pfSense » pfSense Plus

Description¶

Currently, the CoreDNS implementation/package uses a default TTL (5 minutes / 300 seconds) for served/cached records. For environments requiring rapid failover or dynamic re-routing, this default TTL is too high and leads to extended downtime while clients wait for local DNS cache entries to expire.

Use Case / Motivation¶

In enterprise and dynamic office setups, laptops frequently transition between wired (Ethernet) and wireless (Wi-Fi) connections or dynamic fallback IPs.

With a 5-minute TTL, when a user unplugged their Ethernet cable, their machine retained the cached IP for minutes before querying local DNS again, causing broken connections and delay during network failover.

By allowing a custom low TTL (e.g., 5 seconds), client OS caches expire almost immediately upon physical disconnect, enabling seamless automatic redirection to the secondary network/IP.

Proposed Solution¶

1. Add a configurable TTL / Minimum TTL field in the CoreDNS WebGUI settings page.
2. Allow setting custom integer values in seconds (e.g., range from 0 to 86400).
3. Generate the corresponding `cache` / `template` / plugin directive in the underlying `Corefile` based on this GUI setting.

Expected Result¶

Administrators can fine-tune DNS record lifetime directly from the pfSense UI to match their infrastructure's failover and mobility requirements.