Consul 1.15 Practice Test 2 — 25 Questions

Question 1

A service is intermittently failing to resolve via DNS because it has multiple health checks, some of which are 'warning'. How do you ensure it is only returned when all checks are 'passing'?

Accepted Answer

Use the 'passing' query parameter in the DNS request.. Consul DNS returns services if they are not in a 'critical' state by default; enforcing strict 'passing' requires query parameters.

Answer

Configure 'service_prefix' in DNS settings.

Answer

Use the 'stale' query parameter.

Answer

Set 'enable_tag_override' to true.

Question 2

Which THREE network considerations are vital for Consul WAN federation?

Accepted Answer

Sufficient bandwidth for gossip heartbeat messages.. WAN federation requires specific port accessibility, bandwidth for gossip, and routing between servers.

Answer

A shared NAT gateway for all datacenters.

Answer

Uniform MTU settings across all regions.

Question 3

If you need to perform an HTTP check over HTTPS, what configuration option is required to handle self-signed certificates?

Accepted Answer

tls_skip_verify. The 'tls_skip_verify' parameter allows the agent to skip verification of the service's TLS certificate.

Answer

tls_insecure

Answer

disable_tls

Answer

ignore_cert

Question 4

What information does the Consul HTTP API return for a health check? (Select TWO)

Accepted Answer

Output. The API returns the status and the human-readable output of the check.

Answer

Service CPU usage

Answer

Service port

Answer

Check uptime

Question 5

Which of the following are true regarding TTL checks? (Select TWO)

Accepted Answer

They require the app to push updates. TTL checks do not have an interval and require manual updates.

Answer

They are automatically removed

Answer

They are faster than script checks

Answer

They are polled at a fixed interval

Question 6

In a multi-datacenter environment, what happens if the 'primary_datacenter' server cluster becomes unavailable?

Accepted Answer

Secondary datacenters continue to operate, but ACL updates are blocked.. While ACL replication will stall, the secondary datacenters continue to function using their own local raft states.

Answer

Secondary datacenters elect a new primary.

Answer

All secondary datacenters immediately shut down.

Answer

The entire WAN federation is dismantled.

Question 7

When using 'prepared_queries' for cross-datacenter failover, what does the 'failover' block allow you to specify?

Accepted Answer

A list of datacenters to attempt for service resolution.. The 'failover' block in a prepared query allows you to define a list of datacenters to try if the local datacenter lookup returns no healthy instances.

Answer

The timeout for the WAN gossip.

Answer

The encryption algorithm for failover traffic.

Answer

The number of retries per node.

Question 8

Which feature allows you to define a health check that depends on the health of another service?

Accepted Answer

You must implement this logic in a script check. Consul does not support direct service-to-service health check dependencies; instead, you would implement this logic within your application or use a custom script.

Answer

Service dependency field

Answer

Cross-service monitoring

Answer

Service grouping

Question 9

You observe a 'warning' status for a service. What is the most common reason for this?

Accepted Answer

The service is operating but with performance issues. A 'warning' status typically occurs when the service is reachable but is reporting a non-critical issue, such as high latency or exceeding a custom defined threshold in a custom script.

Answer

The agent is restarting

Answer

The network is down

Answer

The service crashed

Question 10

Which of the following conditions can cause a health check to transition to the 'critical' state? (Select TWO)

Accepted Answer

The HTTP check times out. A check transitions to critical if the service fails to respond (timeout) or returns a non-success code (e.g., 500).

Answer

The service is idle

Answer

The service returns a 200 OK

Answer

The disk space is 50% full

Question 11

What is the purpose of the 'Behavior' field when creating a Consul session?

Accepted Answer

To specify what happens to locks on session invalidation.. The behavior field determines what happens to locks when a session is invalidated; 'release' is the default, while 'delete' removes the key.

Answer

To define the node affinity.

Answer

To determine if the session can be renewed.

Answer

To set the session priority.

Question 12

If a KV operation returns a 403 Forbidden status, what is the most common cause?

Accepted Answer

The ACL token lacks sufficient permissions.. ACLs (Access Control Lists) are enabled, and the client token lacks the 'write' permission for that specific prefix.

Answer

The server is down.

Answer

The data is too large.

Answer

The key does not exist.

Question 13

What is the purpose of the 'datacenter' field in the Consul agent configuration?

Accepted Answer

To segment the cluster into logical datacenters.. The datacenter field defines the name of the datacenter the agent belongs to, which is used for service registration and routing.

Answer

To limit the number of clients.

Answer

To enable encryption.

Answer

To identify the node for metrics.

Question 14

You notice that the KV store is not consistent across datacenters. What is the cause?

Accepted Answer

KV store is datacenter-local by design.. Consul does not natively replicate the entire KV store across datacenters by default; it requires separate configuration or manual syncing for state consistency.

Answer

The Raft protocol is broken.

Answer

The ACL token lacks the 'write' permission.

Answer

The WAN gossip is disabled.

Question 15

If a Consul agent is configured with 'disable_remote_exec = true', how does this affect the KV store?

Accepted Answer

It has no effect on the KV store.. This setting does not impact the KV store; it only restricts the execution of remote commands via the Consul event system.

Answer

It forces all KV reads to be consistent.

Answer

It prevents all KV writes.

Answer

It disables KV watches.

Question 16

Which of these are required fields for a TCP health check definition? (Select THREE)

Accepted Answer

name. TCP checks require tcp, interval, and name fields.

Answer

timeout

Answer

http

Question 17

You are configuring a Consul Watch to trigger a script whenever a specific KV key changes. Which type of watch should you define in your configuration file?

Accepted Answer

key. The 'key' watch type is specifically designed to monitor changes to a single KV entry.

Answer

event

Answer

service

Answer

nodes

Question 18

You want to delete a key and all its children in the KV store using the CLI. Which flag should you use?

Accepted Answer

-recurse. The -recurse flag in the CLI allows the delete operation to act on the key and all nested keys.

Answer

-force

Answer

--all

Answer

--cascade

Question 19

You want to perform a blocking query on a KV key to watch for updates. Which parameter must you provide in your request based on the last observed index?

Accepted Answer

index. The index parameter is used in the query string to inform Consul that you want to wait until the current state index is greater than the provided value.

Answer

consistency

Answer

wait

Answer

timeout

Question 20

Which TWO of the following are true about the 'cas' parameter in KV writes?

Accepted Answer

It stands for Check-And-Set. The 'cas' parameter stands for Check-And-Set and requires the index to be provided to ensure atomicity.

Answer

It is only available in the CLI

Answer

It only works for new keys

Answer

It is mandatory for all writes