EX188 Networking And Compose Practice Test 2 — 15 Questions

Question 1

An administrator creates a custom CNI network using 'podman network create mynet' and wants to assign a static IP address to a container upon creation. Which option achieves this?

Accepted Answer

podman run --network mynet --ip 192.168.100.50 -d myimage. The `--ip` flag combined with `--network mynet` is the correct way to assign a static IP to a container on a custom CNI network in Podman. The syntax `podman run --network mynet --ip 192.168.100.50 -d myimage` attaches the container to the named network and requests the specified IP from the network's IPAM range. The IP must fall within the subnet defined when the network was created.

Answer

podman run --network mynet:192.168.100.50 -d myimage

Answer

podman network connect --ip 192.168.100.50 mynet container_id

Answer

podman run --net-static-ip 192.168.100.50 -d myimage

Question 2

You need to configure a container so that its port 8080 maps to port 80 on the host's loopback interface only (127.0.0.1). Which syntax is correct?

Accepted Answer

podman run -p 127.0.0.1:80:8080 myapp. The correct syntax for binding a published container port to a specific host IP is `-p HOST_IP:HOST_PORT:CONTAINER_PORT`. Option D, `-p 127.0.0.1:80:8080`, maps container port 8080 to host port 80, but only on the loopback interface 127.0.0.1, which is exactly what the question requires. This restricts external access so only processes on the host itself can reach the service.

Answer

podman run --net 127.0.0.1:80:8080 myapp

Answer

podman run -p 80:8080/127.0.0.1 myapp

Answer

podman run --publish 8080:80/lo myapp

Question 3

A container needs to be created that shares the host's network stack entirely, bypassing any NAT or virtual interface overhead. Which Podman flag achieves this?

Accepted Answer

--network host. Using --network host disables network isolation and places the container directly on the host's network namespace.

Answer

--share-net

Answer

--publish host

Answer

--net bridge

Question 4

Which Podman network mode completely isolates a container from any network communication, removing all interfaces except the loopback?

Accepted Answer

--network none. The `--network none` option in Podman creates a container with a completely isolated network namespace that contains only the loopback interface (lo). No veth pair, no bridge attachment, and no external connectivity is configured, so the container cannot send or receive any network traffic beyond itself. This is the canonical way to run a container with zero network exposure for security-sensitive workloads.

Answer

--network isolated

Answer

--network closed

Answer

--network disabled

Question 5

You need to inspect the configuration details, including subnet, gateway, and driver, of a custom Podman network named 'appnet'. Which command should you run?

Accepted Answer

podman network inspect appnet. 'podman network inspect <name>' returns detailed JSON configuration for the specified network, including subnet, gateway, driver, IPAM options, and connected containers. This is the correct command to inspect a custom Podman network's configuration details.

Answer

podman inspect --network appnet

Answer

podman network show appnet

Answer

podman network status appnet

Question 6

You want to remove a custom Podman network named 'testnet', but it currently has active containers attached to it. What happens?

Accepted Answer

The deletion fails until all connected containers are stopped and disconnected.. Podman refuses to remove a network that has active containers attached to it; the deletion fails with an error indicating the network is in use. The administrator must first stop and disconnect all containers (or use podman network disconnect) before the network can be removed. This prevents silently breaking container connectivity and orphaned interfaces.

Answer

The network is removed, and the containers lose their network interface silently.

Answer

The containers are automatically disconnected and moved to the default bridge network.

Answer

The containers are automatically terminated and the network is removed.

Question 7

Two containers running on the same custom user-defined bridge network need to communicate using container names as hostnames. What is required for this to work natively in Podman?

Accepted Answer

Nothing extra; user-defined bridge networks include built-in DNS resolution.. User-defined bridge networks in Podman (and Docker) include an embedded DNS resolver, typically at 127.0.0.11 inside each container, that resolves container names and network aliases to their current IP addresses. Because both containers are attached to the same custom network, Podman's DNS plugin (dnsname/aardvark-dns) automatically registers each container's name, so no manual /etc/hosts editing or --link is needed. This is a core advantage of user-defined networks over the default bridge, which lacks automatic name resolution.

