ccna 200 301 easy exam

ccna 200 301 easy exam.To summarize, the host cannot ping its default router, and vice versa. With this initial symptom in mind, the question is: What could be causing this symptom? For example, in Figure 16-14, what would prevent host B from pinging router R3, especially after removing the host and router IPv6 settings?Figure 16-14 Where to Look for Problems Based on Router LAN Interface StatusTo identify the problem, the engineer must begin to consider the world outside the scope of IPv6, the LAN between the host and the router. specifically, the most likely causes can be categorized as follows. , /speech (1) The router or host LAN interface is administratively disabled. I calyx rape (2) There is some problem with the LAN that prevents the flow of outbound frames.(3) Some filtering of the LAN (e.g., port security) is blocking out Ethernet frames.First, routers and hosts can be told to stop using a particular interface. There is no doubt that the router can use the shutdown interface subcommand. If G0/1 of R3 is shut down at this point, then the engineer will see the ping results described in this scenario. The host is also capable of shutting down and booting its own interface, which will again cause these same ping symptoms. So what's the solution? Use the noshutdown command on the router, or enable the interface on the host.For the second problem on the list, the LAN issue was discussed in detail in Part 1 of this book. However, as a troubleshooting tip, note that if R3's G0/1 interface is down/down, then a LAN problem may exist on one of the network links directly connected to the R3G0/1 interface. However, if R3's G0/1 is up/up, then a LAN problem may exist elsewhere on the LAN itself. If the ping still does not work, review Chapter 3, "Troubleshooting LAN Switching".For the third problem in the list, it is possible that some filtering mechanism (such as port security) is intentionally screening out frames sent by the host (B) or router (R3G0/1). In addition, router R3 may have received an inbound IPv6ACL on its G0/1 interface, and unfortunately, it is this connection that is being used to filter out frames from host (B) or router (R3G0/1).16.2 Base Content Port 343 filters out inbound ICMPv6 packets, thus causing it to drop incoming packets generated by the ping command. Any issues that require the use of DNS functionality Now we move on to the third unique troubleshooting scenario, where our engineers are troubleshooting Host C. A ping from Host C to Server 1,by host name, fails, however, pinging Server 1's IPv6 address is valid. The engineer tried another similar test, pinging another server (Server 2), with the same result: pinging by host name failed, while pinging the IPv6 address was fine. These symptoms are a clear indication of "some kind of name resolution problem". However, this does not yet identify a specific root cause that the engineer can fix to get the user working again. In this case, the root cause can be grouped into the following categories. 'Tasting Volumes (1) Incorrect host DNS server settings, as statically defined on the host.' Tam mi (2) Incorrect host DNS server settings, as learned by using (stateless or by-state) DHCPv6. (3) IPv6 connectivity issues between the user host and the DNS server. For the first reason listed above, if the host's DNS server settings are incorrect, then the host sends DNS requests to the wrong destination address. The result is that the host cannot get a DNS response and is not informed of the IPv6 address of the destination host. So what is causing this? Someone entered the wrong information into the host IPv6 configuration settings. The second cause listed in the list is similar to the first, but is also somewhat different and is thus separated into a second category. The user's computer does not have the correct DNS server settings, but IPv6 is informed of the settings using DHCPV6. Basically, the symptoms are the same, but the causes are different. It is important to note that hosts can use DHCPv6 to learn DNS addresses regardless of stateful DHCPv6 and SLAAC. The third cause requires a little additional discussion and an example. The example shows Host C in Figure 16-15, with a two-step process. This process occurs when the host first uses the pingServerl command to test Server1. First, the IPv6 packets must flow from C to the DNS server and then back again for name resolution. In step 2 of the figure. the IPv6 packets can flow to Serverl's IPv6 address. Depending on the topology in the cloud, connectivity issues may exist between host C and the DNS server, otherwise there are no such issues between C and Serverl. Therefore, when the symptoms of the problem point to something like "name resolution not working", but the host appears to be pointing to the correct DNS server address, start checking the underlying IPv6 connection between the host and the DNS server.Figure 16-15 DNS name resolution before forwarding packets to the serverHost lost IPv6 settings: stateful DHCP problem Now let's flip to a whole new scenario. Our network engineers are now troubleshooting a problem with a user, Host D. Work 344 Chapter 16 Troubleshooting IPv6 Routing