#curl DNS in 2026, part II, covers the options in curl for performing DNS lookups and what this means in the context of ECH/HTTPS-RR.

https://eissing.org/icing/posts/curl-dns-options/

curl dns 2026, part II, options

In part I I talked about the changes to DNS resolution in curl and why we do them. In order to see where they apply and if/under which conditions you benefit, we need to shine some light on what “DNS resolution” in curl is. Options As you probably know, curl and libcurl is available on many platforms with capabilities that vary greatly. This also applies to DNS resolution. One configures at build time what mechanism to use. That might require additional libraries like c-ares. Not enough flexibility? You can also at runtime tell curl to use DNS-over-HTTPS (DoH).

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