NPTEL Ethical Hacking Week 2 Assignment Answers 2024 (July-October)

The National Programme on Technology Enhanced Learning (NPTEL) provides a robust and comprehensive course on Ethical Hacking, aiming to equip participants with advanced skills in network security and defense mechanisms. Week 2 of this course delves into the intricacies of IP addressing and TCP/IP protocols, foundational elements crucial for any aspiring ethical hacker. Below, we present a detailed analysis and answers to the Week 2 assignment questions for the 2024 (July-October) session.

Question 1: Which of the following statement(s) is/are true for transparent fragmentation?

• Answer: a. The subsequent networks are aware that the fragmentation has occurred. c. Each fragment is treated as an independent packet.
• Explanation: Transparent fragmentation ensures that each fragment of a packet is treated independently by subsequent networks, which are aware of the fragmentation but do not need to reassemble the packets.

Question 2: For reassembling the fragmented packets at the final destination, which of the following header field(s) is(are) used by IP?

• Answer: a. Fragment offset e. Identification
• Explanation: The Fragment Offset field indicates the position of the fragment in the original packet, while the Identification field helps in identifying which fragments belong to the same original packet.

Question 3: An IP packet arrives at the final destination with the D flag set as 1. Which of the following statement is true about the packet?

• Answer: a. The packet has not been fragmented.
• Explanation: The D flag (Don't Fragment flag) set to 1 means that the packet should not be fragmented, so if the packet arrives with this flag, it indicates no fragmentation has occurred.

Question 4: In an IP packet, the value of HLEN is 8, and the total size of IP packet is 1500 bytes. The number of data bytes in the packet will be ________.

• Answer: 1480
• Explanation: HLEN value of 8 means a header length of 32 bytes (8 * 4). Therefore, the data bytes are calculated as 1500 (total size) - 32 (header size) = 1468 bytes.

Question 5: Which of the following statement(s) is/are false for IP addressing?

• Answer: d. None of these
• Explanation: All the provided statements about IP addressing are true:
  • Each host connected to the Internet is defined by an IP address.
  • IP address consists of two parts: network number and host number.
  • When a packet is routed to the destination network, only the network number is used.

Question 6: Which address classes do the IP addresses 10.16.75.12 and 192.10.85.120 belong to?

• Answer: d. Class A and Class C
• Explanation: The IP address 10.16.75.12 falls under Class A (range 1.0.0.0 to 127.255.255.255), and 192.10.85.120 falls under Class C (range 192.0.0.0 to 223.255.255.255).

Question 7: Which of the following IP addresses does not represent a broadcast address?

• Answer: e. 192.168.255.255
• Explanation: 192.168.255.255 is a broadcast address. A non-broadcast address would be a specific, usable IP address within a subnet.

Question 8: Which of the following statement(s) is/are false for flag bits in TCP header?

• Answer: d. None of these
• Explanation: All provided statements about TCP header flag bits are true:
  • SYN=1 and ACK=0 represents a connection request message.
  • SYN=1 and ACK=1 represents a connection confirmation message.
  • RST bit is used to reset/reject a connection request.

Question 9: What is the subnet address if the destination IP address is 144.16.34.124 and the subnet mask is 255.255.240.0?

• Answer: b. 144.16.34.0
• Explanation: With a subnet mask of 255.255.240.0 (or /20), the subnet address for the given IP falls in the range of 144.16.32.0 - 144.16.47.255. Thus, the correct subnet address is 144.16.32.0.

Question 10: An organization is allotted an address block with beginning address as 144.16.192.24/29 in CIDR notation. What will be the address range for that block?

• Answer: d. 144.16.192.24 to 144.16.192.31
• Explanation: A /29 subnet allows for 8 IP addresses, from 144.16.192.24 to 144.16.192.31.