Container networking in Nginx - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the command to run an nginx container exposing port 80.

Nginx

docker run -d -p [1]:80 nginx

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

A22

B443

C8080

D80

Attempts:

3 left

💡 Hint

Common Mistakes

Using port 443 which is for HTTPS, not HTTP by default.

Using port 22 which is for SSH, unrelated to nginx.

Port 80 is the default HTTP port nginx listens on inside the container. Mapping host port 80 to container port 80 allows access via the host's port 80.

2fill in blank

medium

Complete the docker network command to create a user-defined bridge network named 'webnet'.

Nginx

docker network create [1]

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

Awebnet

Bnone

Chost

Dbridge

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'bridge' which is a driver, not a network name.

Using 'host' or 'none' which are special network modes, not names.

'webnet' is the custom network name to create. The default driver is bridge, so no need to specify it here.

3fill in blank

hard

Fix the error in the command to connect a container named 'web1' to the 'webnet' network.

Nginx

docker network [1] webnet web1

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

Aattach

Blink

Cconnect

Djoin

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'attach' which is for attaching to container's console.

Using 'join' which is not a docker network command.

Using 'link' which is deprecated and limited.

The correct command to add a container to a network is 'docker network connect'.

4fill in blank

hard

Fill both blanks to create a docker network with the bridge driver named 'mynet'.

Nginx

docker network create --driver [1] [2]

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

Abridge

Bhost

Cmynet

Dnone

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'host' or 'none' as driver when bridge is needed.

Using driver name as network name or vice versa.

The bridge driver is the default network driver for user-defined networks. 'mynet' is the chosen network name.

5fill in blank

hard

Fill all three blanks to run an nginx container named 'webapp' connected to 'mynet' network and expose port 8080 on host.

Nginx

docker run -d --name [1] --network [2] -p [3]:80 nginx

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

Awebapp

Bmynet

C8080

Dnginx

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to specify the network.

Mapping wrong ports or missing port mapping.

Using container image name as container name.

The container is named 'webapp', connected to 'mynet' network, and host port 8080 is mapped to container port 80.

Practice

1. What is the main purpose of container networking in Docker?

easy

A. To allow containers to communicate with each other

B. To increase container storage space

C. To speed up container startup time

D. To change container CPU limits

Solution

1. Step 1: Understand container networking basics

   Container networking connects containers so they can share data and services.

2. Step 2: Identify the purpose

   The main goal is to enable communication between containers.

3. Final Answer:

   To allow containers to communicate with each other -> Option A

4. Quick Check:

   Container networking = communication [OK]

Hint: Networking means containers talk to each other [OK]

Common Mistakes:

• Confusing networking with storage or CPU settings
• Thinking networking speeds up container startup
• Assuming networking changes resource limits

2. Which Docker command creates a new custom network for containers?

easy

A. docker create mynet network

B. docker network create mynet

C. docker network new mynet

D. docker create network mynet

Solution

1. Step 1: Recall Docker network creation syntax

   The correct command is docker network create <name>.

2. Step 2: Match the options

   Only docker network create mynet matches the correct syntax exactly.

3. Final Answer:

   docker network create mynet -> Option B

4. Quick Check:

   docker network create = create network [OK]

Hint: Remember: 'docker network create' makes networks [OK]

Common Mistakes:

• Swapping order of 'create' and 'network'
• Using 'new' instead of 'create'
• Adding extra words after network name

3. What will be the result of running this command?

docker run --network mynet nginx

medium

A. The nginx container connects to the 'mynet' network

B. The nginx container creates a new network named 'mynet'

C. The command fails because '--network' is invalid

D. The container runs without any network connection

Solution

1. Step 1: Understand the '--network' flag

   The flag connects the container to an existing network named 'mynet'.

2. Step 2: Analyze the command effect

   The command runs nginx container attached to 'mynet' network.

3. Final Answer:

   The nginx container connects to the 'mynet' network -> Option A

4. Quick Check:

   --network attaches container to network [OK]

Hint: Use --network to join existing networks [OK]

Common Mistakes:

• Thinking it creates a new network
• Believing '--network' is invalid syntax
• Assuming container runs without network

4. You ran docker run --network mynet nginx but got an error: "network mynet not found". What is the likely fix?

medium

A. Restart Docker service and try again

B. Remove the '--network' option from the command

C. Create the network first using docker network create mynet

D. Use docker network connect mynet nginx instead

Solution

1. Step 1: Understand the error message

   The error means the network 'mynet' does not exist yet.

2. Step 2: Fix by creating the network

   Use docker network create mynet to create it before running the container.

3. Final Answer:

   Create the network first using docker network create mynet -> Option C

4. Quick Check:

   Network must exist before use [OK]

Hint: Create network before attaching containers [OK]

Common Mistakes:

• Skipping network creation
• Trying to connect without network existing
• Assuming restart fixes network errors

5. You want two nginx containers to communicate using a custom network. Which steps correctly set this up?

hard

A. Run containers normally, then use docker network connect mynet <container> without creating network

B. Run containers with --link mynet option to connect them

C. Create network with docker create network mynet, then run containers without network option

D. Create network with docker network create mynet, then run both containers with --network mynet

Solution

1. Step 1: Create a custom network

   Use docker network create mynet to make a network for containers.

2. Step 2: Run containers attached to the network

   Start both nginx containers with --network mynet to connect them.

3. Final Answer:

   Create network with docker network create mynet, then run both containers with --network mynet -> Option D

4. Quick Check:

   Create network + attach containers = communication [OK]

Hint: Create network first, then run containers on it [OK]

Common Mistakes:

• Using wrong command to create network
• Not attaching containers to the network
• Using deprecated --link option