TTL (Time To Live) is the time in seconds during which DNS resolvers (Google 8.8.8.8, Cloudflare 1.1.1.1, ISP) cache the response for your record.
Why TTL:
- Reduces load on our NS servers.
- Speeds up response for users (repeat queries are instant).
- Downside: when you change a record (e.g. server IP), changes are not visible immediately — until the old TTL expires.
Typical TTL values:
- 3600 (1 hour) — standard value.
- 86400 (24 hours) — for records that rarely change.
- 300 (5 minutes) — before migration so changes propagate fast.
What is propagation:
After changing a DNS record (e.g. site IP), the update spreads across the world in 1–24 hours. That is “propagation”. It depends on TTL: the lower the TTL of the old record, the faster everyone sees the new one.
Tip before migration:
1–2 days before changing IP/NS — lower TTL to 300. After migration and verification — set back to 3600.
Check what different DNS resolvers see — third-party tools like dnschecker.org or dig +trace example.tj in terminal.