On Oct 21, 2016, at 6:35 PM, Eitan Adler <lists@eitanadler.com> wrote:
[...]
In practice TTLs tend to be ignored on the public internet. In past research I've been involved with browser[0] behavior was effectively random despite the TTL set.
[0] more specifically, the chain of DNS resolution and caching down to the browser.
Yes, but that it can be both better and worse than your TTLs does not mean that you can ignore properly working implementations.
If the other end device chain breaks you that's their fault and out of your control. If your own settings break you that's your fault.
+1 to what George wrote that we should make efforts to improve our part of the network. There are ISPs that ignore TTL settings and only update their cached records every two to three days or even more (particularly the smaller ones). OTOH, this results in your DNS data being inconsistent but it’s very common to cache DNS records at multiple levels. It's an effort that everyone needs to contribute to.
Sent from my iPhone