3 ms·
isn't it usually the opposite, except for client applications that ignore the ttl they got from their recursive resolver as they don't want to bother with keepi
by zhfliz 4y ago
isn't it usually the opposite, except for client applications that ignore the ttl they got from their recursive resolver as they don't want to bother with keeping track of ttls?
- icedchai 4y agoWhen I ran a small web hosting provider, we had some clients (mostly bots, I think) hitting old IPs for months. We had kept the TTL below 5 minutes for a very long time before migration. Also, older Java apps would cache DNS lookups forever, until you restarted the JVM. I remember arguing back and forth in email with a "vendor." They finally believed me and restarted their app server.
- zhfliz 4y agothat's what i meant. the resolvers (which those apps talk to) are (afaik) generally rfc-conforming and respect ttl, though they may have lower max ttl values, allowing faster refreshes in some cases. certain bad applications however just don't bother dealing with ttls at all and assume dns is static and never changes.
- paranoidrobot 4y ago> Also, older Java apps would cache DNS lookups forever, until you restarted the JVM. I remember arguing back and forth in email with a "vendor." They finally believed me and restarted their app server. New JVM-based apps do the same thing. I've had the same conversations with a "partner".
- icedchai 4y agoI figured, after all these years, the JVM would switch to a sane default for DNS caching. Sadly that is not the case...