Nov 29 – 30, 2021
UTC timezone
OARC 36 Day 1 - begins 14:00 UTC Today 29 November

Querying the Public Suffix List via the DNS

Nov 30, 2021, 11:40 AM
Standard Presentation Online Workshop OARC 36 Day 2


Peter Thomassen (deSEC)


Information from the Public Suffix List (PSL) is required in various contexts, for example for cookie scoping in browsers, for certificate issuance, and for the secure operation of authoritative multi-tenant nameservers. Applications depending on the PSL customarily bring their own copy of the list, and thus require mechanisms to parse and interpret the list, and to keep it up to date.

The PSL Query Service removes the need for applications to parse or refresh the PSL altogether. Based on a mapping of the PSL onto the DNS, it instead facilitates single-query lookups to immediately retrieve the public suffix that is associated with a given name.

In this short contribution, I discuss the motivation, design, and applications of the PSL Query Service and explain its internal structure, before reflecting on privacy concerns that may arise. The talk ends with considerations about whether and how to better integrate the service into the Internet community.

Primary author

Peter Thomassen (deSEC)

Presentation materials