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.debug arp Displays information on ARP transactions.debug ip packet Displays general IP debugging information.debug ip icmp Displays information on Internet ControlMessage Protocol (ICMP) transactions andallows you to monitor the ICMP messages sentand received by your router.debug ip rip [events] Displays information on RIP routingtransactions.You may specify the eventsoptional keyword if you are only interested inseeing RIP protocol events.debug ip igrp events [ip-address] Displays summary information on sent andreceived Interior Gateway Routing Protocol(IGRP) routing messages.If you specify the IPaddress (optional) of a neighbor router (IGRPpeer), IGRP event debugging will be turned ononly for the address specified, plus any updatesthat the router broadcasts toward that neighbor.debug ip igrp transactions [ip-address] Displays information on IGRP routingtransactions.debug ip eigrp Displays the Enhanced IGRP packets sent andreceived on your router interfaces.debug ip ospf options Displays the OSPF packets sent and receivedby your router.The debug ip ospf commandmust be used with one of the following options:adj, events, flood, lsa-generation, packet,retransmission, spf, or tree.show debugging Displays the types of debugging that areenabled for your router. Foundation Summary 183Table 5-2 Important TCP/IP Commands Available from Windows NT (version 4.0) CMD Window PromptCommand Descriptionarp [options] Displays and modifies the IP-to-physical-address translation tables used by ARP.Ipconfig [options] Displays IP configuration information.Can beused with /renew and /release switches torenew and release DHCP-assigned parameters.The /all switch causes the complete IPinformation set to be displayed.Nbtstat [options] Displays protocol statistics and current TCP/IPconnections using NBT (NetBIOS over TCP/IP).route [options] Manipulates the local host s routing table.tracert [options] Performs a TCP/IP trace operation.Table 5-3 Typical TCP/IP Symptoms and Possible CausesSymptom Possible CauseHost cannot access remote hosts through Wrong default gateway or subnet maskrouter(s).configured on host.Router(s) between hosts are down ormisconfigured.Certain remote networks are not reachable from Access list(s).the local host.The local router doesn t have routes to thosenetworks (a routing issue).The remote host(s) or router(s) don t have aroute back to the local network/host.A major network is fragmented (discontinuous)and the protocols in use are not classless (orbad summarizations are performed).Users can access some hosts, but not others.Access list(s).Remote host s default gateway misconfigured.Not all remote services are available to local Extended access list(s).host(s).The remote service is not available.Routing tables are faulty after redistribution Metric parameter (or default metric) were notbetween protocols were configured.used for redistribution.Routing loops are also possible. 184 Chapter 5: Diagnosing and Correcting Campus TCP/IP ProblemsQ&AThe answers to the following questions can be found in Appendix A.Some of the questionsin this section are repeated from the Do I Know This Already Quiz so that you can gaugethe advancement of your knowledge of this subject matter.1 Name the main TCP/IP tool used for reachability testing.______________________________________________________________________________________________________________________________________________________________________________________________________2 Name the main TCP/IP tool used for path discovery between IP nodes.Also specifythe full Cisco IOS command for this tool.______________________________________________________________________________________________________________________________________________________________________________________________________3 Can the extended ping and trace be used from the user exec mode?______________________________________________________________________________________________________________________________________________________________________________________________________4 What is the IP path discovery command available with Microsoft s Windows 95 andWindows NT TCP/IP stack?______________________________________________________________________________________________________________________________________________________________________________________________________5 Name two Cisco IOS commands that allow you to see the IP address and subnet maskconfigured on a router s ethernet 0 interface (not a command that displays a router sstartup or running configuration).______________________________________________________________________________________________________________________________________________________________________________________________________ Q&A 1856 Specify the Cisco IOS command that allows you to see if an IP inbound access list isapplied to a router s ethernet 0 interface (not a command that displays a router sstartup or running configuration)._________________________________________________________________________________________________________________________________________________________________________________________________________7 Name the Cisco IOS command that allows you to see if IP Proxy-ARP is enabled/disabled on a router s ethernet 0 interface (not a command that displays a router sstartup or running configuration)
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