How we saved 100 terabytes of memory by optimizing 1.1.1.1’s DNS cache

Description and use

Optimizing the 1.1.1.1 DNS cache reduced memory usage from 100 TB to 1 TB, improving scalability and cutting costs.

Problem

The 1.1.1.1 DNS cache consumed 100 TB of memory, limiting scalability and increasing operational costs.

Outcome

Reduced memory consumption from 100 TB to 1 TB, enabling higher query throughput and lower infrastructure costs.

Workflow

• 1. Profileed cache memory usage and identified header/payload overhead.
• 2. Designed a new record format with 16‑byte header and 4‑byte payload.
• 3. Implemented the format in the cache codebase and updated serialization logic.
• 4. Deployed changes to a subset of servers and monitored memory usage.
• 5. Rolled out to all 1.1.1.1 servers after confirming stability.

Evidence

We saved 100 terabytes of memory by optimizing 1.1.1.1’s DNS cache

Source