Q: What are the different Docker Network Types?

Answer:

Docker provides several built-in network drivers. Understanding them is crucial for designing multi-container applications.

1. Bridge Network (Default)

The default network type for standalone containers. Docker creates a virtual bridge (docker0) on the host and assigns each container a private IP address within that bridge's subnet.

# Containers on the default bridge can communicate via IP, 
# but NOT by container name (no automatic DNS).
docker run -d --name app1 nginx
docker run -d --name app2 nginx
# app2 cannot reach app1 via http://app1 (only by IP)

# Custom bridge networks DO support DNS resolution:
docker network create mynet
docker run -d --name app1 --network mynet nginx
docker run -d --name app2 --network mynet nginx
# Now app2 CAN reach app1 via http://app1 ✅

[!IMPORTANT] Always use custom bridge networks instead of the default bridge. Custom bridges provide automatic DNS resolution, better isolation, and the ability to connect/disconnect containers dynamically.

2. Host Network

Removes network isolation entirely. The container shares the host's network stack directly. No port mapping is needed — the container's ports are the host's ports.

docker run --network host nginx
# nginx is now accessible on the host's port 80 directly

Pros: Best network performance (no NAT overhead). Cons: Port conflicts if multiple containers use the same port. Not available on Docker Desktop (macOS/Windows).

3. Overlay Network

Enables communication between containers running on different Docker hosts (across machines). Used in Docker Swarm and Kubernetes environments.

docker network create -d overlay my-overlay

Uses VXLAN tunneling under the hood to encapsulate container traffic across physical network boundaries.

4. None Network

Completely disables networking for the container. The container only has a loopback interface.

docker run --network none myapp
# No external network access at all

Use case: Security-sensitive batch processing where no network communication should be possible.

Summary