Configuring different TTLs in multiple RRs for the same domain name, TYPE, and CLASS

Ray Bellis ray at
Thu Mar 24 16:46:17 UTC 2016

On 24/03/2016 16:41, Tony Finch wrote:

> When I changed our TTLs from 24h to 1h last year, it didn't have a visible
> effect on authoritative server query load, much to my surprise.

I'm not that surprised - there's definitely not a linear correlation
between the TTL of an RRset and how frequently it's queried.

Unless your TTL is very short, forced expulsion from cache (due to
cache-size limits) would cause many clients to re-query for a record far
more frequently than once-per-TTL.


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