Docker Networking (Null Network, None Network)

none network in docker means when you don't want any network interface for your container. If you want to completely disable the networking on a container, you can use the --network none flag when starting the container. Within the container, only the loopback device is created. 

Create a container with network type as ‘null’-

gaurav@learning-ocean:~$ docker container run -it --network none ubuntu:14.04 bash

Now check the network configuration of this container with ifconfig command-

root@0e26891303d0:/# ifconfig
lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
root@0e26891303d0:/#

So a null type of network is used when the container is not a part of any network and is isolated in all aspects.