[theodorton]

Domains that have less frequent lookups so the chance of getting a cached response is lower.

[lloydatkinson]

Why aren't they just called infrequently used domains then?

[jasode]

>Why aren't they just called infrequently used domains then?

You could call them "infrequent" but "long-tail" is also a common description to convey a Power Law distribution: https://en.wikipedia.org/wiki/Long_tail

I think in this case about DNS caching, "long tail" is better than "infrequent". In the wikipedia graph, some of the domain lookups in yellow may be "frequent" (absolute sense) but simultaneously but much less popular (long tail) such that they don't stay in DNS lookup caches.

[lloydatkinson]

DNS is essentially a cache. I've never once in my life heard of infrequently accessed cache items as "long-tail". This is definitely a dumb phrase that should be avoided.

[GauntletWizard]

I've never heard them referred to as anything else, so YMMV

[jasode]

>I've never once in my life heard of infrequently accessed cache items as "long-tail".

The parent poster wrote "long tail _domains_" and not cache items: https://news.ycombinator.com/item?id=29036188

You also used the word "domains" when you asked about "infrequently used domains" and that's the context I was responding to. I didn't say that cache items are labeled "long tail".