DNS-udbredelsestjek
Vi stiller flere offentlige rekursive resolvere det samme spørgsmål og sammenligner svarene.
Dækning: 6 offentlige resolvere, forespurgt fra vores server i Europa. Det er ikke en verdensomspændende måling; den viser, hvad disse resolvere har i cachen lige nu.
Denne tekst findes endnu ikke på dansk. Den vises på engelsk, indtil en oversættelse er udgivet.
“DNS propagation” isn’t really propagation: when you change a record, the authoritative name server has the new value at once, but every recursive resolver keeps its cached copy until that copy’s TTL runs out. Different resolvers cached the record at different moments, so for a while some return the old value and some the new one.
This tool asks the same question to several large public resolvers at the same moment and lists their answers side by side, with the remaining TTL each one reports. When they all agree, the change is visible to most of the internet. Some names deliberately return different answers depending on where the question comes from (CDNs, geo-DNS), so disagreement isn’t always a stale cache.
Ofte stillede spørgsmål
How long does a DNS change take?
At most the old record's TTL, counted from when each resolver last fetched it. Lowering the TTL a day before a planned change shortens the window.
Can I clear a public resolver's cache?
Some operators offer a purge page (Cloudflare and Google do). Otherwise you have to wait for the TTL to expire.