[toast0]

It should, but like the sibling, I haven't seen what Go does. I've seen it happen elsewhere. Exchange used to cache any answer it got until it restarted. Java has had that behavior from time to time if you're not careful as well.

Querying DNS can be expensive, so it makes sense to build a cache to avoid querying again when you don't need to, but typical APIs for name resolution such as gethostbyname / getaddrinfo don't return the TTL, so people just assume forever is a good TTL. Especially for a persistant (http) connection, it kind of makes sense to never query DNS again while you already have a working connection that you made with that name, and if it's TLS, it's quite possible that you don't check if the certificate has expired while you're connected or if you do a session resumption.

But innocent things like this add up to make operating services tricky. Many times, if you start refusing connections, clients figure it out, but sometimes the caches still don't get cleared.

[fotta]

> but typical APIs for name resolution such as gethostbyname / getaddrinfo don't return the TTL

Oh wow I didn’t know this but I looked it up and you’re right. Interesting.

[hypeatei]

I've seen DNS only be refreshed when restarting on embedded devices I work with too. They use a proprietary HTTP library...