SecondDNS
Documentation

DNS Monitoring

How it works

SecondDNS periodically queries the SOA serial of each zone from both your master DNS server and our secondary NS. If the serials diverge or the master becomes unreachable, the zone is flagged.

Status indicators

Each zone in the dashboard shows two icons — zone status and health check status.

Zone status (Server icon)
ActiveZone is synced and serving DNS records.
PendingZone added, waiting for first AXFR transfer.
ErrorLast sync attempt failed — check master IP and AXFR permissions.
Health check (Activity icon)
SyncedSOA serial matches the master — zone is up to date.
StaleOur serial is behind the master — AXFR may have failed or is delayed.
DownMaster DNS unreachable or our NS cannot be queried.

Check frequency

Default: every 30 minutes. You can override this per zone in Dashboard → Zones → ⚙️ → Check interval. Minimum: 15 minutes.

Email alerts

Disabled by default. Enable globally in Dashboard → Settings → DNS Health Alerts, or per zone via the zone's ⚙️ monitoring settings. When enabled, you'll receive an email when zones become stale or unreachable, and a recovery email when they return to synced.

API access

Query health status programmatically for all zones or a single zone. Supports JSON and Nagios-compatible plain text format. API Reference

# JSON
curl -H "X-API-Key: KEY" https://seconddns.com/api/health/zones

# Nagios format
curl -H "X-API-Key: KEY" "https://seconddns.com/api/health/zones?format=nagios"

Ready-made integrations

Nagios / Icinga

Check plugin with standard exit codes and perfdata.

Zabbix

YAML template with HTTP Agent, JSONPath, and triggers.

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