How It Works
When a server looks up a domain, it keeps the answer for a while instead of asking again on every request. The record's TTL, in seconds, says how long. A TTL of 3600 means one hour; 86400 means a day. Every resolver between the visitor and the domain, the laptop, the home router, the internet provider, keeps its own copy for that long.
gableexterior.example. 300 IN A 170.187.157.144
Why It Matters When Something Changes
Move a website to a new server and update the A record, and anyone whose resolver cached the old answer keeps going to the old server until their copy expires. With a day-long TTL, that is a day of some visitors seeing the old site and some the new. With a five-minute TTL, it is over before anyone notices.
The move is to lower the TTL a day or two before the change, so every cached copy out there expires and is refreshed with the short value, then make the change, then put the TTL back up afterward. The Digital Foundation entry calls this out: low TTLs and centralized management so changes reach the internet with minimal delay.
The Other Direction
Very short TTLs on records that never change mean every lookup is a real query, which is slower for visitors and more load on the DNS server. Records that are stable sit at an hour or more. Records about to move sit at five minutes. The number is a tool, not a setting to forget.
How To Check It
Any DNS lookup tool shows the TTL beside each record. A domain whose records all sit at 86400 has never been tuned, and the next migration will be a slow one.
The Foundation Connection
TTL is part of the clean, deliberately managed DNS the Digital Foundation depends on. It is the small number that decides whether infrastructure changes are invisible to customers or a day of confusion.
