Creating custom bridge networks in Docker - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the command to create a custom bridge network named 'my_bridge'.

Docker

docker network [1] my_bridge

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

Astart

Bbuild

Ccreate

Drun

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'docker network run' instead of 'create'.

Using 'docker network build' which is for images, not networks.

The docker network create command is used to create a new network. Here, it creates a custom bridge network named 'my_bridge'.

2fill in blank

medium

Complete the command to list all Docker networks including the custom bridge networks.

Docker

docker network [1]

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

Aprune

Binspect

Crm

Dls

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'docker network inspect' which shows details of one network only.

Using 'docker network rm' which deletes networks.

The docker network ls command lists all Docker networks, including custom bridge networks.

3fill in blank

hard

Fix the error in the command to create a custom bridge network with a specific subnet.

Docker

docker network create --driver bridge --subnet [1] my_custom_net

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

A192.168.1.0/24

B192.168.1.256/24

C192.168.1.0/33

D192.168.1.0

Attempts:

3 left

💡 Hint

Common Mistakes

Using an IP with 256 in a segment which is invalid.

Using a mask larger than 32 or missing mask.

The subnet must be a valid CIDR block. '192.168.1.0/24' is correct. The others are invalid IP ranges or missing mask.

4fill in blank

hard

Fill both blanks to create a custom bridge network named 'dev_net' with a gateway IP of 172.18.0.1.

Docker

docker network create --driver [1] --subnet 172.18.0.0/16 --gateway [2] dev_net

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

Abridge

Bhost

C172.18.0.1

Doverlay

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'host' or 'overlay' as driver for a bridge network.

Putting driver name as gateway IP.

The driver for a custom bridge network is 'bridge'. The gateway IP must be a valid IP address like '172.18.0.1'.

5fill in blank

hard

Fill all three blanks to create a custom bridge network named 'test_net' with subnet 10.10.0.0/16 and gateway 10.10.0.1.

Docker

docker network create --driver [1] --subnet [2] --gateway [3] test_net

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

Abridge

B10.10.0.0/16

C10.10.0.1

Dhost

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'host' driver instead of 'bridge'.

Using invalid subnet or gateway IP.

Use 'bridge' as the driver for custom bridge networks. The subnet and gateway must be valid IP ranges and addresses.

Practice

1. What is the main purpose of creating a custom bridge network in Docker?

easy

A. To increase the CPU usage of containers

B. To allow containers to communicate privately and securely

C. To automatically update container images

D. To create a backup of container data

Solution

1. Step 1: Understand Docker networking basics

   Docker uses networks to connect containers. The default bridge network is shared and less secure.

2. Step 2: Purpose of custom bridge networks

   Custom bridge networks isolate containers, allowing private and secure communication between them.

3. Final Answer:

   To allow containers to communicate privately and securely -> Option B

4. Quick Check:

   Custom bridge network = private container communication [OK]

Hint: Custom bridge = private container communication [OK]

Common Mistakes:

• Thinking custom bridge increases CPU usage
• Confusing network creation with image updates
• Assuming it creates data backups

2. Which of the following is the correct command to create a custom bridge network named my_bridge?

easy

A. docker network create --driver bridge my_bridge

B. docker create network bridge my_bridge

C. docker network new --type bridge my_bridge

D. docker bridge create network my_bridge

Solution

1. Step 1: Recall Docker network creation syntax

   The correct syntax is docker network create --driver bridge NETWORK_NAME.

2. Step 2: Match the command with the syntax

   docker network create --driver bridge my_bridge matches the correct syntax exactly for creating a bridge network named my_bridge.

3. Final Answer:

   docker network create --driver bridge my_bridge -> Option A

4. Quick Check:

   Correct syntax = docker network create --driver bridge [OK]

Hint: Use 'docker network create --driver bridge NAME' [OK]

Common Mistakes:

• Using wrong command order
• Missing --driver flag
• Using 'new' or 'create' incorrectly

3. Given the command docker network create --driver bridge isolated_net, what will be the output of docker network ls related to this network?

medium

A. No change; the network list remains the same

B. An error message saying 'driver not found' will appear

C. The default bridge network will be removed

D. A new network named 'isolated_net' with driver 'bridge' will appear in the list

Solution

1. Step 1: Understand the effect of the create command

   The command creates a new bridge network named 'isolated_net'.

2. Step 2: Check the network list after creation

   Running docker network ls shows all networks including the newly created 'isolated_net' with driver 'bridge'.

3. Final Answer:

   A new network named 'isolated_net' with driver 'bridge' will appear in the list -> Option D

4. Quick Check:

   New bridge network appears in list [OK]

Hint: New bridge network shows in 'docker network ls' [OK]

Common Mistakes:

• Expecting an error for valid driver
• Thinking default bridge is removed
• Assuming no change in network list

4. You ran docker network create --driver bridge without specifying a network name. What is the likely result?

medium

A. Docker creates a network named 'bridge' by default

B. Docker creates a network with a random generated name

C. Docker throws an error about missing network name

D. Docker creates the default bridge network again

Solution

1. Step 1: Check required arguments for network creation

   The docker network create command requires a network name after options.

2. Step 2: Result of missing network name

   Omitting the network name causes Docker to throw an error indicating the missing argument.

3. Final Answer:

   Docker throws an error about missing network name -> Option C

4. Quick Check:

   Missing name causes error [OK]

Hint: Always specify network name after options [OK]

Common Mistakes:

• Assuming Docker auto-generates network name
• Thinking 'bridge' is default name created
• Confusing with default bridge network

5. You want two containers to communicate only with each other and not with other containers on the host. Which steps correctly create and use a custom bridge network named private_net?

hard

A. Create network with docker network create --driver bridge private_net and run containers with --network private_net

B. Run containers with --link option without creating a network

C. Use default bridge network and assign static IPs manually

D. Create network with docker network create private_net without specifying driver

Solution

1. Step 1: Create a custom bridge network

   Use docker network create --driver bridge private_net to create an isolated network.

2. Step 2: Run containers attached to this network

   Start containers with --network private_net so they communicate only within this network.

3. Final Answer:

   Create network with 'docker network create --driver bridge private_net' and run containers with '--network private_net' -> Option A

4. Quick Check:

   Custom bridge + --network = isolated container communication [OK]

Hint: Create bridge network then run containers with --network [OK]

Common Mistakes:

• Using --link which is deprecated
• Relying on default bridge for isolation
• Omitting --driver option causing default driver