Can anyone please help me in indentifying the problem when DP, MP & SUP goes down. Like sequence of log files which needs to be checked and the purpose of each log file in detail. Thanks in advance!!!

All ConfigMgr log files are here http://technet.microsoft.com/en-us/library/bb892800.aspx Also this link about ConfigMgr troubleshooting http://technet.microsoft.com/en-us/library/bb632812.aspx

In the same way, can you please help me in finding out the important log files which are required for DP,MP and SUP troubleshooting. All log files are important and none of them can be ignored, you should just know what needed logs for each troubleshooting case. Also, note that everyone must working several years and troubleshoot a lot of problems to build a good experience and playing with logs perfectly. So to answer you, I recommend you see again the log files link and you will find all that you need and classed per category (Management Point log files, Software Update Point log files, ...)