我想了解使用Dockerfile构建Docker映像所涉及的执行步骤。我在下面列出了几个问题。请帮助我了解构建过程。

Dockerfile内容

#from base image
FROM ubuntu:14.04
#author name
MAINTAINER RAGHU
#commands to run in the container
RUN echo "hello Raghu"
RUN sleep 10
RUN echo "TASK COMPLETED"

用于生成映像的命令： docker build -t raghavendar/hands-on:2.0 .

Sending build context to Docker daemon 20.04 MB
Step 1 : FROM ubuntu:14.04
---> b1719e1db756
Step 2 : MAINTAINER RAGHU
---> Running in 532ed79e6d55
---> ea6184bb8ef5
Removing intermediate container 532ed79e6d55
Step 3 : RUN echo "hello Raghu"
---> Running in da327c9b871a
hello Raghu
---> f02ff92252e2
Removing intermediate container da327c9b871a
Step 4 : RUN sleep 10
---> Running in aa58dea59595
---> fe9e9648e969
Removing intermediate container aa58dea59595
Step 5 : RUN echo "TASK COMPLETED"
---> Running in 612adda45c52
TASK COMPLETED
---> 86c73954ea96
Removing intermediate container 612adda45c52
Successfully built 86c73954ea96

在步骤2中：

Step 2 : MAINTAINER RAGHU
    ---> Running in 532ed79e6d55

问题1：它表明它在ID为532ed79e6d55的容器中运行，但是此容器是用什么Docker映像形成的？

---> ea6184bb8ef5

问题2：这是什么ID？是图像还是容器？

Removing intermediate container 532ed79e6d55

问题3：是否从中间容器中保存了多层形成的最终图像？