Comment by rini17
7 years ago
That can be acceptable price for minimizing the impact of accidental DNS misconfiguration. Which probably happened to every sysadmin.
Or is there a better way to quickly invalidate DNS caches in case of emergency?
7 years ago
That can be acceptable price for minimizing the impact of accidental DNS misconfiguration. Which probably happened to every sysadmin.
Or is there a better way to quickly invalidate DNS caches in case of emergency?
No, there isn’t. The specification as implemented requires no invalidation mechanism, which means no such mechanism across all caches exists, nor will it ever. The long tail kills you in such a failure scenario, and remember, people who make kitchen appliances write DNS resolvers.
Google Public DNS, at least, provides a public web form you can use to clear cached DNS records [0].
Not sure about any others.
[0]: https://developers.google.com/speed/public-dns/cache
Yeah, this was my first thought...I am guessing the author has never accidentally pushed out a bad DNS entry and needed to revert/update.
Everyone probably starts with higher TTLs, then the first time they mess up an update they switch to a short one.
The author seems to not appreciate how big a problem a misconfigured, long TTL DNS entry could be for someone.
Other reasons for short TTLs... maybe an IP gets blocked/flagged by a large network and they need to change fast... or a network path is slow and they need to move to a new location.