Prefetch Popular Domains to Improve Cached Response Frequency

[Matt]

@DL6ER

edit See also: https://lists.nlnetlabs.nl/pipermail/unbound-users/2015-February/003793.html
This explanation makes it clear that prefetch ing might not have an effect with caching enabled. It may be a valid point to argue for disabling Pi-hole’s cache. However, mind that DNSSEC will not be available without a cache as the cache is integral to DNSSEC validation. The validation requires the use of a whole set of RRsets. The only way to have all those RRsets is to put them in the cache or you’d generate a ton of requests each time. This would surely be disadvantageous.

Per DL6ER: Caching in Pi-hole inhibits Unbound's prefetching algorithm.

Prefetching in Pi-hole would both support DNSSEC validation (because you wouldn't be disabling the cache) and fix the issue (caching for full TTL duration) that causes prefetching limitations.

Additionally, as proposed, there's more than one way to prefetch, and the first algorithm mentioned is likely favorable in smaller home networks where queries to popular sites aren't as statistically likely to hit during the final 10% of TTL.

Plus, pre-fetching in Pi-hole would benefit everyone, not just those who use Unbound.