HACKER Q&A
📣 anderspitman

Is there a “wall of shame” for ISPs that don't respect DNS TTLs?


And other DNS resolvers as well.


  👤 tyingq Accepted Answer ✓
Ripe did some testing in 2017 that showed that most places (~94%) are doing the right thing. Somewhere around 6% of the DNS servers were either making the TTL last too long, or too short.

There's a downloadable zip file there where you could probably figure out who the offenders were. Ripe did say that it was a mix of both ISPs and Cloud providers.

https://labs.ripe.net/author/giovane_moura/dns-ttl-violation...

Edit: There are also probably some corporate MITM type "content filtering" caches that are screwing things up too, by caching web pages longer than they should.


👤 Spivak
I think it's a fool's errand into bullying people into solving your operational woes. You pretty much only have one option for dealing with real life DNS.

* Design your system assuming a hostile environment and that propagation time is on the order of hours.

* Draw and document a hard line above which you consider it your user's problem; i.e. you start assuming the world has updated after 2 hours and any stragglers can just get errors.


👤 dsp
What problem are you encountering?

I worked on dns gslb for a long stretch at Facebook^WMeta, and didn’t see an excess of bad actors. The vast majority of users follow our dns changes in an orderly fashion. Most delay sources to clients themselves.


👤 chunkyks
It's shorter to write down a list of good actors.

Generally I just assume a good old fashioned "48 hours", like in the olden days, and I have yet to be disappointed.


👤 pvtmert
yes, any/all Turkish ISPs don't respect the TTL at all...