Docker Bridge

The bridge driver creates a private network for containers on the host machine. When you start Docker, it automatically creates a default bridge network on the host machine, represented by a virtual interface (docker0), which started containers connect to unless otherwise specified. Containers on the same bridge network can talk to each other via IP addresses. However, if you want to access a service (like a webserver) running in a container from your host machine, you'll need to expose ports to the host.

User Defined Custom Bridge

Uses the same bridge driver, but you define it instead. There are some advantages to using this type of network:

• It provides automatic DNS resolution between containers, which means that containers can resolve each other by name or alias.
• User Defined Bridges provide better isolation. Only containers connected to the same user-defined bridge can communicate with each other.

Create a user-defined bridge

docker network create custombridge

Create a container connected to the user-defined bridge

docker run -itd --rm --network custombridge alpine