Docker Networking Fundamentals and Host Differences
📌 Docker networking facilitates communication between containers on the same host and across different hosts, covering drivers like bridge, host, overlay, and others.
💻 Local development on macOS/Windows requires port forwarding to access containers via `localhost`, as direct IP access is unavailable due to Docker running inside a virtual machine.
☁️ For optimal Docker networking features, Linux is required; features often used for remote/production setups are less effective on Mac/Windows development environments.
⚠️ Kubernetes overhead is significant for simple applications; avoid it unless necessary, as Docker on a single Linux server is often sufficient for 3-tier apps.

Bridge Network Driver (Default vs. User-Defined)
🌉 The default bridge network connects the host and a Docker-created virtual network (e.g., CIDR `172.17.0.0/16`), allowing inter-container communication.
❌ Docker does not recommend using the default bridge network, particularly in production, due to limitations.
🔑 User-defined bridge networks are recommended because they enable DNS resolution between containers using their assigned container names (e.g., `myapp`), which is not possible on the default bridge.

Host Network Driver
🌐 The `host` driver removes networking isolation, making the container share the host's networking namespace and IP address.
⚡ This mode avoids Network Address Translation (NAT) and `userland-proxy` creation, leading to increased performance.
🚫 It is unsuitable for local development if multiple containers need to bind to the same port (e.g., running two proxies on port 80).

None Network Driver
⛔ The `none` network driver completely isolates the container, creating only a loopback interface (`lo`).
⚙️ This mode is best suited for batch jobs or data processing pipelines where external connectivity is not required.

IPvlan Network Driver
🔗 IPvlan is lightweight as it avoids using a bridge and associates directly with the host's Linux network interface.
🏠 Containers receive an IP address from the same host CIDR range (e.g., if host is `192.168.50.55/24`, container gets an IP in that range).
📡 This allows external services to access the container directly via its assigned IP without port mappings.
⚠️ Unlike `macvlan`, containers using `ipvlan` receive the same MAC address as the host.

Macvlan Network Driver
🔌 `macvlan` assigns a unique MAC address to the container's virtual interface, making it appear as a physical interface on the network.
💻 This is crucial for legacy applications or those monitoring network traffic that expect direct physical network connection.

Overlay Network Driver
🌐 The `overlay` network driver creates a distributed network across multiple Docker daemon hosts (servers).
🛡️ It allows secure communication between containers across different hosts, often used with Docker Swarm, especially when encryption is enabled.
🛠️ To connect individual containers (not just Swarm services) to an overlay network, the Docker Swarm must be initialized and the network created with the `attachable` flag.

Key Points & Insights
➡️ For container-to-container communication locally, always create a user-defined bridge network to utilize container name resolution via DNS.
➡️ Use the `host` network driver in production when performance optimization or binding to many host ports is critical, provided you are on Linux.
➡️ Use the `none` network driver when running containers that must be completely isolated from the host network for security or specific processing tasks.
➡️ For multi-host communication, the `overlay` network provides secure, distributed connectivity, requiring Docker Swarm initialization for individual container use.

📸 Video summarized with SummaryTube.com on Dec 29, 2025, 11:27 UTC