In June of 2014, I gave an invited talk to the Research & Education Track of NANOG 61 explaining what a Discovery Proxy was (Hybrid Proxy at the time) and how Long Lived Queries (LLQ) works. The link at the end of the slides http://hypd.info is no longer valid and should be changed to https://dnsdisco.com.

Here are the slides:

NANOG 61 Slides