TCP/IP, DNS, HTTP — the questions every interviewer loves to ask.

Q1.How many layers does the OSI reference model have?

Q2.Which OSI layer is responsible for MAC addresses and frame delivery within a local network?

Q3.Which OSI layer handles end-to-end communication, error recovery, and flow control?

Q4.IP addressing and routing packets across multiple networks is handled by which OSI layer?

Q5.Which OSI layer is responsible for data encryption, compression, and format translation?

Q6.Which OSI layer establishes, manages, and terminates sessions between applications?

Q7.A network hub operates at which OSI layer?

Q8.Which OSI layer converts bits into electrical, light, or radio signals for transmission?

Q1.How many layers does the TCP/IP model have?

Q2.The "Internet layer" in TCP/IP corresponds to which OSI layer?

Q3.TCP/IP's Application layer effectively covers which OSI layers?

Q4.Which model is actually implemented in real-world networking equipment and protocols?

Q1.What does TCP's three-way handshake accomplish?

Q2.Which of the following typically uses UDP instead of TCP?

Q3.TCP guarantees reliable delivery primarily through:

Q4.Which statement about UDP is true?

Q5.TCP's "sliding window" mechanism is primarily used for:

Q6.Which port number is the default for HTTP?

Q7.What does the SYN flag in a TCP segment indicate?

Q8.Which protocol would you choose for live video streaming where occasionally dropping a frame is acceptable?

Q1.How many bits make up an IPv4 address?

Q2.How many bits make up an IPv6 address?

Q3.What is the subnet mask for a /24 network?

Q4.Which IP address range belongs to Class C?

Q5.Which of the following is a private IP address per RFC 1918?

Q6.What does NAT (Network Address Translation) do?

Q7.What does ARP (Address Resolution Protocol) do?

Q8.What is DHCP used for?

Q1.What is the primary purpose of DNS?

Q2.Which protocol is used to send (not retrieve) email?

Q3.FTP uses which two port numbers for control and data?

Q4.What is the key difference between HTTPS and HTTP?

Q5.What is the default port for SSH?

Q6.When a browser loads a web page, which protocol does it use to actually fetch the HTML?

Q7.What is ICMP (Internet Control Message Protocol) used for?

Q8.What does the TTL (Time to Live) field in an IP packet control?

Q1.CRC (Cyclic Redundancy Check) is used for:

Q2.With even parity, the total number of 1 bits (data + parity bit) is:

Q3.Which error-control technique can both detect AND correct bit errors?

Q4.In the Stop-and-Wait protocol, the sender:

Q5.How does the sliding window protocol improve on Stop-and-Wait?

Q6.In Go-Back-N (GBN) ARQ, if frame 4 in a window is lost, what happens?

Q7.What does TCP's "slow start" congestion control mechanism do?

Q8.What's the difference between flow control and congestion control?

Q1.Which network device operates at Layer 2, forwarding frames based on MAC addresses?

Q2.Which routing protocol uses a distance-vector algorithm?

Q3.OSPF computes shortest paths using which algorithm?

Q4.BGP (Border Gateway Protocol) is primarily used for:

Q5.What is a "default gateway"?

Q6.What is the main purpose of subnetting?