Non-Standard Large TTLs in DNS Query Responses
Yuval Shavitt, Omer Shreibstein · 2025
The DNS RFC defines a maximal TTL as MaxInt, namely 231 - 1, which affects the design of systems and repositories for DNS results. We show that there are cases where resolvers answer with larger values, up to 232 - 1, which may translate to negative numbers if the repository is using the standard singed integer representation, or crash a system.