Clarify the key difference: "Custom bridge networks give automatic DNS — containers find each other by name. The default bridge does not. I always create a named network in Compose rather than relying on the default."
Bridge (default): creates a private network on the host. Containers on the same bridge can communicate by container name (DNS resolution via embedded DNS server). Exposed ports are mapped to the host with -p. Host: container shares the host network namespace directly — no isolation but no port mapping overhead. Overlay: spans multiple Docker hosts for Swarm or multi-node setups. Containers communicate via virtual networks. Key concepts: each bridge gets a subnet, containers get IP addresses, port publishing (host:container mapping), and custom bridge networks provide automatic DNS resolution (the default bridge does not). Strong candidates discuss: using custom networks for service isolation, the difference between expose and publish, container-to-container communication within Compose, and DNS-based service discovery.
Tests understanding of container networking. Candidates who only use port mapping without understanding bridge networks will struggle with multi-container setups. Those who understand DNS resolution and network isolation can design proper service architectures.