Consul 1.15 Multi Datacenter Federation Practice Test 2 — 15 Questions

Question 1

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 2

Which file path is standard for storing the Consul server configuration, including WAN settings?

Accepted Answer

/etc/consul.d. The '/etc/consul.d' directory is the standard location for Consul configuration files on Linux systems.

Answer

/tmp/consul

Answer

/opt/consul/bin

Answer

/var/lib/consul

Question 3

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 4

Which file format is used for Consul configuration?

Accepted Answer

HCL or JSON. Consul supports both HCL (HashiCorp Configuration Language) and JSON for its configuration files.

Answer

INI

Answer

YAML

Answer

XML

Question 5

What is the benefit of using a Mesh Gateway in a multi-datacenter deployment with overlapping IP space?

Accepted Answer

It allows cross-datacenter traffic without routing overlapping networks.. Mesh gateways allow communication between datacenters with overlapping IP ranges by acting as an SNI-based proxy that terminates and re-originates the mTLS connection.

Answer

It reduces the server memory usage.

Answer

It eliminates the need for ACLs.

Answer

It increases the gossip speed.

Question 6

If you are running Consul Enterprise, what feature simplifies the management of cross-datacenter secrets?

Accepted Answer

ACL Replication.. Consul Enterprise supports cross-datacenter secret replication for specific ACL tokens and KV pairs, often utilized with the 'enterprise_license_path' features.

Answer

KV Mirroring.

Answer

Automatic Secret Rotation.

Answer

Centralized Config.

Question 7

To verify if two datacenters are connected via WAN, which command shows the remote datacenter's server nodes?

Accepted Answer

consul members -wan. The 'consul members -wan' command lists all nodes participating in the WAN gossip pool, regardless of their local datacenter.

Answer

consul members

Answer

consul info

Answer

consul operator raft list-peers

Question 8

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 9

When joining a new datacenter to an existing WAN pool, what is the best practice for server versions?

Accepted Answer

Versions should be consistent across all datacenters.. Running different versions of Consul is supported during upgrades, but maintaining consistent versions across the federation is recommended for stability.

Answer

The new DC must run a newer version.

Answer

The new DC must run an older version.

Answer

Version doesn't matter at all.

Question 10

What is the function of the 'retry_join_wan' configuration?

Accepted Answer

To enable persistent WAN connections.. The 'retry_join_wan' configuration allows the agent to repeatedly attempt to join the WAN gossip pool at startup if the initial attempt fails, improving robustness.

Answer

To sync secondary data.

Answer

To force a specific leader.

Answer

To rotate the encryption key.

Question 11

When using multiple datacenters, what is the primary role of the 'consul-template' tool?

Accepted Answer

To generate configuration files based on Consul data.. Consul-template is often used to watch for changes in the Consul catalog and update application configurations, which can be useful when reflecting cross-DC service information.

Answer

To provision infrastructure.

Answer

To replicate KV stores.

Answer

To manage the Consul cluster nodes.

Question 12

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 13

Which TWO statements are true regarding Consul Mesh Gateways?

Accepted Answer

They are required when direct WAN gossip is not possible between datacenters.. Mesh gateways function at Layer 7 and are essential for connectivity between isolated datacenters.

Answer

They replace the need for Consul servers in the secondary datacenter.

Answer

They increase the latency of LAN gossip.

Answer

They require a separate Consul Enterprise license.

Question 14

Which THREE configuration items are part of a complete WAN gossip setup?

Accepted Answer

The 'server' role flag set to true.. WAN setup requires joining the WAN pool, defining the server role, and potentially setting encryption.

Answer

The 'client_addr' restricted to local only.

Answer

The 'ui' configuration set to true.

Question 15

When configuring an ACL policy for cross-datacenter access, what policy rule is necessary to read service information from a remote datacenter?

Accepted Answer

node_prefix "" { policy = "read" }. You need 'service_prefix' or 'node_prefix' policies that explicitly allow reading in the target datacenter.

Answer

service_prefix "*" { policy = "write" }

Answer

agent_prefix "" { policy = "read" }

Answer

acl_prefix "" { policy = "read" }