ANSWERS MUST BE EXPLAINED BRIEFLY

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Question 1: Host A with IP address 90.100.100.100 and MAC address AB:AB:AB:AB:AB:AB sends a packet to a Host B located in the internet. The IP address and MAC address of Host B are 10.10.10.8 and CC:CC:CC:CC:CC:CC, respectively. The default gateway of host A is router R1 which is further connected to the router of the ISP (R_ISP). Note that Ri has one interface connected to Host A and another interface connected to R_ISP. The IP addresses and MAC addresses of all interfaces of R1 and R_ISP are shown in the figure below. IP Address: 100.10.10.1 MAC Address: BC:8C:BC:BC:BC:BC IP Address: 100.10.10.2 MAC Address: BB:BB:BB:BB:BB:BB R1 R_ISP Internet IP Address: 90.100.100.1 MAC Address: AA:AA:AA:AA:AA: AA Host B Host A IP Address: 90.100.100.100 MAC Address: AB:AB:AB:AB:AB:AB IP Address: 10.10.10.8 MAC Address: CC.CCCCCC.CC.CC a) In order to communicate with Host B, Host A sends a packet to R1. What are the source and destination IP addresses, and source and destination MAC addresses in the packet transmitted by the Host A to R1? (0.5*4 = 2 marks) b) The packet above (in part a) now traverses from R1 to R_ISP. What are the source and destination IP addresses, and source and destination MAC addresses now? (0.5*4 = 2 marks) Question 2: Answer the questions regarding the given topology. Router A and Router B have 50 PCs and 20 PCs connected to them, respectively. The IP address space given to you is 192.168.10.0/25. (8 marks) S/DID 50100 1841 Ryter A 1841 Router TT with 2940-ATT Switch PC.PT PC PC-PT PCI PC.PT PC2 PC.PT PCB 50 PCS 20 PC I. Write Subnet Mask, Network ID, Broadcast ID and host address range for Router A Subnet. You must clearly explain all the steps involved otherwise no marks will be given. (4 marks) II. Write Subnet Mask, Network ID, Broadcast ID and host address range for Router B Subnet. You must clearly explain all the steps involved otherwise no marks will be given. (4 marks) Question 3: What is a Distributed Denial of Service attack (DDoS)? Briefly explain the UDP Flood DDoS attack (1+2 = 3 marks)