DNS TTL Too High
A TTL (Time to Live) that is set too high means DNS resolvers cache records for extended periods. While high TTLs reduce DNS query load, they dramatically slow down propagation when you need to make changes. If an A record has a TTL of 86400 (24 hours), any change will take up to 24 hours for all resolvers to pick up. This becomes critical during migrations, failovers, or incident response.
Symptoms
- DNS changes take 24–48 hours to propagate
- Failover to a backup server is extremely slow
- Users continue reaching old servers after a migration
- Emergency IP changes do not take effect quickly
Common Causes
- Default TTL left at registrar/provider defaults (often 86400s)
- TTL never reviewed after initial domain setup
- Misunderstanding of TTL impact on change propagation speed
- DNS provider using fixed high TTL with no override option
Step-by-Step Troubleshooting
- 1
- 2
Review SOA record
The SOA record minimum TTL affects negative caching and can override individual record TTLs.
Use SOA Record Lookup → - 3
Plan TTL reduction
Lower TTL to 300–600 seconds at least 48 hours before any planned DNS change.
- 4
Update DNS records
Modify individual record TTLs at your DNS provider to balanced values (300–3600s depending on change frequency).
Use DNS Records Dump → - 5
Verify new TTL is active
Confirm resolvers see the updated TTL by querying from multiple locations.
Use DNS Lookup →
Recommended Diagnostic Tools
Monitor DNS Changes
Track DNS record changes and propagation in real time.