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FA-7356 / DNS resolution / Open access

Dns rrset ttl uses lowest member ttl · case 01

Dns rrset ttl uses lowest member ttl.

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

ROOT CAUSE

The faulty implementation uses `max(ttls) if ttls else 0` for the dns-rrset-ttl-uses-lowest-member-ttl decision.

VERIFIED REPAIR

Apply the explicit dns-rrset-ttl-uses-lowest-member-ttl contract, including the tested boundary and negative cases.

Unsuccessful approach: The attempted repair uses `sum(ttls)//len(ttls) if ttls else 0` and still violates a separate fixture.

Case contract

Bounded offline decision model: dns rrset ttl uses lowest member ttl. 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-rrset-ttl-uses-lowest-member-ttl 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(ttls):
    return max(ttls) if ttls else 0
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve([30, 60]), 30)", "check('fixture 2', solve([]), 0)", "check('fixture 3', solve([0, 30]), 0)", "check('fixture 4', solve([10]), 10)"]
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 fixtureActualExpectedOutcome
fixture 200Passed
fixture 3300Failed
fixture 41010Passed
fixture 16030Failed

SHA-256 / 5440799591b4e2f5c7800153f379e5afa8baeb6c9b7f6043330dfe0483132a52

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(ttls):
    return sum(ttls)//len(ttls) if ttls else 0
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve([30, 60]), 30)", "check('fixture 2', solve([]), 0)", "check('fixture 3', solve([0, 30]), 0)", "check('fixture 4', solve([10]), 10)"]
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 fixtureActualExpectedOutcome
fixture 200Passed
fixture 3150Failed
fixture 41010Passed
fixture 14530Failed

SHA-256 / 0f847387b455aa442e5c1394623554842900a5a594286c27546278a354b52921

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(ttls):
    return min(ttls) if ttls else 0
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve([30, 60]), 30)", "check('fixture 2', solve([]), 0)", "check('fixture 3', solve([0, 30]), 0)", "check('fixture 4', solve([10]), 10)"]
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 fixtureActualExpectedOutcome
fixture 200Passed
fixture 300Passed
fixture 41010Passed
fixture 13030Passed

SHA-256 / 912f1feab84660e59eddc054d44268cb5ebf4d828b67a10c65638147fd5b26c9

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 2026-09-29T14:38:10.988467+00:00.

Case digest / 49e21741991fc39e4492ee9a98558edb41a26ecc919874eb7fc3fceff20cc2a2