ccna 1 final exam quizlet

ccna 1 final exam quizlet.3. Troubleshooting Layer 3 ProblemsThis chapter suggests that the best starting point for troubleshooting serial links is to ping the IP address of the router on the other end of the link, specifically the IP address on the serial link. Interestingly, the serial link may be in the "up and knocking" state, but the ping will still fail due to a misconfiguration at Layer 3. In some cases, ping may work, but the routing protocol may not be able to exchange routes. This section briefly analyzes the failure phenomena and root causes, which may vary slightly depending on whether HDLC or PPP is used.First assume that there is an HDLC link with both the physical and data link layers operating normally. In this case, the interfaces of both routers are in the "up and up" state. However, if the IP addresses configured on the serial interfaces of the two routers belong to different subnets, pinging the IP address on the other end of the link will fail because the routers do not match the route. For example, as shown in Figure 12-17, if R1's serial IP address is still 192.168.2.1 and R2's is 192.168.3.2 (instead of 192.168.2.2) and the subnet mask is still /24, then both routers will have direct routes to different subnets, but neither will have a route that matches the other router's serial IP address.Finding and fixing the mismatched subnet problem is relatively simple using HDLC links. The usual first step for users is to ping the other end of the link11.3 Exam Prep 267 IP address, and if the result fails the problem is found. If both router interfaces have both interface status codes up, then the problem is most likely this mismatched IP subnet. For a PPP link with the same IP address/mask misconfiguration, pinging the IP address of the other router succeeds. However, the IP subnet mismatch still organizes the establishment of EIGRP and OSPF neighbor relationships, so it is still a good idea to follow the rules and set the IP addresses of both serial interfaces to IP addresses within the same subnet. PPP makes the ping command available by adding a host route (with a /32 prefix length) to the other router. This is part of the IPControlProtocol. Example 12-9 illustrates this scenario above. Tip: A route with a /32 prefix represents a single host and is called a HostRoute.Example 12-9 PPP permit pings successfully on a serial link even if there is a subnet mismatchRl# show ip route !Legend omitted for brevity-192 .168.1.0/24 is variably subnetted, 2 subnets, 2masks 192.168.1.0/24is directly connected, GigabitEthernet0/0 L 192.168.1.1/32 is directly connected, GigabitEtherne10/0192.168.2.0/24 is variably subnetted, 2subnets, 2masksC 192.168.2.0/24 is directly connected, SerialO/0/0