TTL Checker

TTL (Time to Live) is a value in seconds attached to a DNS record that tells resolvers how long to cache the record before they must re-query the authoritative nameserver. A TTL of 3600 means the record can be cached for up to one hour. After the TTL expires, the resolver fetches a fresh copy. TTL is set per record — you can have different TTLs for A, MX, and TXT records on the same domain.

For stable records (A records pointing to servers that rarely change), 3600–86400 seconds (1–24 hours) is appropriate. For records you may need to change quickly, use 300–600 seconds (5–10 minutes). Before a planned migration, lower TTL to 300 seconds at least one TTL period in advance, make your change, then restore TTL to normal once propagation is confirmed. Very low TTLs (under 60 seconds) significantly increase query load on your nameservers.

Propagation time is directly tied to the TTL of the record that was changed. If your record had a TTL of 86400 (24 hours) at the time of the change, some resolvers may cache the old value for up to 24 hours before fetching the new one. There is no way to force remote resolvers to flush their cache early. This is why lowering TTL before planned changes is important — it minimises the maximum propagation window.

A TTL of 0 means the record should not be cached at all — every query goes directly to the authoritative nameserver. While technically valid, TTL=0 is rarely practical for production use as it dramatically increases query load. Some DNS providers have minimum TTL floors (e.g. 30 or 60 seconds). TTL=0 is sometimes used for health-check or failover scenarios where near-instant propagation is required, at the cost of significantly higher DNS query volume.