Docker - Networking - Default Docker Networks

When Docker is installed, it automatically creates a few default networks:

Bridge: The default network for containers.
- If no network is specified when creating a container, Docker places it in the bridge network.
- The default network type for containers on standalone hosts.
- Containers on the same bridge network can communicate with each other via IP addresses, and you can also map container ports to the host system.
Host: Bypasses Docker’s virtualized network stack and allows the container to use the host’s network directly.
- This network mode allows a container to share the host system’s network stack.
- No isolation between the container and the host network.
None: Containers are isolated with no network interface, perfect for processes that do not need network connectivity.

Docker - Networking - The default network

Every clean installation of Docker comes with a pre-built network called bridge.

docker network ls

returns:

NETWORK ID     NAME      DRIVER    SCOPE
45df8a26c099   bridge    bridge    local
99d0975ea463   host      host      local
0190ffd8ff93   none      null      local

NOTE: The bridge network is associated with the bridge driver.

It is important to note that the network and the driver are connected, but they are not the same.
- In this example the network and the driver have the same name - but they are not the same thing!

The output above also shows that the bridge network is scoped locally.
- This means that the network only exists on this Docker host.
- This is true of all networks using the bridge driver - the bridge driver provides single-host networking.

All networks created with the bridge driver are based on a Linux bridge (a.k.a. a virtual switch).