Consul 1.15 Practice Exam 2 — 20 Questions

Question 1

What is the default port used for WAN gossip between Consul servers?

Accepted Answer

8302. The default port for WAN gossip is 8302, distinct from the LAN gossip port 8301.

Answer

8301

Answer

8500

Answer

8300

Question 2

Which TWO of the following are prerequisites for successful WAN federation?

Accepted Answer

All datacenters must share the same 'primary_datacenter' setting.. WAN gossip ports must be open between server nodes, and the primary datacenter must be correctly identified.

Answer

All datacenters must have identical node names.

Answer

Consul clients must be able to communicate directly with all remote servers.

Answer

All nodes must be in the same subnet.

Question 3

Which command-line interface command is used to set a value in the Consul KV store?

Accepted Answer

consul kv put. The 'consul kv put' command is the standard CLI utility for setting key values.

Answer

consul kv write

Answer

consul kv set

Answer

consul kv update

Question 4

What happens to a session if the associated node is marked as 'failed' by the Consul health check?

Accepted Answer

The session is invalidated when the TTL expires.. When a node fails, the sessions associated with that node are invalidated after the session TTL expires.

Answer

The session stays active.

Answer

The session is immediately deleted.

Answer

The session is transferred to another node.

Question 5

Which THREE of the following are standard Consul KV CLI subcommands?

Accepted Answer

put. 'put', 'get', and 'delete' are the standard CLI subcommands for KV.

Answer

describe

Answer

list

Question 6

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 7

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 8

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 9

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 10

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 11

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 12

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 13

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 14

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 15

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 16

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 17

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 18

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 19

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 20

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.