[dns-operations] Maximum TTL limits on public resolvers

[Sadiq Saif]

Hi all,

While doing some checks on records in my zones I noticed that two public resolvers limit maximum TTL values. Google Public DNS limits to six hours and Quad9 limits to twelve hours. I tested this with a freshly created A record to forgo the possibility of caching. The actual TTL of the record at the authoritative servers is twenty four hours.

What is the technical or other reason(s) for such TTL limiting?

-- 
  Sadiq Saif
  https://sadiqsaif.com