is NTP (Network Time Protocol)?

43. What is LDAP (Lightweight Directory Access Protocol)?

44. What is RIP (Routing Information Protocol)?

45. What is OSPF (Open Shortest Path First)?

46. What is BGP (Border Gateway Protocol)?

47. What is MPLS (Multiprotocol Label Switching)?

48. VLAN Trunking Explained

49. What is STP (Spanning Tree Protocol)?

50. What is GRE (Generic Routing Encapsulation)?

51. What is TCP Flow Control and How Does It Work?

52. What is TCP Congestion Control?

53. What is TCP Slow Start?

54. What is TCP Window Scaling?

55. What is the Nagle Algorithm and When Should You Disable It?

56. What is TCP Fast Retransmit?

57. What is the TCP FIN Handshake (Connection Teardown)?

58. What is TCP Keepalive and How Does It Work?

59. What is a SYN Flood Attack?

60. TCP vs SCTP: What Is the Difference?

61. What Is HTTP/3 and QUIC?

62. HTTP Methods Explained (GET, POST, PUT, PATCH, DELETE)

63. HTTP Status Codes Explained in Detail

64. HTTP Headers Explained: Key Types and Uses

65. What is HTTP Keep-Alive?

66. What is Chunked Transfer Encoding?

67. What is HTTP Content Negotiation?

68. What is HTTP Pipelining?

69. How Do Cookies Work Over HTTP?

70. What is CORS and How Does It Work?

71. What are the Common DNS Record Types?

72. How Does DNS Caching Work?

73. Recursive vs Iterative DNS Queries: What is the Difference?

74. What is DNS over HTTPS (DoH)?

75. What is Reverse DNS?

76. DNS Load Balancing Explained

77. Symmetric vs Asymmetric Encryption

78. What is Public Key Infrastructure (PKI)?

79. What are Digital Certificates?

80. Explain the TLS Handshake in Detail

81. HTTPS vs HTTP: What Security Does HTTPS Add?

82. WPA vs WEP: How Do Wi-Fi Security Protocols Differ?

83. What is IPsec and How Does It Secure IP Traffic?

84. What is a DDoS Attack and How Is It Mitigated?

85. What is a Man-in-the-Middle Attack?

86. What is Packet Sniffing?

87. What is Port Scanning?

88. CIDR Notation Explained

89. Private vs Public IP Addresses

90. What is a Loopback Address?

91. Broadcast vs Multicast vs Unicast

92. What are the IPv6 Address Types?

93. MAC Address vs IP Address

94. What is a Default Gateway?

95. Hub vs Switch vs Router: What Is the Difference?

96. What is a Network Gateway?

97. What is a Modem and How Does It Differ from a Router?

98. What is a Load Balancer in Networking?

99. What are Network Topologies? Star, Bus, Ring, and Mesh Explained

100. LAN vs WAN vs MAN: What is the Difference?

101. VPN Types Explained: Remote Access vs Site-to-Site

102. What is SD-WAN (Software-Defined WAN)?

103. Bandwidth vs Throughput: What is the Difference?

104. What is Jitter in Networking?

105. What is Packet Loss?

106. What is MTU (Maximum Transmission Unit)?

107. What is IP Fragmentation in Networking?

108. What is QoS (Quality of Service)?

109. What is a CDN (Content Delivery Network)?

110. What are the Wi-Fi Standards (802.11a/b/g/n/ac/ax)?

111. What is Bluetooth and How Does It Work?

112. What are the Cellular Network Generations (2G to 5G)?

113. What is Ping and How Does It Work?

114. What is Traceroute and How Does It Work?

115. What is netstat?

116. What is nslookup?

117. What is Wireshark?

118. What is a Collision Domain?

119. What is a Broadcast Domain?

120. Circuit Switching vs Packet Switching

121. What is a VLAN?

122. Inter-VLAN Routing Explained

123. What is Link Aggregation?

124. What is a Subnet Mask?

125. What is Supernetting? CIDR Aggregation Explained

126. Classful vs Classless Addressing: What is the Difference?

127. What is Anycast Routing?

128. What is Multicast Routing?

129. What is NAT Traversal?

130. What is Port Forwarding and How Does It Work?

131. What is a DMZ Network?

132. What is 802.1X and How Does It Secure Network Access?

