FA-7386 / DNS resolution / Open access
Dns alias answer lifetime cannot exceed any chain link · case 01
Dns alias answer lifetime cannot exceed any chain link.
ROOT CAUSE
The faulty implementation uses `target_ttl` for the dns-alias-answer-lifetime-cannot-exceed-any-chain-link decision.
VERIFIED REPAIR
Apply the explicit dns-alias-answer-lifetime-cannot-exceed-any-chain-link contract, including the tested boundary and negative cases.
Unsuccessful approach: The attempted repair uses `max(alias_ttls+[target_ttl])` and still violates a separate fixture.
Case contract
Bounded offline decision model: dns alias answer lifetime cannot exceed any chain link. 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-alias-answer-lifetime-cannot-exceed-any-chain-link 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(alias_ttls, target_ttl):
return target_ttl
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve([10, 30], 60), 10)", "check('fixture 2', solve([], 60), 60)", "check('fixture 3', solve([60], 10), 10)", "check('fixture 4', solve([0], 60), 0)"]
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 | 60 | 60 | Passed |
| fixture 3 | 10 | 10 | Passed |
| fixture 4 | 60 | 0 | Failed |
| fixture 1 | 60 | 10 | Failed |
SHA-256 / 3f2c8f323f02575cf258c3bc3b9e41b93f872b25910562903aed372cecbb1361
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(alias_ttls, target_ttl):
return max(alias_ttls+[target_ttl])
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve([10, 30], 60), 10)", "check('fixture 2', solve([], 60), 60)", "check('fixture 3', solve([60], 10), 10)", "check('fixture 4', solve([0], 60), 0)"]
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 | 60 | 60 | Passed |
| fixture 3 | 60 | 10 | Failed |
| fixture 4 | 60 | 0 | Failed |
| fixture 1 | 60 | 10 | Failed |
SHA-256 / e05532a4f89cdc9b2f7c539da837bf9b4f804bad03ddfbcc8a11a6a6e5fe39bd
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(alias_ttls, target_ttl):
return min(alias_ttls+[target_ttl])
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve([10, 30], 60), 10)", "check('fixture 2', solve([], 60), 60)", "check('fixture 3', solve([60], 10), 10)", "check('fixture 4', solve([0], 60), 0)"]
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 | 60 | 60 | Passed |
| fixture 3 | 10 | 10 | Passed |
| fixture 4 | 0 | 0 | Passed |
| fixture 1 | 10 | 10 | Passed |
SHA-256 / a0f2e0181b038fc4653eafa71d547a58cb18c625a2ca6e25422b4f7cc25736e8
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 2026-09-29T14:38:11.439471+00:00.
Case digest / fe57c1ef245dd9ab2088a659d14ced7f37e334f7a0534e5984eca72d732cc464