dns and language nit

this is a nit about configuring dns. you may not find this interesting unless you’ve had to relate to this too.

so named’s dns soa records contain an “expire” value in seconds, yet a key concern with dns is how long dns records are cached. one might then suspect that the “expire” value had something to do with that no? sadly no! this value has more to do with how secondary servers replicate information. if you want to adjust how long the record is cached typically, you will mostly be interested in the default “ttl” value or “time to live“. this is how long the record should live cached, before it is updated again from the master record holder.

i updated these records on a server i share with many friends, and as you might expect the “expiry” values were all set as if they were time to live values — which must be a common problem, no? the term expire sounds like how long the cached values take to expire. it’s a really unfortunate use of language. sometimes i think a fair portion of user interface design relates to clarity in concept and clarity in language, and the same holds true in programming and programmatic interfaces.