Tag: NRPT

Twenty Seconds of Fanout and One NRPT Rule: The True Culprit of the grokbot Hang, Ten Historic DNS Entries on the TAP Adapters, and the Windows Algorithm of Fast Forward and Slow Reverse

The troubleshooting of a permanently hung Grok Bot main window (two minutes of CPU sampled motionless): the first cut cleaned ten historic DNS entries off two disconnected TAP adapters — it did not fix the problem (the PTR reverse lookup still took 20.4 seconds), reported honestly; digging further found the true culprit — the Windows DNS Client fans out reverse queries to every DNS server on every adapter and waits for the slowest, while a forward query returns on the first affirmative answer, which is why only PTR was slow; this machine carries ninja-tun, Tailscale, ZeroTier, Ethernet, two TAP adapters plus loopback/WSL interfaces, and after the fanout the slowest one consumed exactly twenty seconds. The fix is a single NRPT rule pinning the .in-addr.arpa reverse zone to one resolver (223.5.5.5), touching no Ninja config, no system proxy, no routes; after the fix the reverse lookup ran 330-470 milliseconds and the main window read Responding=True. An upgrade notice (0.78.1 is the known hang in the forums, 0.78.5 likely fixes it) waits for the master call.