Apache Access日志收到请求时间问题

请在Ubuntu 14.04的Apache(2.4.7)访问日志中查看接收到请求时间的奇怪情况:

IP1 - - [14/Dec/2016:00:00:02 +0300] "GET /portal/get.php?filename=file1.mpg HTTP/1.1" 206 194292 "-" "Lavf53.32.100" IP1 - - [14/Dec/2016:00:00:02 +0300] "GET /portal/get.php?filename=file1.mpg HTTP/1.1" 206 140716 "-" "Lavf53.32.100" IP1 - - [14/Dec/2016:00:00:02 +0300] "GET /portal/get.php?filename=file1.mpg HTTP/1.1" 206 191396 "-" "Lavf53.32.100" IP2 - - [13/Dec/2016:23:59:59 +0300] "GET /portal/get.php?filename=file2.mpg HTTP/1.1" 206 6010910 "-" "Lavf53.32.100" IP2 - - [14/Dec/2016:00:00:03 +0300] "GET /portal/get.php?filename=file2.mpg HTTP/1.1" 206 189950 "-" "Lavf53.32.100" IP2 - - [14/Dec/2016:00:00:03 +0300] "GET /portal/get.php?filename=file2.mpg HTTP/1.1" 206 191398 "-" "Lavf53.32.100" IP2 - - [14/Dec/2016:00:00:03 +0300] "GET /portal/get.php?filename=file2.mpg HTTP/1.1" 206 237734 "-" "Lavf53.32.100" IP2 - - [14/Dec/2016:00:00:03 +0300] "GET /portal/get.php?filename=file2.mpg HTTP/1.1" 206 194294 "-" "Lavf53.32.100" IP3 - - [13/Dec/2016:23:59:34 +0300] "GET /portal/get.php?filename=file3.mpg HTTP/1.1" 206 5374262 "-" "Lavf53.32.100" IP1 - - [14/Dec/2016:00:00:02 +0300] "GET /portal/get.php?filename=file1.mpg HTTP/1.1" 206 5465012 "-" "Lavf53.32.100" IP1 - - [14/Dec/2016:00:00:06 +0300] "GET /portal/get.php?filename=file1.mpg HTTP/1.1" 206 184156 "-" "Lavf53.32.100" IP1 - - [14/Dec/2016:00:00:06 +0300] "GET /portal/get.php?filename=file1.mpg HTTP/1.1" 206 121892 "-" "Lavf53.32.100" 

任何想法为什么时间不安排升序?
这是一个Apache的问题,或者我的服务器有问题或者不用担心这个问题?
还有什么我需要检查服务器上?

日志中logging的时间是最初收到请求的时间。 但是,日志条目直到请求完成才真正写入。 因此,当一些请求需要更多时间来完成时,请求可能会出现乱序。