The document discusses the precedence order of the Hadoop configuration parameter "dfs.block.size" when defined in different configuration files and levels. It finds that: 1) When files are created via MapReduce, the master node configuration takes precedence over slave nodes, unless a slave sets "final=true", which overrides all other values. 2) When files are created via client utilities like "hadoop fs", the client configuration ("hdfs-site.xml") has highest precedence and overrides all other values, including those set to "final=true". 3) The default block size is 64MB, but the client can override this by specifying "-D dfs.block.size" on the command line.