133. What is Network Access Control (NAC)?

134. What is RADIUS (Remote Authentication Dial-In User Service)?

135. What is TACACS+?

136. What is Kerberos in Networking?

137. What is a VPN Tunnel?

138. Site-to-Site vs Remote-Access VPN: What is the Difference?

139. What is WireGuard?

140. What is OpenVPN?

141. What is IPsec vs SSL VPN?

142. What is a Captive Portal?

143. What is Network Segmentation?

144. What is Zero Trust Networking?

145. What is Software-Defined Networking (SDN)?

146. What is Network Function Virtualization (NFV)?

147. What is a Network Interface Card (NIC)?

148. What is Full-Duplex vs Half-Duplex Communication?

149. What is Ethernet?

150. What is the Ethernet Frame Format?

151. What is CSMA/CD?

152. What is CSMA/CA?

153. What is a Crossover Cable?

154. Straight-Through vs Crossover Cable: What is the Difference?

155. What is Power over Ethernet (PoE)?

156. What is a Network Bridge?

157. What is a Repeater?

158. What is a Network Hub?

159. What is Structured Cabling?

160. Fiber Optic vs Copper Cabling: What is the Difference?

161. Single-Mode vs Multimode Fiber: What is the Difference?

162. What is a Patch Panel?

163. What is a Router Routing Table?

164. Static vs Dynamic Routing: What is the Difference?

165. What is Route Summarization?

166. What is Administrative Distance?

167. Distance-Vector vs Link-State Routing

168. What is Equal-Cost Multipath (ECMP)?

169. What is Policy-Based Routing (PBR)?

170. What is a Routing Loop?

171. What is Split Horizon?

172. What is HSRP (Hot Standby Router Protocol)?

173. What is VRRP (Virtual Router Redundancy Protocol)?

174. What is GLBP (Gateway Load Balancing Protocol)?

175. What are First Hop Redundancy Protocols (FHRP)?

176. What is EtherChannel?

177. What are Jumbo Frames?

178. What is Path MTU Discovery (PMTUD)?

179. What is a Network Socket vs a Port?

180. What Are Ephemeral Ports?

181. What Are Well-Known Ports?

182. What is the TCP State Machine?

183. How Does TCP Connection Teardown Work?

184. What Are Common UDP Use Cases?

185. When Should You Use TCP vs UDP?

186. What is the QUIC Protocol?

187. What is WebRTC and How Does its Networking Work?

188. What is the WebSocket Protocol?

189. HTTP vs WebSocket: What is the Difference?

190. What is a Reverse Proxy?

191. Forward Proxy vs Reverse Proxy: What is the Difference?

192. What is an API Gateway (from a Networking Perspective)?

193. What is a Service Mesh (from a Networking Perspective)?

194. What is NAT and Port Translation (NAPT)?

195. What is Carrier-Grade NAT (CGNAT)?

196. What Are IPv6 Transition Mechanisms?

197. What is 6to4 Tunneling?

198. What is Dual Stack Networking?

199. What is SLAAC (Stateless Address Autoconfiguration)?

200. DHCPv6 vs SLAAC: What is the Difference?

201. What is Neighbor Discovery Protocol (NDP)?

202. What is a Router Advertisement (RA)?

203. What is a DNS Zone?

204. What is a DNS Resolver?

205. Authoritative vs Recursive DNS Server: What is the Difference?

206. What is DNSSEC?

207. What is DNS Cache Poisoning?

208. What is a CDN Edge Node?

209. What is Anycast DNS?

210. What is Geo Load Balancing?

211. What is a Load Balancer Algorithm?

212. Round Robin vs Least Connections Load Balancing

213. What is Health Checking in Networking?

214. What is Session Persistence?

215. What is a Network Firewall Rule?

216. Stateful vs Stateless Firewall: What is the Difference?

217. What is an Intrusion Detection System (IDS)?

218. What is an Intrusion Prevention System (IPS)?

219. What is Network Traffic Analysis?

220. What is Deep Packet Inspection (DPI)?

221. What is a Honeypot in Networking?

222. What is ARP Spoofing?

223. What is DNS Spoofing?

224. What is a Replay Attack?