FA-7396 / DNS resolution / Open access
Dns additional records do not override authoritative answers · case 01
Dns additional records do not override authoritative answers.
ROOT CAUSE
The faulty implementation uses `dict(answers,**additional)` for the dns-additional-records-do-not-override-authoritative-answers decision.
VERIFIED REPAIR
Apply the explicit dns-additional-records-do-not-override-authoritative-answers contract, including the tested boundary and negative cases.
Unsuccessful approach: The attempted repair uses `dict({k:v for k,v in answers.items() if k in allowed},**additional)` and still violates a separate fixture.
Case contract
Given answers, additional, allowed, dns additional records do not override authoritative answers. Return the protocol decision or transformed value; fields are validated and fixtures state boundary outcomes.
Why this case matters
This deterministic dns resolution model isolates the dns-additional-records-do-not-override-authoritative-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(answers, additional, allowed):
return dict(answers,**additional)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve({'a': 1}, {'a': 2, 'evil': 3}, ['a']), {'a': 1})", "check('fixture 2', solve({}, {'a': 2, 'evil': 3}, ['a']), {'a': 2})", "check('fixture 3', solve({'a': 1}, {}, []), {'a': 1})", "check('fixture 4', solve({}, {}, []), {})"]
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 | {'a': 2, 'evil': 3} | {'a': 2} | Failed |
| fixture 3 | {'a': 1} | {'a': 1} | Passed |
| fixture 4 | {} | {} | Passed |
| fixture 1 | {'a': 2, 'evil': 3} | {'a': 1} | Failed |
SHA-256 / 0e18a464290ab4be03196f2742872454b1a8c18ee5008efbfea1a6d1ea1700d7
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(answers, additional, allowed):
return dict({k:v for k,v in answers.items() if k in allowed},**additional)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve({'a': 1}, {'a': 2, 'evil': 3}, ['a']), {'a': 1})", "check('fixture 2', solve({}, {'a': 2, 'evil': 3}, ['a']), {'a': 2})", "check('fixture 3', solve({'a': 1}, {}, []), {'a': 1})", "check('fixture 4', solve({}, {}, []), {})"]
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 | {'a': 2, 'evil': 3} | {'a': 2} | Failed |
| fixture 3 | {} | {'a': 1} | Failed |
| fixture 4 | {} | {} | Passed |
| fixture 1 | {'a': 2, 'evil': 3} | {'a': 1} | Failed |
SHA-256 / 0c0681eceb0724e5ea5316b3a99b82ffd2ae01d36d3d09c1e3b0a22577553481
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(answers, additional, allowed):
return dict({k:v for k,v in additional.items() if k in allowed}, **answers)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve({'a': 1}, {'a': 2, 'evil': 3}, ['a']), {'a': 1})", "check('fixture 2', solve({}, {'a': 2, 'evil': 3}, ['a']), {'a': 2})", "check('fixture 3', solve({'a': 1}, {}, []), {'a': 1})", "check('fixture 4', solve({}, {}, []), {})"]
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 | {'a': 2} | {'a': 2} | Passed |
| fixture 3 | {'a': 1} | {'a': 1} | Passed |
| fixture 4 | {} | {} | Passed |
| fixture 1 | {'a': 1} | {'a': 1} | Passed |
SHA-256 / ed55ede9c91a1cc494c8f917d41604db8f613c580854c82b338a0d7e16da1152
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 2026-09-29T14:38:11.506573+00:00.
Case digest / 8d526ce032208b04fbbeade0f6e85b6f9049de4bb3a836f907b429245e729e72