Cloudflare Reduced DNS Cache Memory Use by 100 Terabytes
A redesign of the 1.1.1.1 DNS cache architecture completed in July 2026 lowered memory usage and latency.
Updated on Sept. 23, 2026 in Data Centers
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Cloudflare successfully reduced its 1.1.1.1 DNS cache memory footprint by 100 terabytes between May 18 and July 6, 2026. The update, which affected a system storing over 250 billion entries, resulted in a 56 percent reduction in memory per entry.
Why it matters
This optimization enables Cloudflare to significantly increase overall cache capacity without expanding physical server hardware. The shift highlights how data structure engineering remains critical for maintaining infrastructure efficiency at scale.
The memory footprint per entry fell from 953 bytes to 420 bytes, while lookup latency decreased by 19 percent. Additionally, cache insertion throughput improved by 43 percent following the transition.
The players
Cloudflare
A global provider of content delivery networks, cybersecurity services, and edge computing infrastructure that operates the 1.1.1.1 public DNS resolver.
The details
Cloudflare achieved these gains by replacing standard language structures like Vec (a growable array) and String with custom Box structures and by packing Booleans into bitflags (a memory-efficient storage method using bits instead of bytes). The team further optimized data handling by storing records in a contiguous byte buffer using the standard DNS wire format, which minimizes allocation overhead. These changes reduced total allocations per entry from 1.1 KB to 461 bytes.
Timeline
The memory optimization rollout began on May 18, 2026.
The rollout concluded on July 6, 2026.
The Tech Race
This performance improvement strengthens Cloudflare's position in the global public DNS market against competitors like Google Public DNS and Quad9. By optimizing the core cache architecture, the company has created a wider margin for capacity scaling compared to previous iterations.
Users of the 1.1.1.1 service may experience slightly faster DNS resolution due to the 19 percent reduction in lookup latency. The freed memory capacity is intended to allow for larger cache sizes, which will likely improve success rates for domain lookups over time.
The takeaway
The successful 100-terabyte reduction demonstrates that micro-optimizations in data structures can yield massive gains at the edge of the internet. Readers should watch for future announcements regarding expanded cache capacity made possible by this freed memory.
Further reading
For more on how infrastructure scale influences performance, browse Data Centers.
Source note: This article includes information reported by InfoQ.
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