Troubleshooting Speaker Saengsan Tinarak Channel Demo Inssider netstumbler

THE EIGHT STEPS The most important part of troubleshooting any problem is to divide the tasks of problem resolution into a systematic process of elimination. Cisco has broken this process into eight steps: 1. Define the problem. 2. Gather detailed information. 3. Consider probable cause for the failure. 4. Devise a plan to solve the problem. 5. Implement the plan. 6. Observe the results of the implementation. 7. Repeat the process if the plan does not resolve the problem. 8. Document the changes made to solve the problem. Channel Demo Inssider netstumbler

DEFINE THE PROBLEM AND GATHER FACTS How many times have you heard this: “My computer does not work”? Which leads us to the network administrator’s response: “Could you please be more vague?” Channel Demo Inssider netstumbler

Consider the possibilities After a problem has been identified, the next step is to consider all of the possible causes. Connectivity issues can be very difficult to trace to a single point of failure. In most situations, there are several possible causes for a network error, and the administrator should identify each probable cause.

CREATE AND IMPLEMENT AN ACTION PLAN Once the network problem and possible causes have been identified, it’s time to produce a solution. When developing a solution, it’s critical to thoroughly analyze the proposed solution and brainstorm with your peers the potential impacts your solution may have.

CREATE AND IMPLEMENT AN ACTION PLAN Here are a few of the most important guidelines to follow when implementing a solution: Make one change at a time. Make transparent changes first. This means if there are multiple possible causes for a problem, solve those problems that have the least impact on your users first. Do not create security holes when implementing your changes. Finally, and most importantly, always be sure you can back out of any changes you make.

OBSERVE THE RESULTS Observe results and, if necessary, try another solution Some changes may take time to trigger. Observe the results of your solution. Go back to the fact-gathering phase and determine if your solution solved the problem. If the trouble still exists, reference your list of possible causes and attempt to resolve the next most likely cause of the problem.

TROUBLESHOOTING TOOLS Ipconfig Ping Tracert Pathping Nslookup Netstat ARP Channel Demo Inssider netstumbler

IPCONFIG Displays all current Transmission Control Protocol/Internet Protocol (TCP/IP) network configuration values, and refreshes Dynamic Host Configuration Protocol (DHCP) and DNS settings. ipconfig /? ipconfig /flushdns

PING Ping Command Syntax ping [-t] [-a] [-n count] [-l size] [-f] [-i TTL] [-vTOS] [-r count] [-s count] [-w timeout] [-R] [-S srcaddr] [-4] [-6] target [/?]

TRACERT The tracert command is a Command Prompt command that's used to show several details about the path that a packet takes from the computer or device you're on to whatever destination you specify. Tracert Command Syntax tracert [-d] [-h MaxHops] [-w TimeOut] [-4] [-6] target [/?]

PATHPING Combines the functions of Traceroute and Ping to identify problems at a router or network link. The pathping command functions much like the tracert command but will also report information about network latency and loss at each hop.

NSLOOKUP nslookup is a network utility program used to obtain information about Internet servers. As its name suggests, the utility finds name server information for domains by querying C:\>nslookup Default Server: caching-dns1.rmutp.ac.th Address: 202.29.104.2

NETSTAT The netstat command is a Command Prompt command used to display very detailed information about how your computer is communicating with other computers or network devices. Specifically, the netstat command can show details about individual network connections, overall and protocol-specific networking statistics, and much more, all of which could help troubleshoot certain kinds of networking issues. Netstat Command Syntax netstat [-a] [-b] [-e] [-f] [-n] [-o] [-p protocol] [-r] [-s] [-t] [-x] [-y] [time_interval] [/?]

ARP converts an Internet Protocol (IP) address to its corresponding physical network address.