Feb 8 – 9, 2024 Workshop
Embassy Suites Charlotte Uptown
US/Eastern timezone

The Impact of Negative Caching and DNS Resolution Failures

Feb 8, 2024, 12:05 PM
Salon A/B (Embassy Suites Charlotte Uptown)

Salon A/B

Embassy Suites Charlotte Uptown

401 East Martin Luther King Jr Blvd Charlotte NC 28202 United States
In-Person Standard Presentation OARC 42 Day 1


Yannis Labrou (Verisign)


Recursive resolvers can aggressively requery Root and TLD authoritative name servers when all authoritative name servers for a zone return REFUSED or SERVAIL. These resolution failures consist of the same query tuple <QNAME, QTYPE, QCLASS> being asked repeatedly at an unexpectedly high rate. The cause of the excessive traffic is almost always related to aggressive resolver retry logic and negative caching behavior. There are numerous conditions that can lead to resolution failures; regardless, this resolver behavior can significantly increase query load to the authoritative name servers.

This presentation will report on a longitudinal analysis of SERVFAIL-related requery traffic to two root name servers and the thirteen com/net authoritative name servers. The analysis will demonstrate that such traffic is consistent, persistent, and sizeable.

Talk duration

Primary author

Yannis Labrou (Verisign)


Matthew Thomas (Verisign)

Presentation materials