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Developing a Troubleshooting Checklist phần 2

By just telnetting to TCP port 80 and typing GET / HTTP/1.0 and then pressing Enter a few times, I can retrieve the default web page for the server | By just telnetting to TCP port 80 and typing GET HTTP 1.0 and then pressing Enter a few times I can retrieve the default web page for the server which at least verifies that the target host is properly connected to and communicating with the network and at best will tell me exactly what web server software is being run as shown on the 5th line from end Server Microsoft-IIS 6.0. Step3 Physically Check the Firewall One of the most common failures on a network is a physical failure. From bumped power cords to incorrectly seated network cables you can often quickly identify and remedy the problem by paying a visit to the physical machine. In addition many network devices including firewalls provide visual indicators regarding the status of the system. For example if you do not see a link light on an interface that is usually a good indicator that the network cable is not plugged in. In some cases for example remote firewalls it is just not feasible to check the firewall yourself. If you have a trusted person at that remote site however you can ask that person to check on the firewall on your behalf. As firewall administrators many of us have gotten used to being able to do most of our work remotely from our desk. As much of an annoyance as it may be to have to walk over to where the firewall is to check on it that pales in comparison to spending time trying to troubleshoot a connectivity problem only to find that someone bumped the power cord on the firewall. Step4 Check for Recent Changes Recent changes are not always responsible for problems that occur but they should always be examined as a potential cause of the problems. The reason for this is simple Today s networks are so complex that it is difficult to ensure that a change does not cause a problem for a dependent system. Consequentially it is critical that you have a means of tracking and monitoring the changes that are made in your environment so that you have something that you can refer back to. Good change