[DNSOP] QNAME minimization is bad

[John R Levine <[e-mail]>]

Well, not always bad but sometimes.

A friend of mine who works on DNSBLs wrote yesterday (quite by 
coincidence, unware that there's a meeting this week) asking if anyone has 
thought about this problem: DNSBLs have the same form as rDNS, IPv4 names 
all start with four labels containing digits, IPv6 names start with 
sixteen single character hex digit labels.  In nearly every case the 
entire DNSBL is in a single zone so minimization wastes a lot of queries 
crawling down the zone.  Queries to DNSBLs are fairly randomly distributed 
so 8020 doesn't help much.  If a cache gets to a point where the remaining 
labels look like this, it is almost certainly rDNS or a DNSBL and the 
cache should stop crawling and send the full query.

I'd like to write a draft that updates RFC 9156 by describing situations 
like this that caches could recognize and avoid useless churn, added to 
section 2.3 which already suggests special casing underscored labels.

There are probably others I haven't thought of; who's done research on this?

Regards,
John Levine, [e-mail], Taughannock Networks, Trumansburg NY
Please consider the environment before reading this e-mail. https://jl.ly