I. Introduction
The Internet’s Domain Name System (DNS) is widely presented as a textbook example of a distributed system with eventual consistency, a system that effectively trades off consistency to improve performance and reduce cost. DNS achieves this design goal through its liberal use of TTL-based caching, a design that also implicitly embeds the synergistic assumption of infrequent updates. Weakly consistent caching alongside hierarchical federation is key to DNS’ scalability.