Allow resolving both IPv4 and IPv6 with --all-nameservers (--no-preference)#604
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…if we're not recycling
This allows dual-stack machines to use A/AAAA records interchangeably during iteration. Validated with --all-nameservers and --iterative. Want to add a table-driven test for all possible values of network options to at least ensure we can return something.
…ipv4-and-ipv6-ns-iterative
…Ses depending on flag
… IP mode. Surface our internal logic of gleaning what mode we should be in
…ebase and use the standard one, a few lints too
…n-demand in the resolver but otherwise this msg is weird to a user with empty local addrs
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zakird
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May 26, 2026
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Description
The concept of "iteration preference" was used when I added
--all-nameservers. We want to discover what nameservers an IP has, and to do so we request theAorAAAArecords for the nameservers. The underlying assumption here was that nameservers are unique by their domain name, and so the IPv4 or IPv6 address of them should be interchangeable.The issue opener wanted to resolve both. To do so, I added a `--all-nameservers-all-ips
Adds a new
--all-nameservers-all-ipsthat:Caveats
no-preference- If a user uses--all-nameserverswithout specifying an iteration preference, by default we'll flip a coin and pick a random one. Of course, if a scanning host only has IPv4 or only IPv6 support, we'll only query for A or AAAA records, respectively.--all-nameservers-all-ipsimplies--all-nameserversOther Improvements
Infologs to help with explainability.And if a user provides a local address:
And if a user provides nameservers
Testing
In
zdns_test.go, I added a very large table-driven test to cover various permutations of options. This helped me discover several bugs in how we handlectx's and timeouts.These skip tests for IP versions the test host doesn't support, ie. on GH runners that lack IPv6, we'll skip any tests with IPv6. For testing we attempt to establish an outbound connection to an IPv4 and IPv6 resolver to test for connectivity before testing.
Happy Path Testing
While the full output is massive, here is a summary of the Cloudflare resolvers queried from a host with IPv6 capability for
dns-testing.com. Note that there's a result for each IP forns-cloud-cN.googledomains.comfor N = 1,2,3,4.Related Issues
Closes #598