IPv4-Mapped IPv6 Address used in DNS with AAAA-records

[Tore Anderson]

On Fri, 2023-07-28 at 10:04 +0200, Thomas Schäfer wrote:

> "We did this to drive down the cost with our DNS provider. Queries for 
> AAAA records that didn't exist, followed by queries for A records, was 
> costing us significantly and we needed to alleviate that."

Interesting. On my dual-stacked Linux system, this does not reduce the
amount of DNS traffic, as both the A and AAAA queries are issued
simultaneously. Do other platforms behave differently?

Or could it be that their DNS provider's price for a empty (NODATA)
answer is higher than for a regular answer?

If none of the above, I fail to see what they actually gain by doing
this. That said, the approach appears to work well enough as far as I
can tell.

Tore