FA-7406 / DNS resolution / Open access

Dns search list is skipped for absolute query name · case 01

Dns search list is skipped for absolute query name.

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

ROOT CAUSE

The faulty implementation uses `[name+"."+s for s in search]+[name]` for the dns-search-list-is-skipped-for-absolute-query-name decision.

VERIFIED REPAIR

Apply the explicit dns-search-list-is-skipped-for-absolute-query-name contract, including the tested boundary and negative cases.

Unsuccessful approach: The attempted repair uses `[name]` and still violates a separate fixture.

Case contract

Bounded offline decision model: dns search list is skipped for absolute query name. 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-search-list-is-skipped-for-absolute-query-name 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(name, search):
    return [name+"."+s for s in search]+[name]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve('host.', ['example']), ['host.'])", "check('fixture 2', solve('host', ['example']), ['host.example', 'host'])", "check('fixture 3', solve('host', []), ['host'])", "check('fixture 4', solve('a.b', ['x', 'y']), ['a.b.x', 'a.b.y', 'a.b'])"]
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	`['host.example', 'host']`	`['host.example', 'host']`	Passed
fixture 3	`['host']`	`['host']`	Passed
fixture 4	`['a.b.x', 'a.b.y', 'a.b']`	`['a.b.x', 'a.b.y', 'a.b']`	Passed
fixture 1	`['host..example', 'host.']`	`['host.']`	Failed

SHA-256 / 87725be34aec6a6a7ccffed3db31fe9466aeb561c79c896f5cdd9fe77aeac053

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(name, search):
    return [name]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve('host.', ['example']), ['host.'])", "check('fixture 2', solve('host', ['example']), ['host.example', 'host'])", "check('fixture 3', solve('host', []), ['host'])", "check('fixture 4', solve('a.b', ['x', 'y']), ['a.b.x', 'a.b.y', 'a.b'])"]
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	`['host']`	`['host.example', 'host']`	Failed
fixture 3	`['host']`	`['host']`	Passed
fixture 4	`['a.b']`	`['a.b.x', 'a.b.y', 'a.b']`	Failed
fixture 1	`['host.']`	`['host.']`	Passed

SHA-256 / 9ea90ca07c6b44dd7fb981f4236897413837cfd9d5fc74648a01e9f840933337

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(name, search):
    return [name] if name.endswith(".") else [name+"."+s for s in search]+[name]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve('host.', ['example']), ['host.'])", "check('fixture 2', solve('host', ['example']), ['host.example', 'host'])", "check('fixture 3', solve('host', []), ['host'])", "check('fixture 4', solve('a.b', ['x', 'y']), ['a.b.x', 'a.b.y', 'a.b'])"]
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	`['host.example', 'host']`	`['host.example', 'host']`	Passed
fixture 3	`['host']`	`['host']`	Passed
fixture 4	`['a.b.x', 'a.b.y', 'a.b']`	`['a.b.x', 'a.b.y', 'a.b']`	Passed
fixture 1	`['host.']`	`['host.']`	Passed

SHA-256 / 148d4e96b2f9340a6bcd05c866113672addae9f034863a05797dc9d875f09c4a

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 2026-09-29T14:38:11.563909+00:00.

Case digest / b8eccc5e42d6e65431ccfa8ef075780f0bcfe82b5f97504ab8e1227c5f841d56