How Docker networking works by default
bridge network, docker0 interface, container IP assignment, default bridge, host network, none network, network isolation
Docker's Default Network Model
Every container gets a virtual network interface connected to a virtual bridge - docker0 by default. Docker assigns each container a private IP (typically in the 172.17.0.0/16 range). Containers on the same bridge can reach each other by IP.
Three Built-in Network Drivers
bridge (default): Containers connect to a virtual Ethernet bridge. Good for most use cases. Containers on the same custom bridge can resolve each other by container name.
host: The container uses the host's network stack directly. No port mapping needed, but no network isolation. Linux-only.
none: No networking. Container is fully isolated from all networks. Useful for pure compute tasks.
# Run using host network
docker run --network host nginx
# Run with no network
docker run --network none my-job
Container-to-Container Communication
On the default bridge, containers can reach each other by IP but not by name. DNS resolution only works on custom bridges, not the default one.
docker network ls # List all networks
docker network inspect bridge # See connected containers and their IPs