Resolver ops

Stub and recursive notes for operators who are exercising the crate, not shipping it as a public resolver.

The overview page still warns that the Client can wait forever. That is not a slogan. On Rust stable the socket options the crate wants are still thin, so a query that never comes back can pin a thread. Treat every lab resolver as a process you can kill.

Stub timeout ledger

Lammas 2026 revisited the UDP idle path so a stub is less likely to sit on a dead nameserver through a whole harvest weekend of tests. The warning on the home page stays. UDP still needs the same honesty: if the peer is silent, fail the query and let the caller retry or walk the next NS.

On 14 Feb 2024 a bench on the TCP client showed a hung read while pulling a modest zone over a lossy loopback pair. The fix was an explicit read deadline on the handoff, not a rewrite of the state machine.

Deep winter 2021 is when the first authority relocation rehearsal proved that a resolver with no deadline will follow a stale NS until someone restarts the process.

UDP first

Use UdpClientConnection for ordinary queries. Watch for TC bits and promote to TCP only when the answer will not fit.

TCP when asked

TcpClientConnection and TcpHandler own the stream. Set a read deadline before you ask for AXFR or a large TXT bundle.

Do not hide errors

The crate goal is that every error is handled. A timeout is an error. Log it, surface it, and do not pretend the nameserver answered.

Crate modules that match this page: client, udp, tcp, and error.