Inspecting container network settings in Docker - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the command to list all Docker networks.

Docker

docker network [1]

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

Acreate

Brm

Cls

Dinspect

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'create' instead of 'ls' will try to make a new network.

Using 'rm' will delete a network, not list it.

The docker network ls command lists all Docker networks on your system.

2fill in blank

medium

Complete the command to inspect the network named 'bridge'.

Docker

docker network [1] bridge

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

Ainspect

Bcreate

Cls

Drm

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'ls' lists networks but does not show details.

Using 'rm' deletes the network.

The docker network inspect command shows detailed information about a specific network.

3fill in blank

hard

Fix the error in the command to inspect a container's network settings by container ID 'abc123'.

Docker

docker container [1] abc123

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

Als

Binspect

Crm

Dstart

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'ls' lists containers but no details.

Using 'rm' deletes the container.

The correct command to see detailed info about a container, including network settings, is docker container inspect.

4fill in blank

hard

Fill both blanks to complete the command that filters network inspect output to show only the container's IP address.

Docker

docker network inspect bridge --format '{{{{.Containers.[1].[2]'

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

Aabc123

BIPv4Address

CName

DID

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Name' or 'ID' instead of 'IPv4Address' will not show the IP address.

The --format option uses Go templates. To get the IP address of container 'abc123', use .Containers.abc123.IPv4Address.

5fill in blank

hard

Fill all three blanks to complete the command that shows the network mode of a container named 'webapp'.

Docker

docker inspect --format='{{{{.[1].[2]' [3]

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

AHostConfig

BNetworkMode

Cwebapp

DConfig

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Config' instead of 'HostConfig' will not find NetworkMode.

Using wrong container name will cause error.

The network mode is found under HostConfig.NetworkMode in the container's inspect data. The container name is 'webapp'.

Practice

1. Which Docker command shows detailed information about a specific network, including connected containers?

easy

A. docker ps

B. docker container inspect <container_id>

C. docker network inspect <network_name>

D. docker network ls

Solution

1. Step 1: Understand the purpose of docker network inspect

   This command provides detailed info about a Docker network, including which containers are connected.

2. Step 2: Compare with other commands

   docker container inspect shows container details, docker ps lists running containers, and docker network ls lists networks without details.

3. Final Answer:

   docker network inspect <network_name> -> Option C

4. Quick Check:

   Network details = docker network inspect [OK]

Hint: Use docker network inspect for network details [OK]

Common Mistakes:

• Confusing container inspect with network inspect
• Using docker ps to get network info
• Using docker network ls for detailed info

2. Which of the following commands correctly shows the IP address of a running container named webapp using docker container inspect with formatting?

easy

A. docker container inspect --format '{{.NetworkSettings.IPAddress}}' webapp

B. docker container inspect --format '{{.Network.IP}}' webapp

C. docker inspect --format '{{.NetworkSettings.IP}}' webapp

D. docker container inspect --format '{{.IPAddress}}' webapp

Solution

1. Step 1: Identify correct JSON path for IP address

   The IP address is under .NetworkSettings.IPAddress in container inspect output.

2. Step 2: Check command syntax

   docker container inspect --format '{{.NetworkSettings.IPAddress}}' webapp uses correct command and format string. Others use incorrect paths or omit 'container'.

3. Final Answer:

   docker container inspect --format '{{.NetworkSettings.IPAddress}}' webapp -> Option A

4. Quick Check:

   IP address path = .NetworkSettings.IPAddress [OK]

Hint: Use .NetworkSettings.IPAddress to get container IP [OK]

Common Mistakes:

• Using wrong JSON path like .Network.IP
• Omitting 'container' in the command
• Using '{{.IPAddress}}' which is invalid

3. Given a container named db connected to a network backend_net, what will the command docker network inspect backend_net show about the container?

medium

A. It lists the container ID and its IPv4 address inside the network.

B. It shows only the container name without IP details.

C. It shows the container's CPU and memory usage.

D. It shows the container's logs.

Solution

1. Step 1: Understand output of docker network inspect

   This command shows network details including connected containers with their IDs and IP addresses.

2. Step 2: Eliminate incorrect options

   It does not show CPU/memory usage or logs, and it includes IP info, not just names.

3. Final Answer:

   It lists the container ID and its IPv4 address inside the network. -> Option A

4. Quick Check:

   Network inspect shows container IDs and IPs [OK]

Hint: Network inspect shows container IDs and IPs connected [OK]

Common Mistakes:

• Expecting resource usage info from network inspect
• Thinking it shows logs
• Assuming only container names appear

4. You run docker container inspect --format '{{.NetworkSettings.IPAddress}}' myapp but get an empty output. What is the most likely reason?

medium

A. The container myapp is not connected to the default bridge network.

B. Docker daemon is not running.

C. The command syntax is incorrect.

D. The container myapp is stopped.

Solution

1. Step 1: Understand when IPAddress is empty

   If a container is stopped, it has no active network interface, so IPAddress is empty.

2. Step 2: Check other options

   Not connected to default network still shows IP if connected elsewhere; syntax is correct; daemon not running causes errors, not empty output.

3. Final Answer:

   The container myapp is stopped. -> Option D

4. Quick Check:

   Stopped container IP is empty [OK]

Hint: Empty IP means container likely stopped [OK]

Common Mistakes:

• Assuming wrong syntax causes empty output
• Thinking network choice causes empty IP
• Ignoring container running state

5. You want to list all containers connected to a custom network mynet and show their names and IP addresses in a simple table. Which approach is best?

hard

A. Run docker ps and guess which containers belong to mynet.

B. Use docker network inspect mynet and parse the JSON to extract container names and IPs.

C. Use docker container inspect --format '{{.Name}} {{.NetworkSettings.IPAddress}}' on all containers and filter manually.

D. Restart Docker daemon to refresh network info.

Solution

1. Step 1: Identify command that shows network container info

   docker network inspect mynet lists all containers connected with their IPs.

2. Step 2: Understand why other options are less effective

   docker ps doesn't show network info; inspecting all containers is manual and error-prone; restarting daemon is unrelated.

3. Final Answer:

   Use docker network inspect mynet and parse the JSON to extract container names and IPs. -> Option B

4. Quick Check:

   Network inspect shows connected containers best [OK]

Hint: Use docker network inspect to get connected containers easily [OK]

Common Mistakes:

• Using docker ps to find network info
• Inspecting containers individually without filtering
• Restarting daemon unnecessarily