How To Use DNS-Based Failover Domain

The DNS-Based Failover Domain setting lets FlightVector follow a DNS name that is
managed outside of FlightVector. When that DNS name points to a FlightVector
Server, that server is treated as the active server. Other FlightVector Servers
wait in standby until the DNS name is changed to point to them.

This document is intended for FlightVector administrators and operational users
who need to understand what the setting does and what to expect during failover.

When To Use This Setting

Use DNS-Based Failover Domain when your organization uses an external DNS or load
balancing tool to decide which FlightVector Server should be active.

For example:

• Your primary FlightVector Server is normally active.
• A backup FlightVector Server is available.
• A DNS record, such as flightvector.example.org, is updated by your failover
   process to point to whichever server should be active.
• FlightVector Servers use that DNS record to decide whether they should run as
   the active server or remain on standby.

This setting is typically used instead of Enable Automatic Failover. Do not enable
both unless FlightVector Support has specifically directed you to do so.

What To Enter

In FlightVector, go to:

Administrator -> Settings... -> DNS-Based Failover Domain

Enter the DNS name that should always resolve to the active FlightVector Server.

Example:

flightvector.example.org

Enter only the domain name. Do not include:

• http:// or https://
• A page path, such as /identity
• A trailing slash

After changing the setting, make sure the same value is available to each
FlightVector Server that participates in the DNS-based failover setup.

How It Works

Each FlightVector Server has its own internal server identity. When DNS-Based
Failover Domain is configured, each server checks the configured DNS name and asks
the FlightVector Server currently reached by that name for its identity.

FlightVector then compares the identity returned by the DNS name with the local
server's identity.

If the identities match:

• This server is the active server.
• FlightVector starts normally or continues running normally.
• Users connect to and work through this server.

If the identities do not match:

• This server is not the active server.
• During startup, it waits in standby.
• If it was already running, it restarts and comes back up in standby mode.

This prevents two FlightVector Servers from acting as the active server at the
same time when DNS has selected only one of them.

What Users May See

When the DNS name points to the current server, users should not notice anything
special. FlightVector operates normally.

When a server is waiting in standby, FlightVector may show a message similar to:

This FlightVector Server is standing by, waiting as a failover server until
<domain name> resolves to it.

This means the server is healthy enough to run, but FlightVector is intentionally
waiting because DNS currently identifies another server as active.

During a planned or emergency failover, users may briefly lose connection while
the DNS change takes effect and the newly selected server becomes active. Users
should reconnect using the normal FlightVector address after the failover is
complete.

Basic Failover Process

1. A typical DNS-based failover process looks like this:
2. Confirm that the backup FlightVector Server is running and configured with the same DNS-Based Failover Domain value.
3. Update the external DNS record so the configured domain name points to the backup FlightVector Server.
4. Wait for DNS to resolve to the backup server.
5. The backup server detects that the DNS name now points to itself and becomes active.
6. The previous active server detects that DNS points somewhere else, restarts,
   and waits in standby.

The exact timing depends on your DNS provider, DNS time-to-live settings, network
caching, and the process your organization uses to update DNS.

Turning The Feature Off

To stop using DNS-based failover, clear the DNS-Based Failover Domain setting:

Administrator -> Settings... -> DNS-Based Failover Domain

Leave the value blank and save the setting.

When the setting is blank, FlightVector does not use this DNS-based startup and
standby behavior.

Troubleshooting

The server is stuck waiting in standby:

• Confirm that the DNS-Based Failover Domain value is correct.
• Confirm that the DNS record points to the server that should be active.
• Confirm that DNS changes have had enough time to propagate.
• Confirm that the active FlightVector Server can be reached from the standby server.

No server becomes active:

• Confirm that the DNS record points to a running FlightVector Server.
• Confirm that the configured DNS name does not include a protocol, path, or
   trailing slash.
• Confirm that the external DNS or load balancing tool completed its update.

Users cannot connect after failover:

• Confirm that the DNS name users connect to now resolves to the intended active server.
• Confirm that the active server is running and reachable on the network.
• Ask users to reconnect after the DNS change has completed.

If a server is incorrectly waiting because of a DNS or configuration problem,
contact FlightVector Support before making emergency configuration changes.

Key Points To Remember

• DNS-Based Failover Domain tells FlightVector which server DNS has selected as active.
• The value should be a domain name only.
• The DNS record is managed outside of FlightVector.
• Standby behavior is expected when DNS points to another FlightVector Server.
• This setting is typically used instead of Enable Automatic Failover.
• Clearing the setting disables DNS-based failover behavior.