Fun irony (beyond being Friday the 13th): FAA lost radar and frequencies between centers but ADS-B is broadcast by the planes themselves, so a couple hundred hobbyist receivers probably kept the full picture the whole time.
contrary to popular belief, DNS doesn't actually need 24 hours (or whatever) to "propagate". It only needs enough time for caches to expire, if they exist. For non-existent domains this shouldn't be an issue.
DNS controls the length of time an answer is valid (with time-to-live/TTL), some (poorly configured, but for a historical good reason) caching servers ignore the TTL and keep the record much longer (~24 hours).
A non-existent (not yet resolvable) domain, will get an NXDOMAIN response which also gets cached via a TTL setting (which again might be ignored by caching servers).
All that caching - while the current response is still "valid" because the TTL hasn't expired - is what people call "propagation".
Aside from regular caches (that use TTLs), there can also be a replication delay between primary master and secondary master servers.
You make your changes to the zone file on the primary server. The secondary replicates the zone file (a "zone transfer") and uses its copy to serve requests, enabling you to have multiple authoritative servers.
In the old days, the secondary server simply polled the primary server at a fixed interval to see if its zone data was out of date. It could potentially be hours if that's the schedule you chose. It wasn't uncommon to restart the secondary servers by hand if you needed something to propagate faster.
Later, more sophisticated stuff was added like incremental zone transfers and the ability for the primary to send a notification to the secondary instead of relying only on polling. Those made it more practical to replicate quickly.
There were scenarios back in the day when quick replication wasn't worth the cost. The primary and secondary servers might be on opposite sides of a 9600 baud modem connection where zone transfers would eat up a significant portion of available bandwidth.
TLDR: DNS "propagation" is real, not a myth. It's just that today it's pretty trivial to make the propagation delay so tiny that it's negligible.
I remember seeing a similar cool GIF for 9/11 flights, and thought it'd be cool to see if for today's ground stop too, and had Claude Code generate the website in ~30 mins.
Liked it so much and thought I'd clean it up a bit, deploy, and share :) Enjoy!
Very cool. Is this only commercial aircraft? Would be interesting to see if general aviation VFR craft also decreased even though they were technically still allowed to fly as long as it wasn’t from ATC controlled air strips. Though you wouldn’t be able to show it relative to the “expected” number of flights since they aren’t on scheduled flight routes.
It will be fun when the newly (r)elected senators and representatives asks to see the source code. Regulated software needs to have sign offs at each step and proof that procedures were followed.
If they vibe coded this, they will lack the documentation. If they told AI to generate documentation with no human reviews, then they faked it. Anyone who lost money due to flight cancellations should put together a document of losses with proof attached. Have that ready when the lawsuits start. This is the type of corner cutting boeing was doing when it got people killed.
cobychapple | 22 hours ago
monkeymeister | 22 hours ago
gruez | 22 hours ago
contrary to popular belief, DNS doesn't actually need 24 hours (or whatever) to "propagate". It only needs enough time for caches to expire, if they exist. For non-existent domains this shouldn't be an issue.
gnabgib | 22 hours ago
A non-existent (not yet resolvable) domain, will get an NXDOMAIN response which also gets cached via a TTL setting (which again might be ignored by caching servers).
All that caching - while the current response is still "valid" because the TTL hasn't expired - is what people call "propagation".
adrianmonk | 19 hours ago
You make your changes to the zone file on the primary server. The secondary replicates the zone file (a "zone transfer") and uses its copy to serve requests, enabling you to have multiple authoritative servers.
In the old days, the secondary server simply polled the primary server at a fixed interval to see if its zone data was out of date. It could potentially be hours if that's the schedule you chose. It wasn't uncommon to restart the secondary servers by hand if you needed something to propagate faster.
Later, more sophisticated stuff was added like incremental zone transfers and the ability for the primary to send a notification to the secondary instead of relying only on polling. Those made it more practical to replicate quickly.
There were scenarios back in the day when quick replication wasn't worth the cost. The primary and secondary servers might be on opposite sides of a 9600 baud modem connection where zone transfers would eat up a significant portion of available bandwidth.
TLDR: DNS "propagation" is real, not a myth. It's just that today it's pretty trivial to make the propagation delay so tiny that it's negligible.
halamadrid | 22 hours ago
oilkillsbirds | 16 hours ago
throooooo | 15 hours ago
[OP] gvsi | 22 hours ago
Liked it so much and thought I'd clean it up a bit, deploy, and share :) Enjoy!
thirtygeo | 21 hours ago
relyks | 15 hours ago
dheerajvs | 14 hours ago
bmfischer3 | 21 hours ago
[OP] gvsi | 21 hours ago
ChrisArchitect | 20 hours ago
FAA issues national ground stop
https://news.ycombinator.com/item?id=50489641
FAA lifted National Ground Stop at 0119Z
https://news.ycombinator.com/item?id=50492601
joshgermon | 17 hours ago
Something about planes and data visualisation I love, been focus of so many of my random side projects
singhkays | 16 hours ago
krferriter | 17 hours ago
ydna404 | 16 hours ago
bilekas | 15 hours ago
ydna404 | 2 hours ago
Angostura | 14 hours ago
enzoescipy | 11 hours ago
noduerme | 11 hours ago
sevennull | 7 hours ago
roosterIllusi0n | 5 hours ago
If they vibe coded this, they will lack the documentation. If they told AI to generate documentation with no human reviews, then they faked it. Anyone who lost money due to flight cancellations should put together a document of losses with proof attached. Have that ready when the lawsuits start. This is the type of corner cutting boeing was doing when it got people killed.
windexh8er | 5 hours ago
[0] https://github.com/DandelionSprout/adfilt/blob/master/Dandel...