Docker Networks Explained: Bridge, Host, None, Custom Networks and Port Mapping

Docker Networks Explained#

Docker networks allow containers to communicate with each other, the host, and external systems. This guide explains bridge networks, host network, custom networks, DNS, and port publishing.

Quick answer#

• Network — Use case
• bridge — Default single-host container networking.
• custom bridge — Recommended for app containers that need DNS-based communication.
• host — Container shares host network stack.
• none — No network access.

List networks#

docker network ls

Create a custom network#

docker network create app_net

Run containers on the same network#

docker run -d --name redis --network app_net redis:7 docker run -it --rm --network app_net alpine sh

Inside the Alpine container, you can reach Redis using the container name redis .

apk add --no-cache redis redis-cli -h redis ping

Port mapping#

Port mapping exposes a container port on the host machine.

docker run -d --name web -p 8080:80 nginx

Here, host port 8080 maps to container port 80 .

Inspect a network#

docker network inspect app_net

Connect and disconnect containers#

docker network connect app_net web docker network disconnect app_net web

Common networking problems#

• Problem — Likely cause — Fix
• Cannot access app from browser — Port not published — Use -p HOST:CONTAINER .
• Containers cannot resolve names — Not on same custom network — Use a custom network.
• Port already allocated — Host port already in use — Choose another host port.

Best practices#

• Use custom bridge networks for related containers.
• Expose only required ports.
• Use container names or Compose service names for internal communication.
• Avoid host network unless you really need it.
• Document port mappings clearly.

Related Melochip guides#

• Docker Learning Path
• Docker Compose Beginner Guide
• Kubernetes Cluster Setup Guide

Official references#

• Docker networking documentation