FA-7341 / DNS resolution / Open access

Dns truncation triggers stream retry even with partial answers · case 01

Dns truncation triggers stream retry even with partial answers.

Verified by executionVariant 1 · 4 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The faulty implementation uses `truncated and not answers` for the dns-truncation-triggers-stream-retry-even-with-partial-answers decision.

VERIFIED REPAIR

Apply the explicit dns-truncation-triggers-stream-retry-even-with-partial-answers contract, including the tested boundary and negative cases.

Unsuccessful approach: The attempted repair uses `not answers` and still violates a separate fixture.

Case contract

Bounded offline decision model: dns truncation triggers stream retry even with partial answers. Inputs are already validated protocol fields; the explicit fixtures define the supported policy, not a complete protocol implementation.

Why this case matters

This deterministic dns resolution model isolates the dns-truncation-triggers-stream-retry-even-with-partial-answers policy at a network component boundary.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import ipaddress
import re
from urllib.parse import urlsplit, urljoin
N = 1
observations = []
def solve(truncated, answers):
    return truncated and not answers
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(True, ['a']), True)", "check('fixture 2', solve(False, []), False)", "check('fixture 3', solve(True, []), True)", "check('fixture 4', solve(False, ['a']), False)"]
for _line in _fixtures[N % len(_fixtures):] + _fixtures[:N % len(_fixtures)]:
    exec(_line)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
fixture 2	`False`	`False`	Passed
fixture 3	`True`	`True`	Passed
fixture 4	`False`	`False`	Passed
fixture 1	`False`	`True`	Failed

SHA-256 / f753ec5089dce83f8862aa9ceafb41bc1bc97dad6fa2617b2cab9341202daa1a

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import ipaddress
import re
from urllib.parse import urlsplit, urljoin
N = 1
observations = []
def solve(truncated, answers):
    return not answers
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(True, ['a']), True)", "check('fixture 2', solve(False, []), False)", "check('fixture 3', solve(True, []), True)", "check('fixture 4', solve(False, ['a']), False)"]
for _line in _fixtures[N % len(_fixtures):] + _fixtures[:N % len(_fixtures)]:
    exec(_line)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
fixture 2	`True`	`False`	Failed
fixture 3	`True`	`True`	Passed
fixture 4	`False`	`False`	Passed
fixture 1	`False`	`True`	Failed

SHA-256 / 5bf8be16a64aa31b8c45312afb5d3e209bf980b437b1dca7c0712d424ef88a55

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import ipaddress
import re
from urllib.parse import urlsplit, urljoin
N = 1
observations = []
def solve(truncated, answers):
    return truncated
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(True, ['a']), True)", "check('fixture 2', solve(False, []), False)", "check('fixture 3', solve(True, []), True)", "check('fixture 4', solve(False, ['a']), False)"]
for _line in _fixtures[N % len(_fixtures):] + _fixtures[:N % len(_fixtures)]:
    exec(_line)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
fixture 2	`False`	`False`	Passed
fixture 3	`True`	`True`	Passed
fixture 4	`False`	`False`	Passed
fixture 1	`True`	`True`	Passed

SHA-256 / d27573d9f7070802c2a7f1ee2a8ab26d34c0bb50d5d5a42bd67294a8ddf01fc8

Verification & scope

Bounded deterministic policy model over validated inputs; not a complete protocol stack or an interoperability claim. The five variants rotate the same explicit fixture set. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:38:10.771211+00:00.

Case digest / f5b47d409590aff2e7f9aa34b4f79b143a2918e3f8caee7d396122bf8bb1a8a6