DNS TTL Caching & Zero-Downtime Migration Calculator
Calculate exact zero-downtime DNS migration timelines: pre-cutover TTL step-down lead time, global recursive resolver cache expiration windows, and safe server decommissioning buffers.
DNS Records & Migration Timeline
Existing TTL configured in DNS zone file (e.g. 1 day = 86,400s).
Temporary short TTL used during switchover (e.g. 5 min = 300s).
Minimum cache duration enforced by intermediate resolvers.
sec
RFC 2308 NXDOMAIN cache time (typically 1h = 3,600s).
Migration Timeline
ZERO DOWNTIME SAFE
Pre-Cutover Step-Down Lead Time
48.0 hrs
Lower TTL 2× current TTL before switch
Max Cache Invalidation Window
5.0 mins
Target TTL + resolver cache floor
DNS Authoritative Query Surge
288× QPS
Temporary query load increase
Safe Decommissioning Buffer
24.0 hrs
Keep old server active post-cutover
Recommended 4-Phase Migration Roadmap
1
Step 1: Lower TTL to 300s
Execute at least 48.0 hours prior to planned cutover.
2
Step 2: Switch A / CNAME Records
Point records to new server IP; 99% of clients switch within 5.0 mins.
3
Step 3: Monitor & Fast Rollback Window
Rollback takes max 5.0 mins if issues arise. Keep old host online for 24.0 hrs.
4
Step 4: Restore Original TTL (86400s)
Once stable for 24-48 hours, raise TTL back up to reduce authoritative DNS query load.