ccna security 640-554 pdf free download

ccna security 640-554 pdf free download.At this point, one more subnet is left. You can assign it to the last segment, but this segment requires only 30 host addresses, and subnet mask/26 provides 62 host addresses, so it is not optimal. If you wish, you can go back to step 4 and repeat the subnetting process for this subnet. Subnet Mask/27 ( 255.255.255.224) gives 30 host addresses to the subnet and further divides the remaining subnet 192.168.1.192/26 into two subnets: 192.168.1.192/27 and 192.168.1.224/27. In this example, there is one remaining subnet that can be used to support future expansion! As you can see, a very efficient IP addressing design can be developed using VLSM.Space should be reserved for expansion of each subnet. For example, in the previous example, using subnet mask/27 in subnet 192.168.1.192/26 would further divide it into two subnets, each containing 30 host addresses. With this addressing scheme, when a segment containing 30 hosts needs to be expanded, a portion of the network must be readdressed, which is not an interesting task.Exam Essentials Keep in mind the 6 steps for performing VLSM and read the next two VLSM examples in detail.1. VLSM Example 1Once you understand the basic steps for performing VLSM, look at a more complex example, as shown in Figure 7.2. In this example, given a Class C network 192.168.2.0/24, your task is to use VLSM to meet the following requirements: no more than 30 hosts in each remote site (seven in total), although this does not take into account future expansion; the links between the central site router and the remote site routers are point-to-point connections.The largest segments need to be handled first, and they are the remote sites containing 30 hosts. To provide 30 host addresses, the subnet mask 225.255.255.224 (/27) needs to be used, which will create the following subnets: 192.168 20/27, 192.168 232/27, 192.168.2.64/27, 192.168.2.96/27, 192.168.2.128/27, 192.168.2.160/27, 192.168.2.160/27. 192.168.2.160/27, 192.168.2.192/27, and 192.168.2.224/27. Subnet 0 is assumed to be available here.Remote Router A 30 hostsRemote Router B 30 hostsRemote router C 30 hostsTwo hosts Remote router D Central router 30 hosts