Network drivers (bridge, host, overlay, none) in Docker - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the command to create a Docker container using the default network driver.

Docker

docker run --rm -it --network [1] alpine sh

Drag options to blanks, or click blank then click option'

Abridge

Bnone

Coverlay

Dhost

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'host' which uses the host's network directly.

The default Docker network driver is bridge. It creates a private internal network on the host.

2fill in blank

medium

Complete the command to run a container that shares the host's network stack.

Docker

docker run --rm -it --network [1] nginx

Drag options to blanks, or click blank then click option'

Aoverlay

Bnone

Chost

Dbridge

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'bridge' which isolates container network from host.

The host network driver makes the container use the host's network directly, without isolation.

3fill in blank

hard

Fix the error in the command to create a multi-host Docker network.

Docker

docker network create -d [1] mynet

Drag options to blanks, or click blank then click option'

Ahost

Boverlay

Cbridge

Dnone

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'bridge' which works only on a single host.

The overlay driver allows containers on different Docker hosts to communicate securely.

4fill in blank

hard

Fill both blanks to create a container with no network access.

Docker

docker run --rm -it --network [1] alpine sh -c "ping [2]"

Drag options to blanks, or click blank then click option'

Anone

B127.0.0.1

Cgoogle.com

Dbridge

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'bridge' network which allows external access.

The none network driver disables networking for the container. Pinging 127.0.0.1 tests localhost inside the container.

5fill in blank

hard

Fill all three blanks to create an overlay network and run a container attached to it.

Docker

docker network create -d [1] my_overlay_net && docker run --rm -it --network [2] alpine sh -c "ip addr show [3]"

Drag options to blanks, or click blank then click option'

Aoverlay

Bmy_overlay_net

Ceth0

Dbridge

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'bridge' driver for multi-host network.

Create an overlay network named my_overlay_net. Then run a container attached to that network and show the IP address of interface eth0.

Practice

1. Which Docker network driver allows containers on the same host to communicate using a private internal network?

easy

A. bridge

B. host

C. overlay

D. none

Solution

1. Step 1: Understand the purpose of the bridge driver

   The bridge driver creates a private network internal to the host, allowing containers to communicate securely on the same machine.

2. Step 2: Compare with other drivers

   The host driver uses the host's network directly, overlay connects containers across hosts, and none disables networking.

3. Final Answer:

   bridge -> Option A

4. Quick Check:

   Private internal network = bridge [OK]

Hint: Bridge = private network on one host [OK]

Common Mistakes:

• Confusing host with bridge driver
• Thinking overlay works on single host only
• Assuming none allows communication

2. Which command correctly creates a Docker container using the host network driver?

easy

A. docker run --network=bridge nginx

B. docker run --net=overlay nginx

C. docker run --network=host nginx

D. docker run --network=none nginx

Solution

1. Step 1: Identify the correct syntax for network option

   The correct flag is --network= followed by the driver name, e.g., host.

2. Step 2: Match the driver to the command

   docker run --network=host nginx uses --network=host which is the correct way to assign the host network driver.

3. Final Answer:

   docker run --network=host nginx -> Option C

4. Quick Check:

   Use --network=host for host driver [OK]

Hint: Use --network=host to assign host driver [OK]

Common Mistakes:

• Using --net=overlay instead of --network=overlay
• Confusing bridge and host flags
• Omitting the network flag

3. Given two Docker hosts connected with an overlay network named mynet, what will happen if you run docker network inspect mynet on one host?

medium

A. It shows no containers because overlay networks isolate containers

B. It shows only local bridge network details

C. It returns an error because overlay networks can't be inspected

D. It shows details of the overlay network including connected containers across hosts

Solution

1. Step 1: Understand overlay network scope

   Overlay networks span multiple Docker hosts, connecting containers across them.

2. Step 2: Inspect command behavior

   docker network inspect shows detailed info about the network, including containers connected on all hosts.

3. Final Answer:

   It shows details of the overlay network including connected containers across hosts -> Option D

4. Quick Check:

   Overlay network inspect shows multi-host details [OK]

Hint: Overlay networks span hosts; inspect shows all connected containers [OK]

Common Mistakes:

• Thinking overlay networks can't be inspected
• Assuming inspect shows only local containers
• Confusing overlay with none driver

4. You created a container with --network=none but it still can ping the host. What is the likely cause?

medium

A. The container has another network interface configured manually

B. The none driver allows all network traffic by default

C. Docker daemon is ignoring the network flag

D. The container is running in host network mode

Solution

1. Step 1: Understand the none network driver

   The none driver disables Docker-managed networking, so no automatic network interfaces are created.

2. Step 2: Analyze why container can ping host

   If the container can ping the host, it likely has a manually configured network interface inside the container.

3. Final Answer:

   The container has another network interface configured manually -> Option A

4. Quick Check:

   none disables Docker network; manual config allows connectivity [OK]

Hint: none disables Docker network; manual setup can override [OK]

Common Mistakes:

• Assuming none allows all traffic
• Thinking Docker ignores network flags
• Confusing none with host driver

5. You want to deploy a multi-host Docker Swarm service where containers communicate securely across hosts. Which network driver should you use and why?

hard

A. bridge, because it isolates containers on each host

B. overlay, because it connects containers across multiple hosts securely

C. host, because it uses the host network for better performance

D. none, because it disables networking for security

Solution

1. Step 1: Identify network needs for multi-host communication

   Containers on different hosts need a network driver that spans hosts and provides secure communication.

2. Step 2: Match drivers to requirements

   Bridge works only on one host, host shares host network (not multi-host), none disables networking, overlay connects containers across hosts securely.

3. Final Answer:

   overlay, because it connects containers across multiple hosts securely -> Option B

4. Quick Check:

   Multi-host secure communication = overlay [OK]

Hint: Overlay = multi-host secure network [OK]

Common Mistakes:

• Choosing bridge for multi-host
• Using host driver for container isolation
• Thinking none enables communication