During the execution of a task sequence, you can monitor the progress in real time by looking at the report titled “History – Specific task sequence advertisements run on a specific computer”.
Note: Replace SCCMSERVER for the name of your server with the reporting role.
You can also reach this report by starting with the report titled “Status summary of a specific task sequence advertisement” and then drilling down.
In addition to the web reports the build process also creates log files locally on the computer. These are excellent for detailed troubleshooting. They start out in a “_SMSTaskSequence” folder in the root of the largest partition, but end up in the standard ConfigMgr client logs folder (C:WindowsSystem32CCMLogs on a 32-bit OS and C:WindowsSysWOW64CCMLogs on a 64-bit OS). The main log file is smsts.log, but there is also BDD.log and various ZTI*.log.