Grade+12+Course+Sept.+19th++to+Sept.+24th

__Level 1 Help Desk:__ __Le____vel 2 Help Desk:__ __Level 3 Help Desk:__
 * __Sept. 19th 2011:__**

__**Tuesday Sept. 20th 2011:**__ - Hubs work on Layer 1, switches on Layers 1 and 2, routers on Layers 1, 2 and 3, and firewalls on Layers 1, 2, 3, and 4.










 * __Wednesday Sept. 21st 2011:__**

The OSI model also provides a systematic basis for troubleshooting a network. In any troubleshooting scenario, the basic problem-solving procedure includes the following steps: 1. Define the problem. 2. Isolate the cause of the problem. 3. Solve the problem. Identify and prioritize alternative solutions.Select one alternative as the solution.Implement the solution.Evaluate the solution.

Bottom-Up - The bottom-up approach starts with the physical components of the network and works its way up the layers of the OSI model. Bottom-up troubleshooting is an effective and efficient approach for suspected physical problems. Top-Down - The top-down approach starts with the user application and works its way down the layers of the OSI model. This approach starts with the assumption that the problem is with the application and not the network infrastructure. Divide-and-Conquer - The divide-and-conquer approach is generally used by more experienced network technicians. The technician makes an educated guess targeting the problem layer and then based on the observed results, moves up or down the OSI layers. - At Layer 3, several utilities can assist with the troubleshooting process. Three of the most common command line tools are: ipconfig - Shows IP settings on the computer ping - Tests basic network connectivity tracert - Determines if the routing path between the source and destination is available



Today I read my cisco grade 12 course and here is all the important points In read today:
 * __Thursday Sept. 22nd:__**