Oct 3 – 5, 2015
Fairmont Queen Elizabeth
US/Eastern timezone

A study of caching behavior with respect to root server TTLs

Oct 4, 2015, 2:00 PM
St-Francois (Fairmont Queen Elizabeth)


Fairmont Queen Elizabeth

900 René-Lévesque Blvd W Montreal, QC H3B 4A5 Canada


Duane Wessels (Verisign) Matthew Thomas (Verisign)


The Root Server System Advisory Committee (RSSAC) within ICANN was recently tasked with considering the extent to which the current root zone TTLs are appropriate for today's Internet environment and the impacts of root TTL alterations on the wider DNS system. The historical DITL data from 2014 and 2015 was analyzed for trends in TTL adherence, answering some of the following questions: To what degree do root zone TTLs matter? Is there a difference in behavior for authoritative versus non-authoritative data? Do all TLDs exhibit similar inter-query time distributions? Do specific recursive implementations, ISPs, open resolvers, etc. diverge from general TTL adherence trends? How has inter-query time changed over the past two years? Would a change in root zone TTLs result in a change in traffic levels at root name servers?

Primary authors

Duane Wessels (Verisign) Matthew Thomas (Verisign)

Presentation materials