DNS resolution between containers in Docker - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the command to create a Docker network named 'mynetwork'.

Docker

docker network create [1]

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

Abridge

Bdefault

Cmynetwork

Dhost

Attempts:

3 left

💡 Hint

Common Mistakes

Using default network names like 'bridge' or 'host' which are predefined.

The command docker network create mynetwork creates a new user-defined network named 'mynetwork'. This network allows containers to communicate by name.

2fill in blank

medium

Complete the command to run a container named 'web' attached to the 'mynetwork' network.

Docker

docker run -d --name web --network [1] nginx

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

Abridge

Bmynetwork

Chost

Dnone

Attempts:

3 left

💡 Hint

Common Mistakes

Using default networks like 'bridge' which may not support container name resolution as expected.

Using --network mynetwork attaches the container to the user-defined network 'mynetwork', enabling DNS resolution between containers on that network.

3fill in blank

hard

Fix the error in the command to ping the 'web' container from another container on the same network.

Docker

docker run --rm --network mynetwork alpine ping -c 3 [1]

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

Aweb

Blocalhost

C127.0.0.1

Dgoogle.com

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'localhost' or '127.0.0.1' which refer to the current container itself.

Using the container name 'web' allows DNS resolution within the 'mynetwork' network, so the ping command reaches the correct container.

4fill in blank

hard

Fill both blanks to create a Docker Compose service named 'db' using the 'mysql' image and connect it to the 'mynetwork' network.

Docker

services:
  db:
    image: mysql
    networks:
      - [1]
networks:
  [2]:

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

Amynetwork

Bdefault

Dbridge

Attempts:

3 left

💡 Hint

Common Mistakes

Using different network names in the two places causing network mismatch.

Both blanks should be 'mynetwork' to define and use the same custom network in Docker Compose, enabling DNS resolution between services.

5fill in blank

hard

Fill all three blanks to define a Docker Compose service 'app' that depends on 'db', uses the 'mynetwork' network, and sets an environment variable 'DB_HOST' to the 'db' service name.

Docker

services:
  app:
    image: myapp
    depends_on:
      - [1]
    environment:
      - DB_HOST=[2]
    networks:
      - [3]

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

Adb

Cmynetwork

Ddefault

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect service names or default networks that break DNS resolution.

The 'app' service depends on 'db', sets the environment variable 'DB_HOST' to 'db' so it can connect by name, and uses the 'mynetwork' network for DNS resolution.