ccna routing question

ccna routing question.4. The subnet mask table for Class C networks 6.5 lists the valid subnet masks for Class C networks, where the number of network bits is the total number of bits in the network and subnet parts.Table 6.3 Valid subnet masks for Class A networksAs can be seen from Tables 6.3, 6.4 and 6.5, subnet masks are not chosen and used arbitrarily for classified networks: some subnet masks are valid for some classified networks, but not for others. For example, the subnet mask 255.255.0.0 is valid for Class A and Class B networks, but not for Class C networks.Table 6.4 Valid Subnet Masks for Class B NetworksTable 6.5 Valid subnet masks for Class C networksAuthentication Objectives 6.036.3 IP Address PlanningIn terms of addressing, protocols such as AppleTalk.IPX and XNS are easy to deal with: they all have different network sections and host sections. In these protocols, there are no subnet masks that can be used to modify the boundaries of the network part and the host part. When I was new to TCP/IP, understanding how to deal with subnetting and IP addressing became one of the trickiest tasks I faced in my networking career. To add insult to injury, IP addressing is based on binary math operations because that's how computing devices handle numbers. Considering that I, with a degree in mathematics, find IP addressing tricky, you can imagine how bizarre it is for the layman!However, with years of experience dealing with TCP/IP and teaching Cisco courses, I've come up with a simple six-step method that helps studentsPlan the IP addressing of the network. 1. Determine network and host requirements. 2. Meet host and network requirements. 3. Determine the subnet mask. 4. Determine network addresses. 5. determine the network's directed broadcast address. 6. determine the host addresses for the network. These 6 steps are covered in depth in the next few subsections.