ccna security pdf

ccna security pdf.Table 7.2 Routing Table ExampleChapter 7 VLSM 151In the routing table above, entry 1 does not match because its subnet mask indicates that it is a host address (a 32-bit subnet mask). When comparing all 32 bits of 172.16.17.66 with 172.16.17.65, they do not match. Normally, whenever a host is moved from one network segment to another, but must retain its original address, a host address route needs to be added to the routing table.When comparing with entry 2 in the routing table, the router compares the first 27 bits of 172.16.17.64 and 172.16.17.65 and finds that they match. When comparing with entry 3, the router compares the first 24 bits of 172.16.17.0 and 172.16.17.64, and they also match. When comparing with entry 4, the router compares the first 16 bits of 172.16.0.0 and 172.16.17.65, and they also match.When compared with entry 5, the router finds that this is a default route that matches any packet. In this example, the first entry does not match, but the other 4 entries do. The router needs to select one of these entries and use it to route the packet to its destination. The router selects the entry with the highest degree of match-the entry with the most matching bits-so the router will use entry 2 in the routing table to route the packet to the destination.Routers from many vendors, including Cisco, allow the same destination network to be included in the routing table multiple times a if there are multiple paths to this destination network. For example, when going from Router A to 192.168.1.0/24, it may go through Router B, or through Router C. In this case, Router A's routing table will contain two entries for 192.168.1.0/24. When there are multiple paths to the same destination network in the routing table, different paths can be used to carry traffic of different protocols, thus enabling load sharing. For example, for traffic sent from host A to (located in 192.168.1.0/24) host B, it is always routed to the same next-hop neighbor, such as router B. (Load sharing is not recommended because it can cause problems for security devices such as firewalls.) oExam Key PointsKeep in mind how to select the correct entry from the routing table based on the destination IP address: the router will use the destination address that matches theentry with the most bits. Equal overhead load balancing supports the inclusion of multiple paths to the same destination network in the routing table, and also supportssupport for splitting traffic between multiple paths.