Creating a Redundant Pi-hole System

Initial Setup

Deploy Pi-hole on at least two separate devices, which can be Raspberry Pis, virtual machines, or Docker containers. Configure each Pi-hole instance with:

• A unique static IP address
• Identical blocklists and configuration settings (transfer these using Pi-hole's Teleporter feature for backup and restore)

Network Configuration Options

Router-Based Setup

Configure your router's DHCP settings to use both Pi-hole servers:

• Primary DNS: 192.168.1.2
• Secondary DNS: 192.168.1.3

Device-Level Setup

If your router only supports a single DNS server, manually configure devices to use both Pi-hole instances. This can be done on individual computers, phones, and other network devices.

Configuration Synchronization

Maintain identical settings across Pi-hole instances by implementing automatic synchronization:

rsync -avz /etc/pihole/ user@secondary_pihole:/etc/pihole/

Set this up as a scheduled task using cron for regular synchronization.

DHCP Management

When using Pi-hole's DHCP server:

• Enable it on only one instance to prevent conflicts
• If your router supports round-robin DNS, enable it for automatic load distribution between Pi-hole servers

Monitoring

Implement monitoring solutions to track system health:

• Use Pi-hole's built-in dashboard
• Set up advanced monitoring with Grafana or Prometheus
• Monitor uptime using basic tools like ping or services like UptimeRobot

Testing

Regularly test your failover setup by:

• Temporarily disconnecting one Pi-hole instance
• Verifying that DNS resolution continues working
• Checking that ad-blocking remains effective

This redundant setup ensures continuous DNS service and ad-blocking even if one Pi-hole server experiences issues.