Answer

You must use the default 'podman' bridge network.

Answer

You must edit /etc/hosts inside the containers manually.

Answer

You must manually link containers using the --link flag.

Question 8

How do you list all available Podman networks on your system?

Accepted Answer

podman network ls. 'podman network ls' is the correct command to list all Podman networks. The 'ls' subcommand is the standard Podman verb for listing resources, consistent with 'podman volume ls', 'podman image ls', and 'podman container ls'.

Answer

podman network list

Answer

podman network status

Answer

podman network show

Question 9

Which command starts services defined in a Podman Compose file in detached mode?

Accepted Answer

podman-compose up -d. `podman-compose up -d` is the direct equivalent of `docker-compose up -d`: it creates and starts all services defined in the compose file and runs them in detached (background) mode. The `-d` flag is the standard shorthand for `--detach` across both Docker Compose and podman-compose.

Answer

podman-compose background

Answer

podman-compose start --detach

Answer

podman-compose run -d

Question 10

You need to configure a container port mapping in Podman Compose so that host port 80 forwards to container port 8080. Which YAML syntax is correct under the service definition?

Accepted Answer

ports:
  - "80:8080". In Podman Compose (and Docker Compose), the ports key under a service takes a list of strings in the form "HOST:CONTAINER" to publish a container port on the host. So "80:8080" maps host port 80 to container port 8080. The quotes are recommended because YAML can misinterpret bare numbers containing colons.

Answer

publish:
  - 80->8080

Answer

expose:
  - "80:8080"

Answer

ports:
  container: 8080
  host: 80

Question 11

In a Podman Compose file, how do you define a custom network and connect a service to it?

Accepted Answer

Define networks at the root level and reference them under each service configuration.. In a Podman Compose file, custom networks are declared under a top-level networks: block, and each service references the desired network(s) under its own networks: key. This two-part structure is required by the Compose specification: the root-level declaration defines the network (driver, options, external flag), and the service-level reference attaches the service to it. This is how Compose wires services into shared networks for name resolution and isolation.

Answer

Use the 'links:' directive inside the service block exclusively.

Answer

Add a 'network_mode' string directly pointing to an external shell script.

Answer

Configure networking exclusively via command-line environment variables.

Question 12

You wish to connect an already running container to an existing custom Podman network named 'mynet'. Which command should you use?

Accepted Answer

podman network connect mynet mycontainer. 'podman network connect' attaches a running or stopped container to a specified network.

Answer

podman network attach mynet mycontainer

Answer

podman container network-add mynet mycontainer

Answer

podman network join mynet mycontainer

Question 13

Which flag allows you to publish a container port to a random ephemeral port on the host interface?

Accepted Answer

-P. The -P (uppercase) flag tells podman to publish all EXPOSED ports from the image to randomly assigned ephemeral ports on the host. This is the documented shorthand for --publish-all, and it satisfies the requirement of mapping to a random host port without specifying a fixed number. Lowercase -p requires explicit port mappings and does not have a 'random' keyword.

Answer

-p random

Answer

-p 0:8080

Answer

--port dynamic

Question 14

How do you disconnect a running container from a custom network named 'mynet'?

Accepted Answer

podman network disconnect mynet mycontainer. The `podman network disconnect` command removes a container from a specified network, taking the network name and container name as arguments. This is the exact syntax for detaching a running container from a custom network like 'mynet' without stopping it. It is the counterpart to `podman network connect`.

Answer

podman container disconnect mynet mycontainer

Answer

podman network remove mynet mycontainer

Answer

podman network detach mynet mycontainer

Question 15

You need to troubleshoot name resolution between containers on a custom network. Which backend service does Podman utilize by default for container DNS resolution in modern rootless setups?

Accepted Answer

aardvark-dns. In modern rootless Podman setups, container name resolution on user-defined networks is handled by aardvark-dns, a lightweight authoritative DNS server that Podman launches per network. It reads container name/IP mappings from the network's configuration and answers A/AAAA queries from containers, enabling name-based communication without editing /etc/hosts.

Answer

nscd

Answer

dnsmasq

Answer

bind9