DNS64 Calculator
Size a DNS64 resolver: synthesis rate, cache footprint and the share of queries needing AAAA synthesis.
About DNS64 Calculator
DNS64 answers AAAA queries for IPv4-only names by synthesising a record inside the NAT64 prefix. Only the IPv4-only share needs synthesis; the rest is answered natively and can be cached normally. DNS64 sits on the critical path of every connection in an IPv6-only network, so undersizing its cache turns a name lookup into the slowest part of the request.
Formula
DNS64
synthesis rate = queries per second × share of IPv4-only destinations; cache memory = cached names × bytes per entry.
- share
- Proportion of destinations with no AAAA record
- entryBytes
- Average size of a cached record set
Worked example
With the default values below, DNS64 Calculator returns AAAA Records Synthesised of 4,200. Change any input above and every figure here is recalculated in your browser.
Inputs used
- DNS queries per secondaccepts 1–5,000,000 qps
- 12,000 qps
- Destinations that are IPv4-onlyaccepts 0–100 %
- 35 %
- Distinct names cachedaccepts 1–100,000,000 entries
- 400,000 entries
- Bytes per cache entryaccepts 64–4,096 bytes
- 220 bytes
Results
- AAAA Records Synthesised
- 4,200
- Cache Memory
- 84 MiB
- Natively Answered Queries
- 7,800
- Share Requiring Synthesis
- 35.0%
Step by step
- 1Values used
- 2DNS64
- 3AAAA Records Synthesised= 4,200
- 4Cache Memory= 88,000,000
- 5Natively Answered Queries= 7,800
- 6Share Requiring Synthesis= 35.0
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is DNS64 calculated?
synthesis rate = queries per second × share of IPv4-only destinations; cache memory = cached names × bytes per entry. DNS64 answers AAAA queries for IPv4-only names by synthesising a record inside the NAT64 prefix. Only the IPv4-only share needs synthesis; the rest is answered natively and can be cached normally.
Why does DNS64 matter?
DNS64 sits on the critical path of every connection in an IPv6-only network, so undersizing its cache turns a name lookup into the slowest part of the request.
What values do I need to enter?
This calculator takes 4 inputs: DNS queries per second, Destinations that are IPv4-only, Distinct names cached, Bytes per cache entry. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.