2. (a) Briefly explain why collision detection is not used in IEEE 802.11 Wireless Local Area Network? (7 Marks (b) Assume that the header of an IP packet in the hexadecimal form is: 01 50 68 03 C4 25 F6 F7 00 00, where 00 00 is the checksum to be calculated. Compute the checksum using the binary approach. Show your final answer in hexadecimal number. 9 Marks) (c) You are a senior network manager of Merlion International Limited. Your company set up a subsidiary in Thailand recently. You have managed to secure a block of class C IP address 200.5.6.0 for the subsidiary. You designed the physical network and assigned a new engineering associate to do the IP network design You told the engineering associate that all the switch ports would be fully utilized He came up with the IP network design shown in Figure 2. Identify all the design errors and justify your answers. Make changes to the IP network design to rectifs all the design errors. (9 Marks 200.5.6.0 27 Router A Internet Gateway Router EDHE Switch 2: 8 ports Router B Router Switch 3: 16 ports 200.5.6.3227 Swich S port 2005.6.12527 Switch 1: 4 ports 200.5.664 27 200.5.6.9627 Switch 6:16 ports Router Switch 16 ports Figure 2